Identification of a Brucella periplasmic protein central for the adaptation to environmental changes

VALGUARNERA E; SPERA JM; ALTABE S; UGALDE JE

Rosario

Congreso; L Annual Meeting of the Argentinean Society for Research in Biochemistry and Molecular Biology; 2014

UNR

All organisms, including bacteria, face constant environmental changes and must adapt to them in order to survive. In particular, many pathogens that alternate between free living conditions and their hosts, encounter different environments which vary in temperature, nutrient availability and presence of an immune system among other stimuli. In order to adapt to each of these scenarios, pathogenic bacteria must be able to sense the cues present in each of them and modify their biology appropriately. Here, we present the identification in Brucella of a gene (cgpA) that codes for a small protein with a periplasmic localization. A null mutant in cgpA is unable to replicate at 23°C in solid media and, in liquid media, is incapable of transitioning from lag to log phase, although at 37°C the strain grows as the wild type one in both conditions, indicating that the mutant is unable to sense and respond to the temperature shift. Lipid composition analysis of both strains at 37°C and 23°C indicated that the mutant is also unable to modify its membrane content in response to temperature. Moreover, the mutant strain is severely attenuated in macrophages but overreplicates in mice, inducing a heightened inflammatory response. Overall, our results indicate that cgpA codes for a protein that is key for the capacity of the bacteria to sense and respond to a plethora of extracellular cues.