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TTG as the Initiation Codon of Salmonella slyA , a Gene Required for Survival within Macrophages
Author(s) -
Kawakami Takatoshi,
Kaneko Aki,
Okada Nobuhiko,
ImajohOhmi Shinobu,
aka Takeshi,
Matsui Hidenori,
Kawahara Kazuyoshi,
Danbara Hirofumi
Publication year - 1999
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.1999.tb02415.x
Subject(s) - biology , gene , codon usage bias , start codon , salmonella , genetics , translation (biology) , translational efficiency , silent mutation , stop codon , mutation , microbiology and biotechnology , messenger rna , genome , bacteria , missense mutation
The slyA gene, which has been implicated in the virulence of Salmonella serovar Typhimurium and its survival in macrophages, is widely distributed among different Salmonella serovars. In this study, we cloned and sequenced the translational initiation region of the slyA gene from nine different serovars and found sequence differences in the previously proposed ATG initiation codon but not in a TTG triplet, another putative initiation codon in the slyA gene. Therefore, we determined the actual translational initiation site of the slyA gene by analyzing slyA genes with defined mutation in either the ATG or TTG sequences in an in vitro translation assay and a quantitative hemolytic assay in Escherichia coli . The replacement of TTG by TTC in the slyA gene significantly reduced both the amount of protein synthesized and the hemolytic activity of a transformed strain of E. coli , while replacement of ATG by ATC had no effect in these assays. In addition, the amino acid sequence analysis of the His‐tagged SlyA protein showed that it was identical with the amino acid sequence deduced from the 5′ end of the slyA gene with a TTG initiation codon. Our results suggest that TTG serves as the translational initiation codon for the slyA gene of Salmonella .