Novel structure of the N-terminal helical domain of BibA, a group B streptococcus immunogenic bacterial adhesin
(2020) In Acta crystallographica. Section D, Structural biology 76. p.759-770- Abstract
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... (More)
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 α-chain, as indicated by the decreased binding of BibA to a ΔCCP1 C4BP α-chain mutant. In summary, it is suggested that the GBS surface protein BibA, which consists of three antiparallel α-helical-bundle motifs, is unique and belongs to a new class of Gram-positive surface adhesins.
(Less)
- author
- Manne, Kartik ; Chattopadhyay, Debasish ; Agarwal, Vaibhav LU ; Blom, Anna M. LU ; Khare, Baldeep ; Chakravarthy, Srinivas ; Chang, Chungyu ; Ton-That, Hung and Narayana, Sthanam V.L.
- organization
- publishing date
- 2020
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- BibA, C4b-binding proteins, group B streptococcus, immunogenic bacterial adhesins, three-helix-bundle-motif repeats
- in
- Acta crystallographica. Section D, Structural biology
- volume
- 76
- pages
- 12 pages
- publisher
- John Wiley & Sons Inc.
- external identifiers
-
- pmid:32744258
- scopus:85088908979
- ISSN
- 2059-7983
- DOI
- 10.1107/S2059798320008116
- language
- English
- LU publication?
- yes
- id
- 6ae81574-7cce-45c2-8461-fc4950250ced
- date added to LUP
- 2020-08-12 09:54:33
- date last changed
- 2024-08-22 02:47:38
@article{6ae81574-7cce-45c2-8461-fc4950250ced, abstract = {{<p>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 α-chain, as indicated by the decreased binding of BibA to a ΔCCP1 C4BP α-chain mutant. In summary, it is suggested that the GBS surface protein BibA, which consists of three antiparallel α-helical-bundle motifs, is unique and belongs to a new class of Gram-positive surface adhesins.</p>}}, author = {{Manne, Kartik and Chattopadhyay, Debasish and Agarwal, Vaibhav and Blom, Anna M. and Khare, Baldeep and Chakravarthy, Srinivas and Chang, Chungyu and Ton-That, Hung and Narayana, Sthanam V.L.}}, issn = {{2059-7983}}, keywords = {{BibA; C4b-binding proteins; group B streptococcus; immunogenic bacterial adhesins; three-helix-bundle-motif repeats}}, language = {{eng}}, pages = {{759--770}}, publisher = {{John Wiley & Sons Inc.}}, series = {{Acta crystallographica. Section D, Structural biology}}, title = {{Novel structure of the N-terminal helical domain of BibA, a group B streptococcus immunogenic bacterial adhesin}}, url = {{http://dx.doi.org/10.1107/S2059798320008116}}, doi = {{10.1107/S2059798320008116}}, volume = {{76}}, year = {{2020}}, }