Open AccessYdj1 Protects Nascent Protein Kinases from Degradation and Controls the Rate of Their Maturation
Author(s) -
Animesh Mandal,
Nadinath B. Nillegoda,
Jennifer A. Chen,
Avrom J. Caplan
Publication year - 2008
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.00543-08
Subject(s) - cdc37 , biology , chaperone (clinical) , kinase , geldanamycin , mutant , hsp90 , microbiology and biotechnology , saccharomyces cerevisiae , biochemistry , hsp70 , co chaperone , protein kinase a , heat shock protein , gene , medicine , extracellular signal regulated kinases , pathology
Ydj1 is aSaccharomyces cerevisiae Hsp40 molecular chaperone that functions with Hsp70 to promote polypeptide folding. We identified Ydj1 as being important for maintaining steady-state levels of protein kinases after screening several chaperones and cochaperones in gene deletion mutant strains. Pulse-chase analyses revealed that a portion of Tpk2 kinase was degraded shortly after synthesis in aydj1 Δ mutant, while the remainder was capable of maturing but with reduced kinetics compared to the wild type. Cdc28 maturation was also delayed in theydj1 Δ mutant strain. Ydj1 protects nascent kinases in different contexts, such as when Hsp90 is inhibited with geldanamycin or whenCDC37 is mutated. The protective function of Ydj1 is due partly to its intrinsic chaperone function, but this is minor compared to the protective effect resulting from its interaction with Hsp70.SIS1 , a type II Hsp40, was unable to suppress defects in kinase accumulation in theydj1 Δ mutant, suggesting some specificity in Ydj1 chaperone action. However, analysis of chimeric proteins that contained the chaperone modules of Ydj1 or Sis1 indicated that Ydj1 promotes kinase accumulation independently of its client-binding specificity. Our results suggest that Ydj1 can both protect nascent chains against degradation and control the rate of kinase maturation.