OlpB, a new outer layer protein of Clostridium thermocellum, and binding of its S-layer-like domains to components of the cell envelope.
Several proteins of Clostridium thermocellum possess a C-terminal triplicated sequence related to bacterial cell surface proteins. This sequence was named the SLH domain (for S-layer homology), and it was proposed that it might serve to anchor proteins to the cell surface (A. Lupas, H. Engelhardt, J. Peters, U. Santarius, S. Volker, and W. Baumeister, J. Bacteriol. 176:1224-1233, 1994). This hypothesis was investigated by using the SLH-containing protein ORF1p from C. thermocellum as a model. Subcellular fractionation, immunoblotting, and electron microscopy of immunocytochemically labeled cells indicated that ORF1p was located on the surface of C. thermocellum. To detect C. thermocellum components interacting with the SLH domains of ORF1p, a probe was constructed by grafting these domains on the C terminus of the MalE protein of Escherichia coli. The SLH domains conferred on the chimeric protein (MalE-ORF1p-C) the ability to bind noncovalently to the peptidoglycan of C. thermocellum. In addition, 125I-labeled MalE-ORF1p-C was shown to bind to SLH-bearing proteins transferred onto nitrocellulose, and to a 26- to 28-kDa component of the cell envelope. These results agree with the hypothesis that SLH domains contribute to the binding of exocellular proteins to the cell surface of bacteria. The gene carrying ORF1 and its product, ORF1p, are renamed olpB and OlpB (for outer layer protein B), respectively.
Lemaire
M
M
Unité de Physiologie Cellulaire and URA 1300 CNRS, Département des Biotechnologies, Paris, France.
Ohayon
H
H
Gounon
P
P
Fujino
T
T
Béguin
P
P
D018528:ATP-Binding Cassette Transporters; D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D002458:Cell Fractionation; D002462:Cell Membrane / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D003013:Clostridium / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D029968:Escherichia coli Proteins; D015151:Immunoblotting; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D010457:Peptidoglycan / Q000378:metabolism; D033902:Periplasmic Binding Proteins; D011485:Protein Binding; D015202:Protein Engineering; D011993:Recombinant Fusion Proteins; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D013347:Subcellular Fractions / Q000737:chemistry
D018528:ATP-Binding Cassette Transporters; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C461619:MalE protein, E coli; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; C093327:OlpB protein, Clostridium thermocellum; D010457:Peptidoglycan; D033902:Periplasmic Binding Proteins; D011993:Recombinant Fusion Proteins; C461599:maltose transport system, E coli