RRC ID 4969
Author Kumar CM, Khare G, Srikanth CV, Tyagi AK, Sardesai AA, Mande SC.
Title Facilitated oligomerization of mycobacterial GroEL: evidence for phosphorylation-mediated oligomerization.
Journal J Bacteriol
Abstract The distinctive feature of the GroES-GroEL chaperonin system in mediating protein folding lies in its ability to exist in a tetradecameric state, form a central cavity, and encapsulate the substrate via the GroES lid. However, recombinant GroELs of Mycobacterium tuberculosis are unable to act as effective molecular chaperones when expressed in Escherichia coli. We demonstrate here that the inability of M. tuberculosis GroEL1 to act as a functional chaperone in E. coli can be alleviated by facilitated oligomerization. The results of directed evolution involving random DNA shuffling of the genes encoding M. tuberculosis GroEL homologues followed by selection for functional entities suggested that the loss of chaperoning ability of the recombinant mycobacterial GroEL1 and GroEL2 in E. coli might be due to their inability to form canonical tetradecamers. This was confirmed by the results of domain-swapping experiments that generated M. tuberculosis-E. coli chimeras bearing mutually exchanged equatorial domains, which revealed that E. coli GroEL loses its chaperonin activity due to alteration of its oligomerization capabilities and vice versa for M. tuberculosis GroEL1. Furthermore, studying the oligomerization status of native GroEL1 from cell lysates of M. tuberculosis revealed that it exists in multiple oligomeric forms, including single-ring and double-ring variants. Immunochemical and mass spectrometric studies of the native M. tuberculosis GroEL1 revealed that the tetradecameric form is phosphorylated on serine-393, while the heptameric form is not, indicating that the switch between the single- and double-ring variants is mediated by phosphorylation.
Volume 191(21)
Pages 6525-38
Published 2009-11-1
DOI 10.1128/JB.00652-09
PII JB.00652-09
PMID 19717599
PMC PMC2795288
MeSH Alleles Amino Acid Sequence Chaperonin 60 / genetics Chaperonin 60 / metabolism* Escherichia coli / metabolism Gene Expression Regulation, Bacterial / physiology Genetic Complementation Test Models, Molecular Molecular Chaperones Mycobacterium tuberculosis / genetics Mycobacterium tuberculosis / metabolism* Phosphorylation
IF 3.234
Times Cited 30
Prokaryotes E. coli ME8998(B178) ME7986(MG1655) CV-25(DH5alpha)