A Mycoplasma gallisepticum Glycerol ABC Transporter Involved in Pathogenicity

MalF has been shown to be required for virulence in the important avian pathogen To characterize the function of MalF, predicted to be part of a putative ABC transporter, we compared metabolite profiles of a mutant with a transposon inserted in (MalF-deficient ST mutant 04-1; Δ ) with those of wild-type bacteria using gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry. Of the substrates likely to be transported by an ABC transport system, glycerol was detected at significantly lower abundance in the Δ mutant, compared to the wild type. Stable isotope labeling using [U- C]glycerol and reverse transcription-quantitative PCR analysis indicated that MalF was responsible for the import of glycerol into and that, in the absence of MalF, the transcription of , which encodes a second transporter, GtsA, was upregulated, potentially to increase the import of glycerol-3-phosphate into the cell to compensate for the loss of MalF. The loss of MalF appeared to have a global effect on glycerol metabolism, suggesting that it may also play a regulatory role, and cellular morphology was also affected, indicating that the change to glycerol metabolism may have a broader effect on cellular organization. Overall, this study suggests that the reduced virulence of the Δ mutant is due to perturbed glycerol uptake and metabolism and that the operon including should be reannotated as to reflect its function in glycerol transport. Many mycoplasmas are pathogenic and cause disease in humans and animals. causes chronic respiratory disease in chickens and infectious sinusitis in turkeys, resulting in economic losses in poultry industries throughout the world. Expanding our knowledge about the pathogenesis of mycoplasma infections requires better understanding of the specific gene functions of these bacteria. In this study, we have characterized the metabolic function of a protein involved in the pathogenicity of , as well as its effect on expression of selected genes, cell phenotype, and H O production. This study is a key step forward in elucidating why this protein plays a key role in virulence in chickens. This study also emphasizes the importance of functional characterization of mycoplasma proteins, using tools such as metabolomics, since prediction of function based on homology to other bacterial proteins is not always accurate.