A proteomic analysis of the regulon of the NarP two-component regulatory system response regulator in the bovine pathogen Mannheimia haemolytica A1

Ichiro Inamoto,Reggie Lo

doi:10.1186/1756-0500-4-510

Abstract

BackgroundThe response of the NarQP two-component signal transduction system regulon in response to the presence of nitrate for the bovine pathogen Mannheimia haemolytica A1 was investigated by proteomic analysis. Total proteins from a narP mutant and the parent SH1217 grown with or without NaNO3 supplement were examined by ISO-DALT 2D electrophoresis and liquid chromatography-mass spectrometry.ResultsSeventeen proteins were differentially expressed in the parent strain SH1217 in response to the addition of NaNO3 to the growth media. These responses were absent in the narP mutant, indicating that the altered production of these proteins is mediated by NarPMh. Interestingly, NarPMh mediated the increased production of some proteins which are not generally associated with nitrate respiration, such as the iron transporters FbpA and YfeA. The increased production of proteins such as superoxide dismutase, SodA, and GAPDH were also observed. The increased production of these iron-regulated proteins by NarPMh is thought to enhance the swift establishment of the nitrate respiration mechanism of M. haemolytica during pathogenesis.ConclusionThe data suggested NarPMh acts as an important regulator which regulates the expression of a small set of proteins in response to nitrate availability. This may contribute to the prevalence of M. haemolytica A1 in its host during pathogenesis of BPP, through enhancing the effectiveness of nitrate respiration either directly or indirectly.

Highlights

The response of the NarQP two-component signal transduction system regulon in response to the presence of nitrate for the bovine pathogen Mannheimia haemolytica A1 was investigated by proteomic analysis
* Correspondence: rlo@uoguelph.ca Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada. Environmental stresses such as transportation, crowding and viral infection play a major role in the pathogenesis of bovine pneumonic pasteurellosis (BPP) [5]
The M. haemolytica A1 proteome Total proteins extracted from SH1217 grown without NaNO3 supplementation were applied to a 17 cm IEF strip and separated by isoelectric focusing

Summary

Introduction

The response of the NarQP two-component signal transduction system regulon in response to the presence of nitrate for the bovine pathogen Mannheimia haemolytica A1 was investigated by proteomic analysis. Mannheimia haemolytica A1 is a Gram-negative, nonmotile coccobacillus normally found in the upper respiratory tract of healthy calves This bacterium is an opportunistic pathogen which causes bovine pneumonic pasteurellosis (BPP), an acute pneumonia that often leads to death in the animals [1,2]. It has been estimated that over $1 billion is lost annually in North America due to this disease [3,4] Environmental stresses such as transportation, crowding and viral infection play a major role in the pathogenesis of BPP [5]. Exposure to these stress factors compromises the immune system of the animal allowing M. haemolytica A1 to multiply and infect the lung through aerosol and gravitational movement. Since M. haemolytica A1 is an opportunistic pathogen, expression of these virulence factors are likely to respond to specific environmental signal(s)

Methods

Results

Conclusion