Premium
Characterization of the carbon starvation‐inducible and stationary phase‐inducible gene slp encoding an outer membrane lipoprotein in Escherichia coli
Author(s) -
Alexander Denise M.,
St John Ann C.
Publication year - 1994
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1994.tb00383.x
Subject(s) - biology , lac operon , escherichia coli , gene , microbiology and biotechnology , open reading frame , gene expression , sigma factor , reporter gene , signal peptide , peptide sequence , biochemistry , promoter
Summary Escherichia coli induces the expression of more than 50 proteins in response to starvation for a carbon source. Strains MC7 ( csi7::phoA ) and MC19 ( csi19::phoA ) contain fusions of a signal peptide‐deficient phoA reporter sequence to a csi ( c arbon s tarvation‐ i nducible) gene. PhoA expression increased when these strains were deprived of a carbon source or entered stationary phase but did not when the cells were deprived of a nitrogen source or subjected to osmotic, oxidative or thermal stress. Mapping and sequence analysis of the cloned phoA fusions in strains MC7 and MC19 indicated that they had occurred in different locations within the same previously unidentified gene. The wild‐type allele of this gene was cloned and the encoded protein was found to be a new lipoprotein. Therefore we propose to call this locus slp ( s tarvation l ipo p rotein). The 22 kDa Slp protein is associated with the outer membrane fraction. The slp gene was located at 78.6 centisomes on the E. coli genetic map. The ‐10 and ‐35 regions upstream of the mRNA start site were characteristic of a σ 70 promoter. The major transcript from this promoter was sufficiently large to contain slp sequences but not the downstream open reading frame. Induction of β‐galactosidase activity from a slp::lacZ translational fusion during carbon starvation or stationary phase was independent of cAMP, RpoS (KatF) and DnaK, all of which are known to affect the expression of certain starvation‐inducible or stationary phase‐inducible proteins.