期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1998
卷号：95
期号：17
页码：9861-9866
DOI：10.1073/pnas.95.17.9861
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Fragments encompassing the apical domain of GroEL, called minichaperones, facilitate the refolding of several proteins in vitro without requiring GroES, ATP, or the cage-like structure of multimeric GroEL. We have identified the smallest minichaperone that is active in vitro in chaperoning the refolding of rhodanese and cyclophilin A: GroEL(193-335). This finding raises the question of whether the minichaperones are active under more stringent conditions in vivo. The smallest minichaperones complement two temperature-sensitive Escherichia coli groEL alleles, EL44 and EL673, at 43{degrees}C. Although they cannot replace GroEL in cells in which the chromosomal groEL gene has been deleted by P1 transduction, GroEL(193-335) enhances the colony-forming ability of such cells when limiting amounts of GroEL are expressed from a tightly regulated plasmid. Surprisingly, we found that overexpression of GroEL prevents plaque formation by bacteriophage {lambda} and inhibits replication of the {lambda} origin-dependent plasmid, Lorist6. The minichaperones also inhibit Lorist6 replication, but less markedly. The complex quaternary structure of GroEL, its central cavity, and the structural allosteric changes that take place on the binding of nucleotides and GroES are not essential for all of its functions in vivo.
