Molecular and Cellular Biology, August 1999, p. 5257-5266, Vol. 19, No. 8
0270-7306/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
, a Guanine
Nucleotide Exchange Factor, Enhance Translational Fidelity
Department of Molecular Genetics and
Microbiology,
Received 8 December 1998/Returned for modification 22 January
1999/Accepted 18 May 1999
Translation elongation factor 1
(EF-1
) is a member of the
family of guanine nucleotide exchange factors, proteins whose activities are important for the regulation of G proteins critical to
many cellular processes. EF-1
is a highly conserved protein that
catalyzes the exchange of bound GDP for GTP on EF-1
, a required step
to ensure continued protein synthesis. In this work, we demonstrate that the highly conserved C-terminal region of Saccharomyces
cerevisiae EF-1
is sufficient for normal cell growth. This
region of yeast and metazoan EF-1
and the metazoan EF-1
-like
protein EF-1
is highly conserved. Human EF-1
, but not human
EF-1
, is functional in place of yeast EF-1
, even though both
EF-1
and EF-1
have previously been shown to have guanine
nucleotide exchange activity in vitro. Based on the sequence and
functional homology, mutagenesis of two C-terminal residues identical
in all EF-1
protein sequences was performed, resulting in mutants
with growth defects and sensitivity to translation inhibitors. These
mutants also enhance translational fidelity at nonsense codons, which
correlates with a reduction in total protein synthesis. These results
indicate the critical function of EF-1
in regulating EF-1
activity, cell growth, translation rates, and translational fidelity.
*
Corresponding author. Mailing address: Department of
Molecular Genetics and Microbiology, UMDNJ Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854-5635. Phone: (732) 235-5450. Fax: (732) 235-5223. E-mail: kinzytg{at}umdnj.edu.
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