The phoP genes of various bacteria were analyzed which included Shigella dysenteriae, Enterobacter cloacae, Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Shigella dysenteriae, Enterobacter cloacae, Serratia marscescens,
Proteus
mirabilis, Mycobacterium tuberculosis, M. bovis BCG, and Listeria monocytogenes. Intracellular pathogenic bacteria such as M. tuberculosis, M. bovis BCG, and L. monocytogenes did not contain phoP-like DNA sequences. Several enteric bacteria,
including
S. dysenteriae, E. cloacae, E. coli, and S. typhimurium, were revealed to have phoP-like sequences. These results suggest that these intracellular pathogenic bacteria have different mechanism of intracellular survival from S. typhimurium, which
are
not
dependent on phoP gene. The sizes of phoP-containing DNA fragments were analyzed by Southern hybridization, The phoP-containing fragment of S. dysenteriae were 16kb, 5.5 and 4 kb, 6.5 kb, or 26kb, when digsted by BamHI, EcoRI, EcoRV, and Hind Ⅲ,
respectively. The phoP-containing fragment of E. cloacae were 30kb, 11kb, or 4.7 and 1.33 kb, when digested by BamHI, EcoRI, EcoRV, or Hind Ⅲ, respectively Our results suggested that phoP-phoQ operons are highly conserved in enteric bacteria,
though
they could not survive in intracellular environment. The role of these in enteric bacteria should further be studied.
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