A dynamics based analysis of allosteric modulation in heat shock proteins
- Authors: Penkler, David Lawrence
- Date: 2019
- Subjects: Heat shock proteins , Molecular chaperones , Allosteric regulation , Homeostasis , Protein kinases , Transcription factors , Adenosine triphosphatase , Cancer -- Chemotherapy , Molecular dynamics , High throughput screening (Drug development)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115948 , vital:34273
- Description: The 70 kDa and 90 kDa heat shock proteins (Hsp70 and Hsp90) are molecular chaperones that play central roles in maintaining cellular homeostasis in all organisms of life with the exception of archaea. In addition to their general chaperone function in protein quality control, Hsp70 and Hsp90 cooperate in the regulation and activity of some 200 known natively folded protein clients which include protein kinases, transcription factors and receptors, many of which are implicated as key regulators of essential signal transduction pathways. Both chaperones are considered to be large multi-domain proteins that rely on ATPase activity and co-chaperone interactions to regulate their conformational cycles for peptide binding and release. The unique positioning of Hsp90 at the crossroads of several fundamental cellular pathways coupled with its known association with diverse oncogenic peptide clients has brought the molecular chaperone under increasing interest as a potential anti-cancer target that is crucially implicated with all eight hallmarks of the disease. Current orthosteric drug discovery efforts aimed at the inhibition of the ATPase domain of Hsp90 have been limited due to high levels of associated toxicity. In an effort to circumnavigate this, the combined focus of research efforts is shifting toward alternative approaches such as interference with co-chaperone binding and the allosteric inhibition/activation of the molecular chaperone. The overriding aim of this thesis was to demonstrate how the computational technique of Perturbation response scanning (PRS) coupled with all-atom molecular dynamics simulations (MD) and dynamic residue interaction network (DRN) analysis can be used as a viable strategy to efficiently scan and accurately identify allosteric control element capable of modulating the functional dynamics of a protein. In pursuit of this goal, this thesis also contributes to the current understanding of the nucleotide dependent allosteric mechanisms at play in cellular functionality of both Hsp70 and Hsp90. All-atom MD simulations of E. coli DnaK provided evidence of nucleotide driven modulation of conformational dynamics in both the catalytically active and inactive states. PRS analysis employed on these trajectories demonstrated sensitivity toward bound nucleotide and peptide substrate, and provided evidence of a putative allosterically active intermediate state between the ATPase active and inactive conformational states. Simultaneous binding of ATP and peptide substrate was found to allosterically prime the chaperone for interstate conversion regardless of the transition direction. Detailed analysis of these allosterically primed states revealed select residue sites capable of selecting a coordinate shift towards the opposite conformational state. In an effort to validate these results, the predicted allosteric hot spot sites were cross-validated with known experimental works and found to overlap with functional sites implicated in allosteric signal propagation and ATPase activation in Hsp70. This study presented for the first time, the application of PRS as a suitable diagnostic tool for the elucidation and quantification of the allosteric potential of select residues to effect functionally relevant global conformational rearrangements. The PRS methodology described in this study was packaged within the Python programming environment in the MD-TASK software suite for command-line ease of use and made freely available. Homology modelling techniques were used to address the lack of experimental structural data for the human cytosolic isoform of Hsp90 and for the first time provided accurate full-length structural models of human Hsp90α in fully-closed and partially-open conformations. Long-range all-atom MD simulations of these structures revealed nucleotide driven modulation of conformational dynamics in Hsp90. Subsequent DRN and PRS analysis of these MD trajectories allowed for the quantification and elucidation of nucleotide driven allosteric modulation in the molecular chaperone. A detailed PRS analysis revealed allosteric inter-domain coupling between the extreme terminals of the chaperone in response to external force perturbations at either domain. Furthermore PRS also identified several individual residue sites that are capable of selecting conformational rearrangements towards functionally relevant states which may be considered to be putative allosteric target sites for future drug discovery efforts Molecular docking techniques were employed to investigate the modulation of conformational dynamics of human Hsp90α in response to ligand binding interactions at two identified allosteric sites at the C-terminal. High throughput screening of a small library of natural compounds indigenous to South Africa revealed three hit compounds at these sites: Cephalostatin 17, 20(29)-Lupene-3β isoferulate and 3'-Bromorubrolide F. All-atom MD simulations on these protein-ligand complexes coupled with DRN analysis and several advanced trajectory based analysis techniques provided evidence of selective allosteric modulation of Hsp90α conformational dynamics in response to the identity and location of the bound ligands. Ligands bound at the four-helix bundle presented as putative allosteric inhibitors of Hsp90α, driving conformational dynamics in favour of dimer opening and possibly dimer separation. Meanwhile, ligand interactions at an adjacent sub-pocket located near the interface between the middle and C-terminal domains demonstrated allosteric activation of the chaperone, modulating conformational dynamics in favour of the fully-closed catalytically active conformational state. Taken together, the data presented in this thesis contributes to the understanding of allosteric modulation of conformational dynamics in Hsp70 and Hsp90, and provides a suitable platform for future biochemical and drug discovery studies. Furthermore, the molecular docking and computational identification of allosteric compounds with suitable binding affinity for allosteric sites at the CTD of human Hsp90α provide for the first time “proof-of-principle” for the use of PRS in conjunction with MD simulations and DRN analysis as a suitable method for the rapid identification of allosteric sites in proteins that can be probed by small molecule interaction. The data presented in this section could pave the way for future allosteric drug discovery studies for the treatment of Hsp90 associated pathologies.
- Full Text:
- Date Issued: 2019
- Authors: Penkler, David Lawrence
- Date: 2019
- Subjects: Heat shock proteins , Molecular chaperones , Allosteric regulation , Homeostasis , Protein kinases , Transcription factors , Adenosine triphosphatase , Cancer -- Chemotherapy , Molecular dynamics , High throughput screening (Drug development)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115948 , vital:34273
- Description: The 70 kDa and 90 kDa heat shock proteins (Hsp70 and Hsp90) are molecular chaperones that play central roles in maintaining cellular homeostasis in all organisms of life with the exception of archaea. In addition to their general chaperone function in protein quality control, Hsp70 and Hsp90 cooperate in the regulation and activity of some 200 known natively folded protein clients which include protein kinases, transcription factors and receptors, many of which are implicated as key regulators of essential signal transduction pathways. Both chaperones are considered to be large multi-domain proteins that rely on ATPase activity and co-chaperone interactions to regulate their conformational cycles for peptide binding and release. The unique positioning of Hsp90 at the crossroads of several fundamental cellular pathways coupled with its known association with diverse oncogenic peptide clients has brought the molecular chaperone under increasing interest as a potential anti-cancer target that is crucially implicated with all eight hallmarks of the disease. Current orthosteric drug discovery efforts aimed at the inhibition of the ATPase domain of Hsp90 have been limited due to high levels of associated toxicity. In an effort to circumnavigate this, the combined focus of research efforts is shifting toward alternative approaches such as interference with co-chaperone binding and the allosteric inhibition/activation of the molecular chaperone. The overriding aim of this thesis was to demonstrate how the computational technique of Perturbation response scanning (PRS) coupled with all-atom molecular dynamics simulations (MD) and dynamic residue interaction network (DRN) analysis can be used as a viable strategy to efficiently scan and accurately identify allosteric control element capable of modulating the functional dynamics of a protein. In pursuit of this goal, this thesis also contributes to the current understanding of the nucleotide dependent allosteric mechanisms at play in cellular functionality of both Hsp70 and Hsp90. All-atom MD simulations of E. coli DnaK provided evidence of nucleotide driven modulation of conformational dynamics in both the catalytically active and inactive states. PRS analysis employed on these trajectories demonstrated sensitivity toward bound nucleotide and peptide substrate, and provided evidence of a putative allosterically active intermediate state between the ATPase active and inactive conformational states. Simultaneous binding of ATP and peptide substrate was found to allosterically prime the chaperone for interstate conversion regardless of the transition direction. Detailed analysis of these allosterically primed states revealed select residue sites capable of selecting a coordinate shift towards the opposite conformational state. In an effort to validate these results, the predicted allosteric hot spot sites were cross-validated with known experimental works and found to overlap with functional sites implicated in allosteric signal propagation and ATPase activation in Hsp70. This study presented for the first time, the application of PRS as a suitable diagnostic tool for the elucidation and quantification of the allosteric potential of select residues to effect functionally relevant global conformational rearrangements. The PRS methodology described in this study was packaged within the Python programming environment in the MD-TASK software suite for command-line ease of use and made freely available. Homology modelling techniques were used to address the lack of experimental structural data for the human cytosolic isoform of Hsp90 and for the first time provided accurate full-length structural models of human Hsp90α in fully-closed and partially-open conformations. Long-range all-atom MD simulations of these structures revealed nucleotide driven modulation of conformational dynamics in Hsp90. Subsequent DRN and PRS analysis of these MD trajectories allowed for the quantification and elucidation of nucleotide driven allosteric modulation in the molecular chaperone. A detailed PRS analysis revealed allosteric inter-domain coupling between the extreme terminals of the chaperone in response to external force perturbations at either domain. Furthermore PRS also identified several individual residue sites that are capable of selecting conformational rearrangements towards functionally relevant states which may be considered to be putative allosteric target sites for future drug discovery efforts Molecular docking techniques were employed to investigate the modulation of conformational dynamics of human Hsp90α in response to ligand binding interactions at two identified allosteric sites at the C-terminal. High throughput screening of a small library of natural compounds indigenous to South Africa revealed three hit compounds at these sites: Cephalostatin 17, 20(29)-Lupene-3β isoferulate and 3'-Bromorubrolide F. All-atom MD simulations on these protein-ligand complexes coupled with DRN analysis and several advanced trajectory based analysis techniques provided evidence of selective allosteric modulation of Hsp90α conformational dynamics in response to the identity and location of the bound ligands. Ligands bound at the four-helix bundle presented as putative allosteric inhibitors of Hsp90α, driving conformational dynamics in favour of dimer opening and possibly dimer separation. Meanwhile, ligand interactions at an adjacent sub-pocket located near the interface between the middle and C-terminal domains demonstrated allosteric activation of the chaperone, modulating conformational dynamics in favour of the fully-closed catalytically active conformational state. Taken together, the data presented in this thesis contributes to the understanding of allosteric modulation of conformational dynamics in Hsp70 and Hsp90, and provides a suitable platform for future biochemical and drug discovery studies. Furthermore, the molecular docking and computational identification of allosteric compounds with suitable binding affinity for allosteric sites at the CTD of human Hsp90α provide for the first time “proof-of-principle” for the use of PRS in conjunction with MD simulations and DRN analysis as a suitable method for the rapid identification of allosteric sites in proteins that can be probed by small molecule interaction. The data presented in this section could pave the way for future allosteric drug discovery studies for the treatment of Hsp90 associated pathologies.
- Full Text:
- Date Issued: 2019
Characterization of the Hsp40 partner proteins of Plasmodium falciparum Hsp70
- Authors: Njunge, James Mwangi
- Date: 2014
- Subjects: Plasmodium falciparum , Heat shock proteins , Malaria -- Chemotherapy , Protein-protein interactions , Erythrocytes -- Biotechnology , Molecular chaperones , Host-parasite relationships , Mitochondria
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4117 , http://hdl.handle.net/10962/d1013186
- Description: Human malaria is an economically important disease caused by single-celled parasites of the Plasmodium genus whose biology displays great evolutionary adaptation to both its mammalian host and transmitting vectors. This thesis details the 70 kDa heat shock protein (Hsp70) and J protein chaperone complements in malaria parasites affecting humans, primates and rodents. Heat shock proteins comprise a family of evolutionary conserved and structurally related proteins that play a crucial role in maintaining the structural integrity of proteins during normal and stress conditions. They are considered future therapeutic targets in various cellular systems including Plasmodium falciparum. J proteins (Hsp40) canonically partner with Hsp70s during protein synthesis and folding, trafficking or targeting of proteins for degradation. However, in P. falciparum, these classes of proteins have also been implicated in aiding the active transport of parasite proteins to the erythrocyte cytosol following erythrocyte entry by the parasite. This host-parasite “cross-talk” results in tremendous modifications of the infected erythrocyte, imparting properties that allow it to adhere to the endothelium, preventing splenic clearance. The genome of P. falciparum encodes six Hsp70 homologues and a large number of J proteins that localize to the various intracellular compartments or are exported to the infected erythrocyte cytosol. Understanding the Hsp70-J protein interactions and/or partnerships is an essential step for drug target validation and illumination of parasite biology. A review of these chaperone complements across the Plasmodium species shows that P. falciparum possesses an expanded Hsp70-J protein complement compared to the rodent and primate infecting species. It further highlights how unique the P. falciparum chaperone complement is compared to the other Plasmodium species included in the analysis. In silico analysis showed that the genome of P. falciparum encodes approximately 49 J proteins, 19 of which contain a PEXEL motif that has been implicated in routing proteins to the infected erythrocyte. Most of these PEXEL containing J proteins are unique with no homologues in the human system and are considered as attractive drug targets. Very few of the predicted J proteins in P. falciparum have been experimentally characterized. To this end, cell biological and biochemical approaches were employed to characterize PFB0595w and PFD0462w (Pfj1) J proteins. The uniqueness of Pfj1 and the controversy in literature regarding its localization formed the basis for the experimental work. This is the first study showing that Pfj1 localizes to the mitochondrion in the intraerythrocytic stage of development of P. falciparum and has further proposed PfHsp70-3 as a potential Hsp70 partner. Indeed, attempts to heterologously express and purify Pfj1 for its characterization are described. It is also the first study that details the successful expression and purification of PfHsp70-3. Further, research findings have described for the first time the expression and localization of PFB0595w in the intraerythrocytic stages of P. falciparum development. Based on the cytosolic localization of both PFB0595w and PfHsp70-1, a chaperone – cochaperone partnership was proposed that formed the basis for the in vitro experiments. PFB0595w was shown for the first time to stimulate the ATPase activity of PfHsp70-1 pointing to a functional interaction. Preliminary surface plasmon spectroscopy analysis has revealed a potential interaction between PFB0595w and PfHsp70-1 but highlights the need for further related experiments to support the findings. Gel filtration analysis showed that PFB0595w exists as a dimer thereby confirming in silico predictions. Based on these observations, we conclude that PFB0595w may regulate the chaperone activity of PfHsp70-1 in the cytosol while Pfj1 may play a co-chaperoning role for PfHsp70-3 in the mitochondrion. Overall, this data is expected to increase the knowledge of the Hsp70-J protein partnerships in the erythrocytic stage of P. falciparum development, thereby enhancing the understanding of parasite biology.
- Full Text:
- Date Issued: 2014
- Authors: Njunge, James Mwangi
- Date: 2014
- Subjects: Plasmodium falciparum , Heat shock proteins , Malaria -- Chemotherapy , Protein-protein interactions , Erythrocytes -- Biotechnology , Molecular chaperones , Host-parasite relationships , Mitochondria
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4117 , http://hdl.handle.net/10962/d1013186
- Description: Human malaria is an economically important disease caused by single-celled parasites of the Plasmodium genus whose biology displays great evolutionary adaptation to both its mammalian host and transmitting vectors. This thesis details the 70 kDa heat shock protein (Hsp70) and J protein chaperone complements in malaria parasites affecting humans, primates and rodents. Heat shock proteins comprise a family of evolutionary conserved and structurally related proteins that play a crucial role in maintaining the structural integrity of proteins during normal and stress conditions. They are considered future therapeutic targets in various cellular systems including Plasmodium falciparum. J proteins (Hsp40) canonically partner with Hsp70s during protein synthesis and folding, trafficking or targeting of proteins for degradation. However, in P. falciparum, these classes of proteins have also been implicated in aiding the active transport of parasite proteins to the erythrocyte cytosol following erythrocyte entry by the parasite. This host-parasite “cross-talk” results in tremendous modifications of the infected erythrocyte, imparting properties that allow it to adhere to the endothelium, preventing splenic clearance. The genome of P. falciparum encodes six Hsp70 homologues and a large number of J proteins that localize to the various intracellular compartments or are exported to the infected erythrocyte cytosol. Understanding the Hsp70-J protein interactions and/or partnerships is an essential step for drug target validation and illumination of parasite biology. A review of these chaperone complements across the Plasmodium species shows that P. falciparum possesses an expanded Hsp70-J protein complement compared to the rodent and primate infecting species. It further highlights how unique the P. falciparum chaperone complement is compared to the other Plasmodium species included in the analysis. In silico analysis showed that the genome of P. falciparum encodes approximately 49 J proteins, 19 of which contain a PEXEL motif that has been implicated in routing proteins to the infected erythrocyte. Most of these PEXEL containing J proteins are unique with no homologues in the human system and are considered as attractive drug targets. Very few of the predicted J proteins in P. falciparum have been experimentally characterized. To this end, cell biological and biochemical approaches were employed to characterize PFB0595w and PFD0462w (Pfj1) J proteins. The uniqueness of Pfj1 and the controversy in literature regarding its localization formed the basis for the experimental work. This is the first study showing that Pfj1 localizes to the mitochondrion in the intraerythrocytic stage of development of P. falciparum and has further proposed PfHsp70-3 as a potential Hsp70 partner. Indeed, attempts to heterologously express and purify Pfj1 for its characterization are described. It is also the first study that details the successful expression and purification of PfHsp70-3. Further, research findings have described for the first time the expression and localization of PFB0595w in the intraerythrocytic stages of P. falciparum development. Based on the cytosolic localization of both PFB0595w and PfHsp70-1, a chaperone – cochaperone partnership was proposed that formed the basis for the in vitro experiments. PFB0595w was shown for the first time to stimulate the ATPase activity of PfHsp70-1 pointing to a functional interaction. Preliminary surface plasmon spectroscopy analysis has revealed a potential interaction between PFB0595w and PfHsp70-1 but highlights the need for further related experiments to support the findings. Gel filtration analysis showed that PFB0595w exists as a dimer thereby confirming in silico predictions. Based on these observations, we conclude that PFB0595w may regulate the chaperone activity of PfHsp70-1 in the cytosol while Pfj1 may play a co-chaperoning role for PfHsp70-3 in the mitochondrion. Overall, this data is expected to increase the knowledge of the Hsp70-J protein partnerships in the erythrocytic stage of P. falciparum development, thereby enhancing the understanding of parasite biology.
- Full Text:
- Date Issued: 2014
The characterisation of trypanosomal type 1 DnaJ-like proteins
- Authors: Ludewig, Michael Hans
- Date: 2010
- Subjects: Molecular genetics , Molecular chaperones , Protozoa , Heat shock proteins , Trypanosoma
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4126 , http://hdl.handle.net/10962/d1015205
- Description: Trypanosomes are protozoans, of which many are parasitic, and possess complex lifecycles which alternate between mammalian and arthropod hosts. As is the case with most organisms, molecular chaperones and heat shock proteins are encoded within the genomes of these protozoans. These proteins are an integral part of maintaining the structural integrity of proteins during normal and stress conditions. Heat shock protein 40 (Hsp40) is a co-chaperone of heat shock protein 70 (Hsp70) and in some cases can act as a chaperone. These proteins work together to bind non-native polypeptide structures to prevent unfolded protein aggregrate formation in times of stress, translocate proteins across organelle membranes, and transport unsalvageable proteins to proteolytic degradation by the cellular proteasome. Hsp40s are divided into four types based on their domain structure. Analysis of the nuclear genomes of eight trypanosomatid species revealed that less than 10 of the approximate 70 Hsp40 sequences per genome were Type 1 Hsp40s, many of which contained putative orthologues in the other seven trypanosomatid genomes. One of these Type 1 Hsp40s from T b. brucei, Trypanosoma brucei DnaJ 2 (Tbj2), was functionally characterised in T brucei brucei. RNA interference knockdown of expression in T brucei brucei showed that cells deficient in Tbj2 displayed a severe inhibition of the growth of the cell population. The levels of the Tbj2 protein population in T brucei brucei cells increases after exposure to 42°c and the protein was found to have a generalized cytoplasmic subcellular localization at 37°c. These findings provide evidence that Tbj2 is an orthologue of Yeast DnaJ 1 (Y dj l), an essential S. cerevisiae protein. Hsp40s interact with their partner Hsp70s through their J-domain. The amino acids of the J-domain important for a functional interaction with Hsp70 were examined in Trypanosoma cruzi DnaJ 2 (Tcj2) (the orthologue of Tbj2) and T cruzi DnaJ protein 3 (Tcj3) by testing their ability to substitute for Y dj l in Saccharomyces cerevisae and for DnaJ in Escherichia coli. In both systems, the positively charged amino acids of Helix II and III of the J-domain disrupted the functional interaction of these Hsp40s with their partner Hsp70s. Substitutions in Helix I and IV of the J-domains of Tcj2 and Tcj3 produced varied results in the two different systems, possibly suggesting that these helices serve to define with which Hsp70s a given Hsp40 can interact. The inability of an Hsp40 and an Hsp70 to interact functionally does not necessarily mean a total absence of physical interaction between these proteins. The amino acid substitution of the histidine in the HPD motif (H34Q) of the J-domain of Tcj2 and Tcj3 removed the ability of these proteins to interact functionally with S. cerevisiae Hsp70 (Ssal) in vivo. However, preliminary binding studies using the quartz crystal microbalance with dissipation monitoring (QCM-D) show that Tcj2 and Tcj2(H34Q) both physically interact with M sativa Hsp70 in vitro. This study is the first report to provide evidence that certain trypanosoma! Type 1 Hsp40s are essential proteins. Futhermore, the interaction of these Hsp40s with Hsp70 identified important features of the functional interface of this chaperone machinery.
- Full Text:
- Date Issued: 2010
- Authors: Ludewig, Michael Hans
- Date: 2010
- Subjects: Molecular genetics , Molecular chaperones , Protozoa , Heat shock proteins , Trypanosoma
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4126 , http://hdl.handle.net/10962/d1015205
- Description: Trypanosomes are protozoans, of which many are parasitic, and possess complex lifecycles which alternate between mammalian and arthropod hosts. As is the case with most organisms, molecular chaperones and heat shock proteins are encoded within the genomes of these protozoans. These proteins are an integral part of maintaining the structural integrity of proteins during normal and stress conditions. Heat shock protein 40 (Hsp40) is a co-chaperone of heat shock protein 70 (Hsp70) and in some cases can act as a chaperone. These proteins work together to bind non-native polypeptide structures to prevent unfolded protein aggregrate formation in times of stress, translocate proteins across organelle membranes, and transport unsalvageable proteins to proteolytic degradation by the cellular proteasome. Hsp40s are divided into four types based on their domain structure. Analysis of the nuclear genomes of eight trypanosomatid species revealed that less than 10 of the approximate 70 Hsp40 sequences per genome were Type 1 Hsp40s, many of which contained putative orthologues in the other seven trypanosomatid genomes. One of these Type 1 Hsp40s from T b. brucei, Trypanosoma brucei DnaJ 2 (Tbj2), was functionally characterised in T brucei brucei. RNA interference knockdown of expression in T brucei brucei showed that cells deficient in Tbj2 displayed a severe inhibition of the growth of the cell population. The levels of the Tbj2 protein population in T brucei brucei cells increases after exposure to 42°c and the protein was found to have a generalized cytoplasmic subcellular localization at 37°c. These findings provide evidence that Tbj2 is an orthologue of Yeast DnaJ 1 (Y dj l), an essential S. cerevisiae protein. Hsp40s interact with their partner Hsp70s through their J-domain. The amino acids of the J-domain important for a functional interaction with Hsp70 were examined in Trypanosoma cruzi DnaJ 2 (Tcj2) (the orthologue of Tbj2) and T cruzi DnaJ protein 3 (Tcj3) by testing their ability to substitute for Y dj l in Saccharomyces cerevisae and for DnaJ in Escherichia coli. In both systems, the positively charged amino acids of Helix II and III of the J-domain disrupted the functional interaction of these Hsp40s with their partner Hsp70s. Substitutions in Helix I and IV of the J-domains of Tcj2 and Tcj3 produced varied results in the two different systems, possibly suggesting that these helices serve to define with which Hsp70s a given Hsp40 can interact. The inability of an Hsp40 and an Hsp70 to interact functionally does not necessarily mean a total absence of physical interaction between these proteins. The amino acid substitution of the histidine in the HPD motif (H34Q) of the J-domain of Tcj2 and Tcj3 removed the ability of these proteins to interact functionally with S. cerevisiae Hsp70 (Ssal) in vivo. However, preliminary binding studies using the quartz crystal microbalance with dissipation monitoring (QCM-D) show that Tcj2 and Tcj2(H34Q) both physically interact with M sativa Hsp70 in vitro. This study is the first report to provide evidence that certain trypanosoma! Type 1 Hsp40s are essential proteins. Futhermore, the interaction of these Hsp40s with Hsp70 identified important features of the functional interface of this chaperone machinery.
- Full Text:
- Date Issued: 2010
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