Interaction between elongation factors 1β and 1γ from bombyx mori silk gland

Abstract

Elongation factor 1 (EF-1) from the silk gland of Bombyx mori consists of four subunits: α (51 kDa), β (26 kDa), γ (49 kDa), and δ (33 kDa). The EF-1α subunit catalyzes the binding of aminoacyl-tRNA to the ribosome concomitant with the hydrolysis of GTP. The EF-1α-bound GDP is then exchanged for GTP by the EF-1βγδ complex. To facilitate analysis of the roles of the individual EF-1β, γ, and δ subunits in GDP/GTP exchange on EF-1α, we cloned the cDNAs for these subunits and expressed them in Escherichia coli. EF-1β, EF-1γ, and the carboxyl-terminal half of EF-1δ were expressed, purified, and examined for protein:protein interactions by gel filtration chromatography and by a quartz-crystal microbalance method. An 80-kDa species containing EF-1β and γ subunits in a 1:1 molar ratio was detected by gel filtration. A higher molecular weight species containing an excess of EF-1γ relative to EF-1β was also detected. The amino-terminal region of EF-1β (amino acid residues 1-129) was sufficient for binding to EF-1γ. The carboxyl-terminal half of EF-1δ did not appear to form a complex with EF-1γ. © 2003 by Japan Society for Bioscience, Biotechnology, and Agrochemistry.