Characterization of Plasmodium falciparum co-chaperone p23: its intrinsic chaperone activity and interaction with Hsp90.
It is well known that the co-chaperone p23 regulates Hsp90 chaperone activity in protein folding. In Plasmodium falciparum, a putative p23 (Pfp23) has been identified through genome analysis, but its authenticity has remained unconfirmed since co-immunoprecipitation experiments failed to show its interaction with P. falciparum Hsp90 (PfHsp90). Thus, recombinant Pfp23 and PfHsp90 proteins purified from expressed clones were used in this study. It was clear that Pfp23 exhibited chaperone activity by virtue of its ability to suppress citrate synthase aggregation at 45 degrees C. Pfp23 was also shown to interact with PfHsp90 and to suppress its ATPase activity. Analyses of modeled Pfp23-PfHsp90 protein complex and site-directed mutagenesis further revealed strategically placed amino acid residues, K91, H93, W94 and K96, in Pfp23 to be crucial for binding PfHsp90. Collectively, this study has provided experimental evidence for the inherent chaperone function of Pfp23 and its interaction with PfHsp90, a sequel widely required for client protein activation.
Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, 5 Science Drive 2, Singapore, 117597, Singapore.
Chun-Song
CS
Chua
Huiyu
H
Low
Kian-Sim
KS
Goo
T S
TS
Sim
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000596:Amino Acids; D000818:Animals; D003001:Cloning, Molecular; D019295:Computational Biology; D004591:Electrophoresis, Polyacrylamide Gel; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D015636:Magnesium Chloride / Q000494:pharmacology; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000378:metabolism*; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000378:metabolism; D010963:Plasmodium falciparum / Q000187:drug effects / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D015800:Protozoan Proteins / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D020449:Repetitive Sequences, Amino Acid; D017384:Sequence Deletion; D013329:Structure-Activity Relationship
D000596:Amino Acids; D018841:HSP90 Heat-Shock Proteins; D018832:Molecular Chaperones; D050505:Mutant Proteins; D015800:Protozoan Proteins; D011994:Recombinant Proteins; D015636:Magnesium Chloride; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases