Eukaryotic type II chaperonin CCT interacts with actin through specific subunits
- 1 December 1999
- journal article
- Published by Springer Nature in Nature
- Vol. 402 (6762) , 693-696
- https://doi.org/10.1038/45294
Abstract
Chaperonins assist the folding of other proteins. Type II chaperonins, such as chaperonin containing TCP-1(CCT), are found in archaea and in the eukaryotic cytosol. They are hexadecameric or nonadecameric oligomers composed of one to eight different polypeptides. Whereas type I chaperonins like GroEL are promiscuous, assisting in the folding of many other proteins, only a small number of proteins, mainly actin and tubulin, have been described as natural substrates of CCT. This specificity may be related to the divergence of the eight CCT subunits. Here we have obtained a three-dimensional reconstruction of the complex between CCT and alpha-actin by cryo-electron microscopy and image processing. This shows that alpha-actin interacts with the apical domains of either of two CCT subunits. Immunolabelling of CCT-substrate complexes with antibodies against two specific CCT subunits showed that actin binds to CCT using two specific and distinct interactions: the small domain of actin binds to CCTdelta and the large domain to CCTbeta or CCTepsilon (both in position 1,4 with respect to delta). These results indicate that the binding of actin to CCT is both subunit-specific and geometry-dependent. Thus, the substrate recognition mechanism of eukaryotic CCT may differ from that of prokaryotic GroEL.Keywords
This publication has 17 references indexed in Scilit:
- 3D reconstruction of the ATP-bound form of CCT reveals the asymmetric folding conformation of a type II chaperonin.Nature Structural & Molecular Biology, 1999
- The Cytosolic Class II Chaperonin CCT Recognizes Delineated Hydrophobic Sequences in Its Target ProteinsBiochemistry, 1999
- Crystal Structure of the Thermosome, the Archaeal Chaperonin and Homolog of CCTPublished by Elsevier ,1998
- The Hsp70 and Hsp60 Chaperone MachinesCell, 1998
- Structure of the Substrate Binding Domain of the Thermosome, an Archaeal Group II ChaperoninCell, 1997
- The Chaperonin Containing t-complex polypeptide 1 (TCP-1). Multisubunit Machinery Assisting in Protein Folding and Assembly in the Eukaryotic CytosolEuropean Journal of Biochemistry, 1995
- The crystal structure of the bacterial chaperonln GroEL at 2.8 ÅNature, 1994
- A yeast TCP-1-like protein is required for actin function in vivo.Proceedings of the National Academy of Sciences, 1994
- Facilitated folding of actins and tubulins occurs via a nucleotide-dependent interaction between cytoplasmic chaperonin and distinctive folding intermediates.Molecular and Cellular Biology, 1994
- Atomic structure of the actin: DNase I complexNature, 1990