A Gene Encoding l -Methionine γ-Lyase Is Present in Enterobacteriaceae Family Genomes: Identification and Characterization of Citrobacter freundii l -Methionine γ-Lyase

Abstract

ABSTRACT Citrobacter freundii cells produce l -methionine γ-lyase when grown on a medium containing l -methionine. The nucleotide sequence of the hybrid plasmid with a C. freundii EcoRI insert of about 3.0 kbp contained two open reading frames, consisting of 1,194 nucleotides and 1,296 nucleotides, respectively. The first one (denoted megL ) encoded l -methionine γ-lyase. The enzyme was overexpressed in Escherichia coli and purified. The second frame encoded a protein belonging to the family of permeases. Regions of high sequence identity with the 3′-terminal part of the C. freundii megL gene located in the same regions of Salmonella enterica serovar Typhimurium, Shigella flexneri , E. coli , and Citrobacter rodentium genomes were found.