Insertion of an outer membrane protein in Escherichia coli requires a chaperone-like protein.
Only one of the characterized components of the main terminal branch of the general secretory pathway (GSP) in Gram-negative bacteria, GspD, is an integral outer membrane protein that could conceivably form a channel to permit protein transport across this membrane. PulD, a member of the GspD protein family required for pullulanase secretion by Klebsiella oxytoca, is shown here to form outer membrane-associated complexes which are not readily dissociated by SDS treatment. The outer membrane association of PulD is absolutely dependent on another component of the GSP, the outer membrane-anchored lipoprotein PulS. Furthermore, the absence of PulS resulted in limited proteolysis of PulD and caused induction of the so-called phage shock response, as measured by increased expression of the pspA gene. We propose that PulS may be the first member of a new family of periplasmic chaperones that are specifically required for the insertion of a group of outer membrane proteins into this membrane. PulS is only the second component of the main terminal branch of the GSP for which a precise function can be proposed.
Hardie
K R
KR
Unité de Génétique Moléculaire, CNRS URA 1149, Institut Pasteur, Paris, France.
Lory
S
S
Pugsley
A P
AP
D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D003001:Cloning, Molecular; D003090:Coliphages / Q000472:pathogenicity; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000821:virology; D029968:Escherichia coli Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism; D007709:Klebsiella / Q000378:metabolism; D008074:Lipoproteins / Q000378:metabolism; D046911:Macromolecular Substances; D018832:Molecular Chaperones / Q000378:metabolism*; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics
D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D008074:Lipoproteins; D046911:Macromolecular Substances; D018832:Molecular Chaperones; C560059:PulS protein, E coli; C061377:PulD protein, Klebsiella pneumoniae; D006026:Glycoside Hydrolases; C100181:pullulanase