A phosphotransferase system permease is a novel component of CadC signaling in Salmonella enterica.
In Salmonella enterica serovar Typhimurium, proteolytic cleavage of the membrane-bound transcriptional regulator CadC acts as a switch to activate genes of the lysine decarboxylase system in response to low pH and lysine signals. To identify the genetic factors required for the proteolytic activation of CadC, we performed genome-wide random mutagenesis. We show that a phosphotransferase system (PTS) permease STM4538 acts as a positive modulator of CadC function. The transposon insertion in STM4538 reduces the expression of the CadC target operon cadBA under permissive conditions. In addition, deletional inactivation of STM4538 in the wild-type background leads to the impaired proteolytic cleavage of CadC. We also show that only the low pH signal is involved in the proteolytic processing of CadC, but the lysine signal plays a role in the repression of the lysP gene encoding a lysine-specific permease, which negatively controls expression of the cadBA operon. Our data suggest that the PTS permease STM4538 affects proteolytic processing, which is a necessary but not sufficient step for CadC activation, rendering CadC able to activate target genes.
School of Life Sciences and Biotechnology, Korea University, Seoul, South Korea. ykpark@korea.ac.kr
Yong Heon
YH
Lee
Sinyeon
S
Kim
Ji Hye
JH
Kim
Iel Soo
IS
Bang
In Soo
IS
Lee
Seong Ho
SH
Bang
Yong Keun
YK
Park
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004251:DNA Transposable Elements; D015964:Gene Expression Regulation, Bacterial; D006863:Hydrogen-Ion Concentration; D008239:Lysine / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D009876:Operon; D010770:Phosphotransferases / Q000235:genetics / Q000378:metabolism*; D059748:Proteolysis; D012486:Salmonella typhimurium / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D026901:Membrane Transport Proteins; D015534:Trans-Activators; D010770:Phosphotransferases; D008239:Lysine