Role s of Protein Acetylation in the Human Pathogen Helicobacter pylori

Abstract

Helicobacter pylori is a gram-negative epsilon proteobacterium infecting half of the world population. H. pylori is a naturally competent bacterium with a huge repertoire of Restriction-Modification (RM) systems. The bacterium lacks a mismatch DNA repair system, lexA gene responsible for SOS response, and starvation/stress-responding alternative sigma factor. These factors make it essential to understand the physiology of bacteria to manage H. pylori-related diseases. In recent years, protein acetylation stands out as a vital regulatory system of cellular processes such as virulence, acid stress survival, transcription, motility, and metabolic pathways. In this study, Western blotting-based acetylome analysis of different strains of H. pylori suggest a prominent and significantly different acetylation profile in H. pylori, strain. Mass spectrometry-based acetylome analysis found 384 acetylation sites on 236. HP0935, a possible protein N-acetyltransferase belonging to GNAT superfamily was identified. Unlike most GNAT superfamily acetyltransferases HP0935 remains as a monomer in the solution. Biochemical analysis suggests that HP0935 acetylates the respective N-and#945; amino group of lysine, arginine, methionine, and serine. In addition, HP0935 acetylates the N-and#949; amino group of lysine. Crystals of HP0935 were grown by the sitting drop vapor diffusion method, and the structure was solved to 1.93 Å resolution. The crystal structure of HP0935 showed a proper GNAT fold, which further validates that the protein belongs to the GNAT superfamily. The co-crystal structure of HP0935 and acetyl-CoA complex suggests that Glu77, His115, and Tyr127 and a conserved water molecule could play essential roles in the catalysis. In general, glutamate and histidine in most GNATs act as a general base that deprotonate the amino group of substrates. In other GNATs, conserved water molecules could perform a similar activity. Tyrosine in the structure acts as a general acid that protonates the leaving thiolate anion during catalysis...