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Non-typeable Haemophilus influenzae (NTHi) is an important opportunistic pathogen of the human respiratory tract that has proved recalcitrant to vaccine development and shows increasing prevalence of antibiotic resistance, prompting us to search for alternative anti-microbial strategies. Haemophilus haemolyticus is closely related to NTHi, and also colonises the respiratory tract, but is recognised as a non-pathogenic commensal species. We identified two H. haemolyticusisolates secreting a 27-kDa protein that inhibited the growth of NTHi in vitro, but did not inhibit a range of other respiratory flora that were tested, suggesting a level of species-specificity against NTHi. A gene knockout established that the gene product of interest was responsible for inhibitory activity. Spectroscopic and x-ray crystallographic analysis of the recombinant protein identified a haem binding site. The protein shares structural features with some non-haem iron scavenging proteins, but the haem-binding site is unique. Insights into the biological function, including NTHi inhibitory actions, of this protein, based on structure, biochemistry and bioactivity assays are presented. The work is ongoing in the context that strains of H. haemolyticus might be developed as respiratory probiotics to combat colonisation and infection with NTHi.

Item Type:	Conference Extract
Keywords:	haem, haemophilus
Research Division:	Biomedical and Clinical Sciences
Research Group:	Medical microbiology
Research Field:	Medical bacteriology
Objective Division:	Health
Objective Group:	Clinical health
Objective Field:	Clinical health not elsewhere classified
UTAS Author:	Latham, RD (Mr Roger Latham)
UTAS Author:	Atto, B (Miss Brianna Atto)
UTAS Author:	Tristram, SG (Dr Stephen Tristram)
UTAS Author:	Gell, DA (Dr David Gell)
ID Code:	133603
Year Published:	2018
Deposited By:	Health Sciences
Deposited On:	2019-07-03
Last Modified:	2019-07-03
Downloads:	0