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GTP-yeast actin
Journal article   Open access   Peer reviewed

GTP-yeast actin

Kuo-Kuang Wen, Xiaoyi Yao and Peter A Rubenstein
The Journal of biological chemistry, Vol.277(43), pp.41101-41109
10/25/2002
DOI: 10.1074/jbc.M204025200
PMID: 12191996
url
https://doi.org/10.1074/jbc.M204025200View
Published (Version of record) Open Access

Abstract

Because of the apparently greater conformational flexibility of yeast versus muscle actin and the ability of other members in the actin protein superfamily to efficiently use both ATP and GTP, we assessed the ability of yeast actin to function with GTP. Etheno-ATP exchange studies showed that the binding of GTP to yeast actin is about 1/9 as tight as that of ATP in contrast to the 1/1,240 ratio for muscle actin. Proteolysis of GTP-bound G-yeast actin suggests that the conformation of subdomain 2 is very much like that of ATP-bound actin, but CD studies show that GTP-bound actin is less thermostable than ATP-bound actin. GTP-actin polymerizes with an apparent critical concentration of 1.5 microm, higher than that of ATP-actin (0.3 microm) although filament structures observed by electron microscopy were similar. Yeast actin hydrolyzes GTP in a polymerization-dependent manner, and GTP-bound F-actin decorates with the myosin S1. Conversion of Phe(306) in the nucleotide binding site to the Tyr found in muscle actin raised the nucleotide discrimination ratio from the 1/9 of wild-type actin to 1/125. This result agrees with modeling that predicts that removal of the Tyr hydroxyl will create a space for the C2 amino group of the GTP guanine.
 Saccharomyces cerevisiae - metabolism Adenosine Triphosphate - metabolism Base Sequence Cations, Divalent - metabolism Electrophoresis, Polyacrylamide Gel Actins - metabolism Actins - chemistry Models, Molecular Protein Binding Guanosine Triphosphate - metabolism DNA Primers

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