Protein-L-Isoaspartyl Methyltransferase (PIMT) Is Required for Survival of Salmonella Typhimurium at 42°C and Contributes to the Virulence in Poultry

Poultry birds are asymptomatic reservoir of Typhimurium ( . Typhimurium) but act as source of human infection for this bacterium. Inside the poultry, . Typhimurium experiences several stresses, 42°C body temperature of birds is one of them. Proteins are highly susceptible to temperature mediated damage. Conversion of protein bound aspartate (Asp) residues to iso-aspartate (iso-Asp) is one of such modifications that occur at elevated temperature. Iso-Asp formation has been linked to protein inactivation and compromised cellular survival. Protein-L-isoaspartyl methyltransferase (PIMT) can repair iso-Asp back to Asp, thus enhances the cellular survival at elevated temperature. Here, we show that the gene deletion strain of . Typhimurium (Δ mutant strain) is hypersensitive to 42°C . The hypersusceptibility of Δ strain is partially reversed by plasmid based complementation ( -complementation) of Δ strain. Following oral inoculation, Δ strain showed defective colonization in poultry caecum, and compromised dissemination to spleen and liver. Interestingly, we have observed three and half folds induction of the PIMT protein following exposure of . Typhimurium to 42°C. Our data suggest a novel role of gene in the survival of . Typhimurium at elevated temperature and virulence.