9uvr

Crystal structure of SSA1632 from Streptococcus sanguinis

spinqualitylabelsall models 9uvr, resolution 3.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9uvr is a 2 chain structure with sequence from Streptococcus sanguinis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 3.2Å Ligands: CD, GOL Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function A3CPB5_STRSV Publication Abstract from PubMed Bacterial pili are proteinaceous polymers that facilitate diverse biological functions. The SK36 strain of oral commensal bacterium Streptococcus sanguinis harbors sortase-assembled pili consisting of four proteins; PilA, PilB, PilC, and PilX. However, details regarding their structures and assembly mechanisms remain unclear. The crystal structures of recombinant PilA and PilB backbone pilins were examined at resolutions of 3.2 A and 1.8 A, respectively. Both exhibit a three-domain architecture (domains 1-3 from N- to C- terminus) with intramolecular isopeptide bonds in domains 2 and 3, and a positively charged, highly hydrophobic cleft in domain 1. Notably, while alignment along the same axis within the crystal was noted, their molecular orientations differ, as PilA maintains identical orientations (linear form), whereas PilB molecules are flipped 180 degrees relative to each other (helical form). Both recognize the conserved ALLPNT sequence of domain 3 via the domain 1 cleft. Fragment molecular orbital calculations revealed no significant energetic differences between the linear and helical forms, with interactions predominantly mediated by C-terminal asparagine and threonine residues. Immunoblot analysis confirmed intermolecular isopeptide bond formation between threonine and conserved lysine residues at the domain 1-2 interface. The preceding glycine residue in the GALLPNT sequence may serve as a flexible pivot, enabling transitions between both forms. Since PilA, PilB, and PilC contain the GALLPNT sequence and could interconnect, the observations of domain 1-mediated recognition of the domain 3 C-terminal region indicate a fundamental mechanism governing S. sanguinis pilus assembly. These findings provide molecular-based insight into sortase-mediated pilus biogenesis in Gram-positive bacteria. Combined structural and FMO-based insights into shaft pilin polymerization mechanism in Streptococcus sanguinis.,Takebe K, Miyakawa S, Sangawa T, Suzuki M, Matsumoto A, Oogai Y, Yamaguchi M, Sumitomo T, Fukuzawa K, Kawabata S, Nakata M Int J Biol Macromol. 2025 Dec;332(Pt 2):148264. doi: , 10.1016/j.ijbiomac.2025.148264. Epub 2025 Oct 12. PMID:41086886 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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