Altered Translation Initiation Factor 2 in the Cold-sensitive SsyG Mutant Affects Protein Export in Escherichia Coli
Overview
Molecular Biology
Authors
Affiliations
The Escherichia coli gene secY (pr1A) codes for an integral membrane protein that plays an essential role in protein export. We previously isolated cold-sensitive mutations (ssy) as extragenic suppressors of temperature-sensitive secY24 mutation. Now we show that the ssyG class of mutations are within infB coding for the translation initiation factor IF2. The mutants produce altered forms of IF2 with a cold-sensitive in vitro activity to form a translation initiation complex. The mutation suppresses not only secY24 but also other secretion-defective mutations such as secA51 and rp10215. The beta-galactosidase enzyme activity of the MalE-LacZ 72-47 hybrid protein is strikingly reduced in the ssyG mutant at the permissive high temperature, while the hybrid protein itself is normally synthesized. This effect, which was observed only for the hybrid protein with a functional signal sequence, may result from some alteration in the cellular localization of the protein. These results suggest that IF2 or the translation initiation step can modulate protein export reactions. The isolation of cold-sensitive ssyG mutations in infB provides genetic evidence that IF2 is indeed essential for normal growth of E. coli cells.
Salt-Specific Suppression of the Cold Denaturation of Thermophilic Multidomain Initiation Factor 2.
Dzupponova V, Tomaskova N, Antosova A, Sedlak E, Zoldak G Int J Mol Sci. 2023; 24(7).
PMID: 37047761 PMC: 10094840. DOI: 10.3390/ijms24076787.
Transcription complexes as RNA chaperones.
Said N, Wahl M Transcription. 2021; 12(4):126-155.
PMID: 34719334 PMC: 8632103. DOI: 10.1080/21541264.2021.1985931.
Zhao L, Cui Y, Fu G, Xu Z, Liao X, Zhang D mBio. 2021; 12(1).
PMID: 33436432 PMC: 7844537. DOI: 10.1128/mBio.02373-20.
Brandi A, Piersimoni L, Feto N, Spurio R, Alix J, Schmidt F Nucleic Acids Res. 2019; 47(9):4652-4662.
PMID: 30916323 PMC: 6511846. DOI: 10.1093/nar/gkz188.
Bubunenko M, Court D, Al Refaii A, Saxena S, Korepanov A, Friedman D Mol Microbiol. 2012; 87(2):382-93.
PMID: 23190053 PMC: 3545037. DOI: 10.1111/mmi.12105.