Transcriptional Regulon Controlled by Tyrosine Phosphatases in Porphyromonas gingivalis

Tyrosine phosphorylation/dephosphorylation post-translational modification (PTM) of proteins in bacteria can control their function and location. PTM of transcriptional regulators and DNA-binding proteins, as well as components of their signaling pathways, can impact gene expression. However, little is known regarding the global impact of tyrosine phosphatases on the bacterial transcriptome. In this study, we performed RNA-Seq of Porphyromonas gingivalis wild type (WT) along with strains Δltp1 and Δphp1 with mutations in the genes encoding the two major tyrosine phosphatases, Ltp1 and Php1, respectively. Moreover, these strains were tested in vitro and in vivo (mouse abscess) conditions. Both the Δltp1 and the Δphp1 mutants exhibited little transcriptional difference to the parental strain when cultured in vitro. In vivo, comparison of the Δphp1 mutant to the WT showed a number of differentially regulated genes (DEGs) associated with transporter systems. In vivo DEGs in Δltp1 included one of the efflux ABC transporter systems also regulated in the Δphp1 mutant; however, the primary biological process populated by DEGs in Δltp1 involved genome stability. Comparison of the WT strain between the in vitro and in vivo condition indicated that DNA metabolic processes, including recombination and transposition, were significantly upregulated in vivo. Hence, a major role of Ltp1 phosphatase activity at the transcriptional level may be control of adaptation to in vivo conditions. Additionally, both Ltp1 and Php1 have common functions in the control of the expression of genes encoding transporter systems.