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==Novel structure of the N-terminal helical domain of BibA, a group B streptococcus immunogenic bacterial adhesin==
<StructureSection load='6poo' size='340' side='right'caption='[[6poo]], [[Resolution|resolution]] 3.03&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6POO OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6POO FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 3.03&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MSE:SELENOMETHIONINE'>MSE</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=6poo FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6poo OCA], [https://pdbe.org/6poo PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6poo RCSB], [https://www.ebi.ac.uk/pdbsum/6poo PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6poo ProSAT]</span></td></tr>
</table>
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== Publication Abstract from PubMed ==
BibA, a group B streptococcus (GBS) surface protein, has been shown to protect the pathogen from phagocytic killing by sequestering a complement inhibitor: C4b-binding protein (C4BP). Here, the X-ray crystallographic structure of a GBS BibA fragment (BibA126-398) and a low-resolution small-angle X-ray scattering (SAXS) structure of the full-length N-terminal domain (BibA34-400) are described. The BibA126-398 fragment crystal structure displayed a novel and predominantly helical structure. The tertiary arrangement of helices forms four antiparallel three-helix-bundle-motif repeats, with one long helix from a bundle extending into the next. Multiple mutations on recombinant BibA34-400 delayed the degradation of the protein, and circular dichroism spectroscopy of BibA34-400 suggested a similar secondary-structure composition to that observed in the crystallized BibA126-398 fragment. A model was generated for the 92 N-terminal residues (BibA34-125) using structural similarity prediction programs, and a BibA34-400 model was generated by combining the coordinates of BibA34-126 and BibA126-398. The X-ray structure of BibA126-398 and the model of BibA34-400 fitted well into the calculated SAXS envelope. One possible binding site for the BibA N-terminal domain was localized to the N-terminal CCP (complement-control protein) domains of the C4BP alpha-chain, as indicated by the decreased binding of BibA to a DeltaCCP1 C4BP alpha-chain mutant. In summary, it is suggested that the GBS surface protein BibA, which consists of three antiparallel alpha-helical-bundle motifs, is unique and belongs to a new class of Gram-positive surface adhesins.

Novel structure of the N-terminal helical domain of BibA, a group B streptococcus immunogenic bacterial adhesin.,Manne K, Chattopadhyay D, Agarwal V, Blom AM, Khare B, Chakravarthy S, Chang C, Ton-That H, Narayana SVL Acta Crystallogr D Struct Biol. 2020 Aug 1;76(Pt 8):759-770. doi:, 10.1107/S2059798320008116. Epub 2020 Jul 27. PMID:32744258<ref>PMID:32744258</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Manne K]]
[[Category: Narayana SV]]