6OM5 image
Deposition Date 2019-04-18
Release Date 2019-12-04
Last Version Date 2024-03-13
Entry Detail
PDB ID:
6OM5
Keywords:
Title:
Structure of a haemophore from Haemophilus haemolyticus
Biological Source:
Source Organism:
Method Details:
Experimental Method:
Resolution:
1.60 Å
R-Value Free:
0.18
R-Value Work:
0.17
R-Value Observed:
0.17
Space Group:
P 32 2 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:haemophore
Chain IDs:A
Chain Length:254
Number of Molecules:1
Biological Source:Haemophilus haemolyticus M19107
Primary Citation
A heme-binding protein produced by Haemophilus haemolyticus inhibits non-typeable Haemophilus influenzae.
Mol.Microbiol. 113 381 398 (2020)
PMID: 31742788 DOI: 10.1111/mmi.14426

Abstact

Commensal bacteria serve as an important line of defense against colonisation by opportunisitic pathogens, but the underlying molecular mechanisms remain poorly explored. Here, we show that strains of a commensal bacterium, Haemophilus haemolyticus, make hemophilin, a heme-binding protein that inhibits growth of the opportunistic pathogen, non-typeable Haemophilus influenzae (NTHi) in culture. We purified the NTHi-inhibitory protein from H. haemolyticus and identified the hemophilin gene using proteomics and a gene knockout. An x-ray crystal structure of recombinant hemophilin shows that the protein does not belong to any of the known heme-binding protein folds, suggesting that it evolved independently. Biochemical characterisation shows that heme can be captured in the ferrous or ferric state, and with a variety of small heme-ligands bound, suggesting that hemophilin could function under a range of physiological conditions. Hemophilin knockout bacteria show a limited capacity to utilise free heme for growth. Our data suggest that hemophilin is a hemophore and that inhibition of NTHi occurs by heme starvation, raising the possibility that competition from hemophilin-producing H. haemolyticus could antagonise NTHi colonisation in the respiratory tract.

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