Oligomerization, membrane anchoring, and cellulose-binding characteristics of AbpS, a receptor-like Streptomyces protein.
Streptomyces reticuli produces a 34.6-kDa surface-anchored protein (AbpS) whose surface-exposed N terminus binds strongly to Avicel, a dominantly crystalline type of cellulose. The generation of a large set of mutated abpS-genes and the subsequent analysis of the corresponding proteins in vitro as well as in vivo in a Streptomyces host allow the assignment of the following characteristics for AbpS. (i) Amino acid residues participating directly in the cellulose-interaction are located at the N terminus. (ii) As ascertained by cross-linking experiments, AbpS forms homotetramers in its soluble as well as cellulose-bound form. (iii) The intermolecular assembly of four AbpS molecules is governed by two domains (including amino acids 60-110 and 161-212). Both domains possess large portions of alpha-helical regions in which hydrophobic amino acids are located on one side as known from coiled-coil proteins. (iv) The C-terminal part of AbpS comprising 35 amino acids contains a transmembrane domain. Due to the surface-exposed N terminus of AbpS and the presence of transmembrane helix the C terminus has to be situated in the cytoplasm of the S. reticuli hyphae. Thus AbpS connects the interior of the mycelia with the extracellular space and binds cellulose using a unique cellulose-binding module.
Fachbereich B Biologie/Chemie, Universität Osnabrück, 49069 Osnabrück, Germany. Stefan.Walter@uni-osnabrueck.de
Stefan
S
Walter
Hildgund
H
Schrempf
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D057927:Hydrophobic and Hydrophilic Interactions; D008969:Molecular Sequence Data; D008970:Molecular Weight; D020836:Protein Structure, Quaternary; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D013302:Streptomyces / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D002482:Cellulose