PDBsum entry 5hdl

Cell adhesion

PDB id: 5hdl

Contents

Protein chains

265 a.a.

Waters ×171

PDB id:

5hdl

Name:

Cell adhesion

Title:

Crystal structure of shaft pilin spaa from lactobacillus rhamnosus gg - e269a mutant

Structure:

Cell surface protein spaa. Chain: a, b, c. Fragment: unp residues 35-302. Engineered: yes. Mutation: yes

Source:

Lactobacillus rhamnosus gg. Organism_taxid: 568703. Strain: gg. Atcc: 53103. Gene: lrhm_0426. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.39Å R-factor: 0.220 R-free: 0.237

Authors:

P.Chaurasia,S.Pratap,I.Von Ossowski,A.Palva,V.Krishnan

Key ref:

P.Chaurasia et al. (2016). New insights about pilus formation in gut-adapted Lactobacillus rhamnosus GG from the crystal structure of the SpaA backbone-pilin subunit. Sci Rep, 6, 28664. PubMed id: 27349405 DOI: 10.1038/srep28664

Date:

05-Jan-16 Release date: 20-Jul-16

Protein chains

C7T9P4  (C7T9P4_LACRG) -

DOI no: 10.1038/srep28664

Sci Rep 6:28664 (2016)

PubMed id: 27349405

New insights about pilus formation in gut-adapted Lactobacillus rhamnosus GG from the crystal structure of the SpaA backbone-pilin subunit.

P.Chaurasia, S.Pratap, I.von Ossowski, A.Palva, V.Krishnan.

ABSTRACT

Thus far, all solved structures of pilin-proteins comprising sortase-assembled pili are from pathogenic genera and species. Here, we present the first crystal structure of a pilin subunit (SpaA) from a non-pathogen host (Lactobacillus rhamnosus GG). SpaA consists of two tandem CnaB-type domains, each with an isopeptide bond and E-box motif. Intriguingly, while the isopeptide bond in the N-terminal domain forms between lysine and asparagine, the one in the C-terminal domain atypically involves aspartate. We also solved crystal structures of mutant proteins where residues implicated in forming isopeptide bonds were replaced. Expectedly, the E-box-substituted E139A mutant lacks an isopeptide bond in the N-terminal domain. However, the C-terminal E269A substitution gave two structures; one of both domains with their isopeptide bonds present, and another of only the N-terminal domain, but with an unformed isopeptide bond and significant conformational changes. This latter crystal structure has never been observed for any other Gram-positive pilin. Notably, the C-terminal isopeptide bond still forms in D295N-substituted SpaA, irrespective of E269 being present or absent. Although E-box mutations affect SpaA proteolytic and thermal stability, a cumulative effect perturbing normal pilus polymerization was unobserved. A model showing the polymerized arrangement of SpaA within the SpaCBA pilus is proposed.