Serratia marcescens S-layer protein is secreted extracellularly via an ATP-binding cassette exporter, the Lip system.
The Serratia marcescens Lip exporter belonging to the ATP-binding cassette (ABC) exporter is known to be involved in signal peptide-independent extracellular secretion of a lipase and a metalloprotease. Although the genes of secretory proteins and their ABC exporters are usually all reported to be linked in several gram-negative bacteria, neither the lipase nor the protease gene is located close to the Lip exporter genes, lipBCD. A gene (slaA) located upstream of the lipBCD genes was cloned, revealing that it encodes a polypeptide of 100 kDa and is partially similar to the Caulobacter crescentus paracrystalline cell surface layer (S-layer) protein. The Lip exporter-deficient mutants of S. marcescens failed to secrete the SlaA protein. Electron micrography demonstrated the cell surface layer of S. marcescens. The S-layer protein was secreted to the cultured media in Escherichia coli cells carrying the Lip exporter. Three ABC exporters, Prt, Has and Hly systems, could not allow the S-layer secretion, indicating that the S. marcescens S-layer protein is strictly recognized by the Lip system. This is the first report concerning secretion of an S-layer protein via its own secretion system.
Kawai
E
E
Lead Generation Research Laboratory, Tanabe Seiyaku Co., Ltd, Osaka, Japan.
Akatsuka
H
H
Idei
A
A
Shibatani
T
T
Omori
K
K
D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D015153:Blotting, Western; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D008049:Lipase / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000378:metabolism; D015183:Restriction Mapping; D016415:Sequence Alignment; D017421:Sequence Analysis; D012706:Serratia marcescens / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D008565:Membrane Proteins; D011994:Recombinant Proteins; C112322:SlaA protein, Serratia marcescens; D008049:Lipase