Temperature-dependent regulation of the Ochrobactrum anthropi proteome

Ochrobactrum anthropi is a Gram-negative rod belonging to the Brucellaceaefamily, able to colonize a variety of environments, and actually reported as ahuman opportunistic pathogen. Despite its low virulence, the bacterium causes agrowing number of hospital-acquired infections mainly, but not exclusively, inimmunocompromised patients. The aim of this study was to obtain an overview ofthe global proteome changes occurring in O. anthropi in response to differentgrowth temperatures, in order to achieve a major understanding of the mechanisms by which the bacterium adapts to different habitats and to identify somepotential virulence factors. Combined quantitative mass spectrometry-basedproteomics and bioinformatics approaches were carried out on two O. anthropistrains grown at temperatures miming soil/plants habitat (25°C) and human hostenvironment (37°C), respectively. Proteomic analysis led to the identification ofover 150 differentially expressed proteins in both strains, out of over 1200total protein identifications. Among them, proteins responsible for heat shockresponse (DnaK, GrpE), motility (FliC, FlgG, FlgE), and putative virulencefactors (TolB) were identified. The study represents the first quantitativeproteomic analysis of O. anthropi performed by high-resolution quantitative mass spectrometry.