Alp suppression of Lon: dependence on the slpA gene.
We have previously found that plasmids carrying the Escherichia coli alp gene (now to be called alpA) suppress two phenotypes of a delta lon protease mutant, overproduction of capsular polysaccharide and sensitivity to UV light. Suppression of these lon phenotypes is most likely explained by the increased degradation of the Lon substrates responsible for these phenotypes. We have called this suppressing protease activity Alp protease. The Alp protease activity is detected in cells after introduction of plasmids carrying the alpA gene, which encodes an open reading frame of 70 amino acids. Insertions which abolish Alp activity interrupt this open reading frame. We have used Tn10 and lambda placMu mutagenesis to identify a chromosomal locus, slpA, that is required for alpA+ suppression of delta lon. This locus maps at 57 min, close to the chromosomal location of alpA. The expression of beta-galactosidase from a lac transcriptional fusion to slpA is increased six- to eightfold when the alpA+ gene is present on a multicopy plasmid. Therefore, AlpA acts as a transcriptional regulator of the slpA gene(s); activation of slpA transcription is necessary to suppress the phenotypes of a delta lon mutation. In an accompanying paper (J. E. Kirby, J. E. Trempy, and S. Gottesman, J. Bacteriol. 176:2068-2081, 1994), we show that neither AlpA nor SlpA is a component of the protease itself but that they are part of a regulatory cascade which leads to expression of the Alp protease.
Trempy
J E
JE
Laboratory of Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892.
Kirby
J E
JE
Gottesman
S
S
D049069:ATP-Dependent Proteases; D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001426:Bacterial Proteins; D001483:Base Sequence; D015139:Blotting, Southern; D003090:Coliphages / Q000235:genetics; D004252:DNA Mutational Analysis; D010450:Endopeptidases / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics; D006360:Heat-Shock Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D049070:Protease La; D011533:Proviruses / Q000235:genetics; D012329:RNA, Bacterial / Q000235:genetics; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000235:genetics*; D013489:Suppression, Genetic; D014157:Transcription Factors / Q000235:genetics*
C086513:AlpA protein, E coli; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D012329:RNA, Bacterial; D014157:Transcription Factors; C070683:surface layer protein A, Bacteria; D010450:Endopeptidases; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases; C483567:Lon protein, E coli; D049070:Protease La; C086514:Alp protease