title: The three S-layer-like homology motifs of the S-layer protein SbpA of Bacillus sphaericus CCM 2177 are not sufficient for binding to the pyruvylated secondary cell wall polymer.
abstract: The S-layer protein SbpA of Bacillus sphaericus CCM 2177 recognizes a pyruvylated secondary cell wall polymer (SCWP) as anchoring structure to the peptidoglycan-containing layer. Data analysis from surface plasmon resonance (SPR) spectroscopy revealed the existence of three different binding sites with high, medium and low affinity for rSbpA on SCWP immobilized to the sensor chip. The shortest C-terminal truncation with specific affinity to SCWP was rSbpA(31-318). Surprisingly, rSbpA(31-202) comprising the three S-layer-like homology (SLH) motifs did not bind at all. Analysis of the SbpA sequence revealed a 58-amino-acid-long SLH-like motif starting 11 amino acids after the third SLH motif. The importance of this motif for reconstituting the functional SCWP-binding domain was further demonstrated by construction of a chimaeric protein consisting of the SLH domain of SbsB, the S-layer protein of Geobacillus stearothermophilus PV72/p2 and the C-terminal part of SbpA. In contrast to SbsB or its SLH domain which did not recognize SCWP of B. sphaericus CCM 2177 as binding site, the chimaeric protein showed specific affinity. Deletion of 213 C-terminal amino acids of SbpA had no impact on the square (p4) lattice structure, whereas deletion of 350 amino acids was linked to a change in lattice type from square to oblique (p1).
authors.affiliation: BMT-Biomolecular Therapeutics GmbH, Brunner Strasse 59, A-1235 Vienna, Austria.
authors.forename: Carina
authors.initials: C
authors.lastname: Huber
authors.forename: Nicola
authors.initials: N
authors.lastname: Ilk
authors.forename: Dominik
authors.initials: D
authors.lastname: Rünzler
authors.forename: Eva M
authors.initials: EM
authors.lastname: Egelseer
authors.forename: Stefan
authors.initials: S
authors.lastname: Weigert
authors.forename: Uwe B
authors.initials: UB
authors.lastname: Sleytr
authors.forename: Margit
authors.initials: M
authors.lastname: Sára
mesh_terms: D000595:Amino Acid Sequence; D001407:Bacillus / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D001704:Biopolymers / Q000378:metabolism; D002473:Cell Wall / Q000737:chemistry / Q000378:metabolism; D003001:Cloning, Molecular; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D020349:Surface Plasmon Resonance
chemical_list: D001426:Bacterial Proteins; D001704:Biopolymers; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D011993:Recombinant Fusion Proteins; C055764:S-layer proteins; C120455:SbpA protein, bacteria; C104635:SbsB protein, Bacillus stearothermophilus