4RT6 image
Entry Detail
PDB ID:
4RT6
Keywords:
Title:
Structure of a complex between hemopexin and hemopexin binding protein
Biological Source:
PDB Version:
Deposition Date:
2014-11-13
Release Date:
2016-05-18
Method Details:
Experimental Method:
Resolution:
2.80 Å
R-Value Free:
0.22
R-Value Work:
0.17
R-Value Observed:
0.18
Space Group:
P 21 21 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Heme/hemopexin-binding protein
Mutations:C876S, C882S
Chain IDs:A
Chain Length:884
Number of Molecules:1
Biological Source:Haemophilus influenzae Rd KW20
Polymer Type:polypeptide(L)
Description:Hemopexin
Chain IDs:B
Chain Length:214
Number of Molecules:1
Biological Source:Oryctolagus cuniculus
Modified Residue
Compound ID Chain ID Parent Comp ID Details 2D Image
ASN B ASN GLYCOSYLATION SITE
Primary Citation
Structural basis for haem piracy from host haemopexin by Haemophilus influenzae.
Nat Commun 7 11590 11590 (2016)
PMID: 27188378 DOI: 10.1038/ncomms11590

Abstact

Haemophilus influenzae is an obligate human commensal/pathogen that requires haem for survival and can acquire it from several host haemoproteins, including haemopexin. The haem transport system from haem-haemopexin consists of HxuC, a haem receptor, and the two-partner-secretion system HxuB/HxuA. HxuA, which is exposed at the cell surface, is strictly required for haem acquisition from haemopexin. HxuA forms complexes with haem-haemopexin, leading to haem release and its capture by HxuC. The key question is how HxuA liberates haem from haemopexin. Here, we solve crystal structures of HxuA alone, and HxuA in complex with the N-terminal domain of haemopexin. A rational basis for the release of haem from haem-haemopexin is derived from both in vivo and in vitro studies. HxuA acts as a wedge that destabilizes the two-domains structure of haemopexin with a mobile loop on HxuA that favours haem ejection by redirecting key residues in the haem-binding pocket of haemopexin.

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Primary Citation of related structures