Molecular basis of the magnesium deprivation response in Salmonella typhimurium

SONCINI, F. C.; GARCÍA VÉSCOVI, E.; SOLOMON, F.; GROISMAN, E.A.

JOURNAL OF BACTERIOLOGY

American Society for Microbiology

Año: 1996 vol. 178 p. 5092 - 5099

0021-9193

The PhoP-PhoQ two-component system is essential for virulence in Salmonella typhimurium. This system controls expression of some 40 different proteins, yet most PhoP-regulated genes remain unknown. To identify PhoP-regulated genes, we isolated a library of 50,000 independent lac gene transcriptional fusion strains and investigated whether production of b-galactosidase was regulated by PhoP. We recovered 47 lac gene fusions that were activated and 7 that were repressed when PhoP was expressed. Analysis of 40 such fusions defined some 30 loci, including mgtA and mgtCB, which encode two of the three Mg21 uptake systems of S. typhimurium; ugd, encoding UDP-glucose dehydrogenase; phoP, indicative that the phoPQ operon is autoregulated; and an open reading frame encoding a protein with sequence similarity to VanX, a dipeptidase required for resistance to vancomycin. Transcription of PhoP-activated genes was regulated by the levels of Mg21 in a PhoP-dependent manner. Strains with mutations in phoP or phoQ were defective for growth in low-Mg21 media. The mgtA and mgtCB mutants reached lower optical densities than the wild-type strain in low-Mg21 liquid media but displayed normal growth on low-Mg21 solid media. Six PhoP-activated genes were identified as essential to form colonies on low-Mg21 solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.22mutants reached lower optical densities than the wild-type strain in low-Mg2phoP or phoQ were defective for growth in low-Mg2, encoding UDP-glucose dehydrogenase; phoP, indicative that the phoPQ operon is autoregulated; and an open reading frame encoding a protein with sequence similarity to VanX, a dipeptidase required for resistance to vancomycin. Transcription of PhoP-activated genes was regulated by the levels of Mg21 in a PhoP-dependent manner. Strains with mutations in phoP or phoQ were defective for growth in low-Mg21 media. The mgtA and mgtCB mutants reached lower optical densities than the wild-type strain in low-Mg21 liquid media but displayed normal growth on low-Mg21 solid media. Six PhoP-activated genes were identified as essential to form colonies on low-Mg21 solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.22mutants reached lower optical densities than the wild-type strain in low-Mg2phoP or phoQ were defective for growth in low-Mg22mgtA and mgtCB, which encode two of the three Mg2Salmonella typhimurium. This system controls expression of some 40 different proteins, yet most PhoP-regulated genes remain unknown. To identify PhoP-regulated genes, we isolated a library of 50,000 independent lac gene transcriptional fusion strains and investigated whether production of b-galactosidase was regulated by PhoP. We recovered 47 lac gene fusions that were activated and 7 that were repressed when PhoP was expressed. Analysis of 40 such fusions defined some 30 loci, including mgtA and mgtCB, which encode two of the three Mg21 uptake systems of S. typhimurium; ugd, encoding UDP-glucose dehydrogenase; phoP, indicative that the phoPQ operon is autoregulated; and an open reading frame encoding a protein with sequence similarity to VanX, a dipeptidase required for resistance to vancomycin. Transcription of PhoP-activated genes was regulated by the levels of Mg21 in a PhoP-dependent manner. Strains with mutations in phoP or phoQ were defective for growth in low-Mg21 media. The mgtA and mgtCB mutants reached lower optical densities than the wild-type strain in low-Mg21 liquid media but displayed normal growth on low-Mg21 solid media. Six PhoP-activated genes were identified as essential to form colonies on low-Mg21 solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.22mutants reached lower optical densities than the wild-type strain in low-Mg2phoP or phoQ were defective for growth in low-Mg2, encoding UDP-glucose dehydrogenase; phoP, indicative that the phoPQ operon is autoregulated; and an open reading frame encoding a protein with sequence similarity to VanX, a dipeptidase required for resistance to vancomycin. Transcription of PhoP-activated genes was regulated by the levels of Mg21 in a PhoP-dependent manner. Strains with mutations in phoP or phoQ were defective for growth in low-Mg21 media. The mgtA and mgtCB mutants reached lower optical densities than the wild-type strain in low-Mg21 liquid media but displayed normal growth on low-Mg21 solid media. Six PhoP-activated genes were identified as essential to form colonies on low-Mg21 solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.22mutants reached lower optical densities than the wild-type strain in low-Mg2phoP or phoQ were defective for growth in low-Mg22mgtA and mgtCB, which encode two of the three Mg2lac gene transcriptional fusion strains and investigated whether production of b-galactosidase was regulated by PhoP. We recovered 47 lac gene fusions that were activated and 7 that were repressed when PhoP was expressed. Analysis of 40 such fusions defined some 30 loci, including mgtA and mgtCB, which encode two of the three Mg21 uptake systems of S. typhimurium; ugd, encoding UDP-glucose dehydrogenase; phoP, indicative that the phoPQ operon is autoregulated; and an open reading frame encoding a protein with sequence similarity to VanX, a dipeptidase required for resistance to vancomycin. Transcription of PhoP-activated genes was regulated by the levels of Mg21 in a PhoP-dependent manner. Strains with mutations in phoP or phoQ were defective for growth in low-Mg21 media. The mgtA and mgtCB mutants reached lower optical densities than the wild-type strain in low-Mg21 liquid media but displayed normal growth on low-Mg21 solid media. Six PhoP-activated genes were identified as essential to form colonies on low-Mg21 solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.22mutants reached lower optical densities than the wild-type strain in low-Mg2phoP or phoQ were defective for growth in low-Mg2, encoding UDP-glucose dehydrogenase; phoP, indicative that the phoPQ operon is autoregulated; and an open reading frame encoding a protein with sequence similarity to VanX, a dipeptidase required for resistance to vancomycin. Transcription of PhoP-activated genes was regulated by the levels of Mg21 in a PhoP-dependent manner. Strains with mutations in phoP or phoQ were defective for growth in low-Mg21 media. The mgtA and mgtCB mutants reached lower optical densities than the wild-type strain in low-Mg21 liquid media but displayed normal growth on low-Mg21 solid media. Six PhoP-activated genes were identified as essential to form colonies on low-Mg21 solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.22mutants reached lower optical densities than the wild-type strain in low-Mg2phoP or phoQ were defective for growth in low-Mg22mgtA and mgtCB, which encode two of the three Mg2b-galactosidase was regulated by PhoP. We recovered 47 lac gene fusions that were activated and 7 that were repressed when PhoP was expressed. Analysis of 40 such fusions defined some 30 loci, including mgtA and mgtCB, which encode two of the three Mg21 uptake systems of S. typhimurium; ugd, encoding UDP-glucose dehydrogenase; phoP, indicative that the phoPQ operon is autoregulated; and an open reading frame encoding a protein with sequence similarity to VanX, a dipeptidase required for resistance to vancomycin. Transcription of PhoP-activated genes was regulated by the levels of Mg21 in a PhoP-dependent manner. Strains with mutations in phoP or phoQ were defective for growth in low-Mg21 media. The mgtA and mgtCB mutants reached lower optical densities than the wild-type strain in low-Mg21 liquid media but displayed normal growth on low-Mg21 solid media. Six PhoP-activated genes were identified as essential to form colonies on low-Mg21 solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.22mutants reached lower optical densities than the wild-type strain in low-Mg2phoP or phoQ were defective for growth in low-Mg2, encoding UDP-glucose dehydrogenase; phoP, indicative that the phoPQ operon is autoregulated; and an open reading frame encoding a protein with sequence similarity to VanX, a dipeptidase required for resistance to vancomycin. Transcription of PhoP-activated genes was regulated by the levels of Mg21 in a PhoP-dependent manner. Strains with mutations in phoP or phoQ were defective for growth in low-Mg21 media. The mgtA and mgtCB mutants reached lower optical densities than the wild-type strain in low-Mg21 liquid media but displayed normal growth on low-Mg21 solid media. Six PhoP-activated genes were identified as essential to form colonies on low-Mg21 solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.22mutants reached lower optical densities than the wild-type strain in low-Mg2phoP or phoQ were defective for growth in low-Mg22mgtA and mgtCB, which encode two of the three Mg21 uptake systems of S. typhimurium; ugd, encoding UDP-glucose dehydrogenase; phoP, indicative that the phoPQ operon is autoregulated; and an open reading frame encoding a protein with sequence similarity to VanX, a dipeptidase required for resistance to vancomycin. Transcription of PhoP-activated genes was regulated by the levels of Mg21 in a PhoP-dependent manner. Strains with mutations in phoP or phoQ were defective for growth in low-Mg21 media. The mgtA and mgtCB mutants reached lower optical densities than the wild-type strain in low-Mg21 liquid media but displayed normal growth on low-Mg21 solid media. Six PhoP-activated genes were identified as essential to form colonies on low-Mg21 solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.22mutants reached lower optical densities than the wild-type strain in low-Mg2phoP or phoQ were defective for growth in low-Mg2, encoding UDP-glucose dehydrogenase; phoP, indicative that the phoPQ operon is autoregulated; and an open reading frame encoding a protein with sequence similarity to VanX, a dipeptidase required for resistance to vancomycin. Transcription of PhoP-activated genes was regulated by the levels of Mg21 in a PhoP-dependent manner. Strains with mutations in phoP or phoQ were defective for growth in low-Mg21 media. The mgtA and mgtCB mutants reached lower optical densities than the wild-type strain in low-Mg21 liquid media but displayed normal growth on low-Mg21 solid media. Six PhoP-activated genes were identified as essential to form colonies on low-Mg21 solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.22mutants reached lower optical densities than the wild-type strain in low-Mg2phoP or phoQ were defective for growth in low-Mg221 in a PhoP-dependent manner. Strains with mutations in phoP or phoQ were defective for growth in low-Mg21 media. The mgtA and mgtCB mutants reached lower optical densities than the wild-type strain in low-Mg21 liquid media but displayed normal growth on low-Mg21 solid media. Six PhoP-activated genes were identified as essential to form colonies on low-Mg21 solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.22mutants reached lower optical densities than the wild-type strain in low-Mg2phoP or phoQ were defective for growth in low-Mg21 media. The mgtA and mgtCB mutants reached lower optical densities than the wild-type strain in low-Mg21 liquid media but displayed normal growth on low-Mg21 solid media. Six PhoP-activated genes were identified as essential to form colonies on low-Mg21 solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.22mutants reached lower optical densities than the wild-type strain in low-Mg21 liquid media but displayed normal growth on low-Mg21 solid media. Six PhoP-activated genes were identified as essential to form colonies on low-Mg21 solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.221 solid media. Six PhoP-activated genes were identified as essential to form colonies on low-Mg21 solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.21 solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.