Abstract
Recent studies have revealed that bacterial protein methylation is a widespread post-translational modification that is required for virulence in selected pathogenic bacteria. In particular, altered methylation of outer membrane proteins has been shown to modulate the effectiveness of the host immune response. In this study, two-dimensional gel electrophoresis combined with matrix-assisted laser desorption/ionization-time of flight mass spectrometry identified a Leptospira interrogans serovar Copenhageni strain Fiocruz L1-130 protein, corresponding to open reading frame (ORF) LIC11848, which undergoes extensive and differential methylation of glutamic acid residues. Immunofluorescence microscopy implicated LIC11848 as a surface-exposed outer membrane protein, prompting the designation OmpL32. Indirect immunofluorescence microscopy of golden Syrian hamster liver and kidney sections revealed expression of OmpL32 during colonization of these organs. Identification of methylated surface-exposed outer membrane proteins, such as OmpL32, provides a foundation for delineating the role of this post-translational modification in leptospiral virulence.