Excision of a P4-like cryptic prophage leads to Alp protease expression in Escherichia coli.

摘要: Abstract The Escherichia coli K-12 alpA gene product, when overproduced from a multicopy plasmid, leads to suppression of the capsule overproduction and UV sensitivity phenotypes cells mutant for Lon ATP-dependent protease. This has previously been shown correlate with increased in vivo activity unknown energy-dependent proteolytic capable degrading substrates, Alp We show an accompanying paper that alpA, which homology short open reading frame bacteriophage P4, acts as positive transcriptional regulator slpA, linked necessary lon mutants (J. E. Trempy, J. Kirby, S. Gottesman, Bacteriol. 176:2061-2067). The sequence slpA suggests it encodes integrase closely related P4 int both are part cryptic P4-like prophage. AlpA expression increases SlpA synthesis. Increased leads, turn, excision loss Excision is dependent on integration host factor well SlpA. Prophage but not sufficient full A second function (named AHA) allows protease expression; this can be provided by kanamycin resistance element Tn903 present plasmid. prophage apparently allow inactivating small stable RNA (10Sa RNA) encoded ssrA gene. precursor its 3' end within prophage; mature lies attL site. Inactivation insertional mutagenesis suppressing protease, even presence Therefore, 10Sa negative synthesis or activity, must inactivate inhibitory RNA.