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Identification and kinetic analysis of a functional homolog of elongation factor 3, YEF3 in Saccharomyces cerevisiae
Author(s) -
Sarthy Aparna V.,
Mcgonigal Tom,
Capobianco John O.,
Schmidt Michael,
Green Simon R.,
Moehle Charles M.,
Goldman Robert C.
Publication year - 1998
Publication title -
yeast
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.923
H-Index - 102
eISSN - 1097-0061
pISSN - 0749-503X
DOI - 10.1002/(sici)1097-0061(199802)14:3<239::aid-yea219>3.0.co;2-b
Subject(s) - biology , enzyme kinetics , elongation factor , saccharomyces cerevisiae , ribosomal protein , gene , ribosome , yeast , atpase , ef tu , ribosomal rna , biochemistry , microbiology and biotechnology , recombinant dna , enzyme , rna , active site
Yeast and other fungi contain a soluble elongation factor 3 (EF‐3) which is required for growth and protein synthesis. EF‐3 contains two ABC cassettes, and binds and hydrolyses ATP. We identified a homolog of the YEF3 gene in the Saccharomyces cerevisiae genome database. This gene, designated YEF3B , is 84% identical in protein sequence to YEF3 , which we will now refer to as YEF3A . YEF3B is not expressed during growth under laboratory conditions, and thus cannot rescue growth of YEF3A deletion strains. However, YEF3B can take the place of YEF3A in vivo when expressed from the YEF3A or ADH1 promoters. The products of the YEF3A and YEF3B genes, EF‐3A and EF‐3B, respectively, were expressed from the ADH1 promoter and purified. Both factors possessed basal and ribosomal‐stimulated ATPase activity, and had similar affinity for yeast ribosomes (103 to 113 nm). K m values for ATP were similar, but the K cat values differed significantly. Ribosome‐dependent ATPase activity of EF‐3A was more efficient than EF‐3B, since the K cat and K cat / K m values for EF‐3A were about two‐fold higher; however, the difference in K cat / K m values between the two factors was small for basal ATPase activity. © 1998 John Wiley & Sons, Ltd.