Stationary phase expression of a novel Escherichia coli outer membrane lipoprotein and its relationship with mammalian apolipoprotein D. Implications for the origin of lipocalins.
We report a novel outer membrane lipoprotein of Escherichia coli. DNA sequencing between ampC and sugE at the 94.5 min region of the E. coli chromosome revealed an open reading frame specifying 177 amino acid residues. Primer extension analysis demonstrated that the promoter is activated at the transition between exponential and stationary growth phases under control of the rpoS sigma factor gene, and this was confirmed in vivo by monitoring expression of beta-galactosidase activity from a lacZ translational fusion. The amino acid sequence exhibited 31% identity with human apolipoprotein D (apoD), which is a component of plasma high density lipoprotein and belongs to the eukaryotic family of lipocalins. The bacterial lipocalin (Blc) contained a short deletion of 7 amino acid residues corresponding to a hydrophobic surface loop that is thought to facilitate the physical interaction between apoD and high density lipoprotein. However, Blc exhibited a typical prokaryotic lipoprotein signal peptide at its amino terminus. Overexpression, membrane fractionation, and metabolic labeling with [3H]palmitate demonstrated that Blc is indeed a globomycin-sensitive outer membrane lipoprotein. Blc represents the first bacterial member of the family of lipocalins and may serve a starvation response function in E. coli.
Bishop
R E
RE
Medical Research Council Group in the Molecular Biology of Membranes, University of Alberta, Edmonton, Canada.
Penfold
S S
SS
Frost
L S
LS
Höltje
J V
JV
Weiner
J H
JH
D000465:Algorithms; D000595:Amino Acid Sequence; D000818:Animals; D001053:Apolipoproteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D053399:Apolipoproteins D; D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002876:Chromosomes, Bacterial; D017931:DNA Primers; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D006801:Humans; D054834:Lipocalins; D008074:Lipoproteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics; D008322:Mammals; D008565:Membrane Proteins; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D001053:Apolipoproteins; D053399:Apolipoproteins D; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D017931:DNA Primers; D029968:Escherichia coli Proteins; D054834:Lipocalins; D008074:Lipoproteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D011993:Recombinant Fusion Proteins; C095894:blc protein, E coli; C080403:sugE protein, E coli