Characteristics of the surface-located carbohydrate-binding protein CbpC from Streptomyces coelicolor A32.
Streptomyces coelicolor A32 produces a 35.6-kDa carbohydrate-binding protein (named CbpC) in the presence of cellobiose, cellulose or chitin as sole carbon source. The protein was found secreted (a typical signal sequence was present at the N-terminus) and linked to the peptidoglycan layer of the mycelia. At its C-terminal end a putative cell-wall sorting signal was identified, consisting of (1) Streptomyces specific recognition site for a transpeptidase (LAETG instead of generic LPXTP consensus), (2) a hydrophobic region and (3) a tail of positively charged residues. The deletion of this sorting signal abolished the cell-wall attachment because the resulting CbpC-form was found extracellular. After purification this protein was shown to interact strongly with crystalline cellulose; different crystalline chitin-forms were recognised moderately and chitosan not. As demonstrated by analysing further truncated CbpC-forms a glycine-aspartate/serine rich region, which separates the carbohydrate-binding module from the sorting signal, plays an important role in protein stability.
Walter
Stefan
S
FB Biologie/Chemie, Universität Osnabrück, Barbarastr 11, 49069 Osnabrück, Germany. stefan.walter@uni-osnabrueck.de
Schrempf
Hildgund
H
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D002473:Cell Wall / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D011485:Protein Binding; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D048372:Streptomyces coelicolor / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
D001426:Bacterial Proteins; D021382:Protein Sorting Signals; D011956:Receptors, Cell Surface; C055213:saccharide-binding proteins