PDBsum entry 1ywm

Surface active protein

PDB id: 1ywm

Contents

Protein chain

180 a.a. *

Ligands

DTU

GOL ×2

Waters ×222

* Residue conservation analysis

PDB id:

1ywm

Name:

Surface active protein

Title:

Crystal structure of the n-terminal domain of group b streptococcus alpha c protein

Structure:

C protein alpha-antigen. Chain: a. Fragment: n-terminal domain. Engineered: yes

Source:

Streptococcus agalactiae. Organism_taxid: 205921. Strain: a909. Gene: bca. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

1.86Å R-factor: 0.193 R-free: 0.233

Authors:

T.C.Auperin,G.R.Bolduc,M.J.Baron,A.Heroux,D.J.Filman,L.C.Madoff, J.M.Hogle

Key ref:

T.C.Aupérin et al. (2005). Crystal structure of the N-terminal domain of the group B streptococcus alpha C protein. J Biol Chem, 280, 18245-18252. PubMed id: 15753100 DOI: 10.1074/jbc.M412391200

Date:

18-Feb-05 Release date: 08-Mar-05

Protein chain

Q02192  (BCA_STRA1) -  C protein alpha-antigen from Streptococcus agalactiae serotype Ia (strain ATCC 27591 / A909 / CDC SS700)

Seq: 1020 a.a.

Struc: 180 a.a.*

* PDB and UniProt seqs differ at 11 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1074/jbc.M412391200

J Biol Chem 280:18245-18252 (2005)

PubMed id: 15753100

Crystal structure of the N-terminal domain of the group B streptococcus alpha C protein.

T.C.Aupérin, G.R.Bolduc, M.J.Baron, A.Heroux, D.J.Filman, L.C.Madoff, J.M.Hogle.

ABSTRACT

Group B Streptococcus (GBS) is the leading cause of bacterial pneumonia, sepsis, and meningitis among neonates and an important cause of morbidity among pregnant women and immunocompromised adults. Invasive diseases due to GBS are attributed to the ability of the pathogen to translocate across human epithelial surfaces. The alpha C protein (ACP) has been identified as an invasin that plays a role in internalization and translocation of GBS across epithelial cells. The soluble N-terminal domain of ACP (NtACP) blocks the internalization of GBS. We determined the 1.86-A resolution crystal structure of NtACP comprising residues Ser(52) through Leu(225) of the full-length ACP. NtACP has two domains, an N-terminal beta-sandwich and a C-terminal three-helix bundle. Structural and topological alignments reveal that the beta-sandwich shares structural elements with the type III fibronectin fold (FnIII), but includes structural elaborations that make it unique. We have identified a potential integrin-binding motif consisting of Lys-Thr-Asp(146), Arg(110), and Asp(118). A similar arrangement of charged residues has been described in other invasins. ACP shows a heparin binding activity that requires NtACP. We propose a possible heparin-binding site, including one surface of the three-helix bundle, and nearby portions of the sandwich and repeat domains. We have validated this prediction using assays of the heparin binding and cell-adhesion properties of engineered fragments of ACP. This is the first crystal structure of a member of the highly conserved Gram-positive surface alpha-like protein family, and it will enable the internalization mechanism of GBS to be dissected at the atomic level.

Selected figure(s)

Figure 2.
FIG. 2. Stereo ribbon representation of the structure of the N-terminal domain of S. agalactiae Alpha C protein. -sheets are shown in burgundy, -helices in blue, and 3[10]-helices in green. Figures were drawn with RIBBONS (67) and rendered with POV-Ray.

Figure 5.
FIG. 5. Molecular surface representation of the N-terminal domain of alpha C protein. The views are related by a rotation of 180° about the vertical axis. The structure exhibits a highly acidic surface (red). However, we have identified two positively charged clusters, BR1 and BR2 (blue), as potential glycosaminoglycan-binding sites. Figures were drawn with GRASP (70).

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2005, 280, 18245-18252) copyright 2005.

Figures were selected by an automated process.