Poster Presentation BacPath 13: Molecular Analysis of Bacterial Pathogens Conference 2015

Lysine acetylation targets key metabolic enzymes and virulence factors of the anaerobe Porphyromonas gingivalis (#103)

Catherine A. Butler 1 , Paul D. Veith 1 , Matthew F. Nieto 1 , Stuart G. Dashper 1 , Eric C. Reynolds 1
  1. Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, VIC, Australia

Porphyromonas gingivalis is a Gram-negative anaerobe considered to be a keystone pathogen in the development of the bacterial-associated inflammatory oral disease chronic periodontitis. Although post-translational modifications (PTMs) of proteins are commonly found to modify protein functions in eukaryotes and prokaryotes, PTMs such as lysine acetylation have not been examined in P. gingivalis. Lysine acetylation is the addition of an acetyl group to a lysine which removes this amino acid’s positive charge and can induce changes in a protein’s secondary structure. This can alter a protein’s function or immunogenicity. Therefore a proteomics based approach combining immune-affinity enrichment with high sensitivity Orbitrap mass spectrometry was undertaken to identify the lysine acetylome of P. gingivalis. In total, 130 lysine acetylated peptides were identified from 92 P. gingivalis proteins. The majority of these peptides (71) were attributed to 45 proteins with predicted metabolic activity; these proteins could be mapped to several P. gingivalis metabolic pathways where enzymes catalysing sequential reactions within the same pathway were often found acetylated. Notably, the catabolic pathways of complex anaerobic fermentation of amino acids to produce energy had 12 enzymes lysine acetylated. Protein synthesis, in particular translation, was also targeted by lysine acetylation in P. gingivalis with the three translation elongation factors Tu, P and G, 11 ribosomal proteins and 5 tRNA synthetases all found to be acetylated. Secreted proteinases RgpA, RgpB and Kgp, collectively known as the gingipains and the major virulence factors of P. gingivalis, were also lysine acetylated. Taken together, this suggests that lysine acetylation may be an important mechanism in the virulence and metabolic regulation of P. gingivalis, which may affect this organism’s ability to cause disease and adapt its metabolism throughout infection.