Eukaryotic chaperonin containing T-complex polypeptide 1 interacts with filamentous actin and reduces the initial rate of actin polymerization in vitro.
We have previously observed that subunits of the chaperonin required for actin production (type-II chaperonin containing T-complex polypeptide 1 [CCT]) localize at sites of microfilament assembly. In this article we extend this observation by showing that substantially substoichiometric CCT reduces the initial rate of pyrene-labeled actin polymerization in vitro where eubacterial chaperonin GroEL had no such effect. CCT subunits bound selectively to F-actin in cosedimentation assays, and CCT reduced elongation rates from both purified actin filament "seeds" and the short and stabilized, minus-end blocked filaments in erythrocyte membrane cytoskeletons. These observations suggest CCT might remain involved in biogenesis of the actin cytoskeleton, by acting at filament (+) ends, beyond its already well-established role in producing new actin monomers.
Grantham
Julie
J
Department of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK.
Ruddock
Lloyd W
LW
Roobol
Anne
A
Carden
Martin J
MJ
D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D000818:Animals; D056404:Chaperonin Containing TCP-1; D018833:Chaperonins / Q000378:metabolism*; D005057:Eukaryotic Cells / Q000378:metabolism; D066298:In Vitro Techniques; D011108:Polymers / Q000378:metabolism; D011817:Rabbits; D051381:Rats
D000199:Actins; D011108:Polymers; D056404:Chaperonin Containing TCP-1; D018833:Chaperonins