Transcriptional regulon controlled by tyrosine phosphatases in Porphyromonas gingivalis
Tyrosine phosphorylation/dephosphorylation posttranslational modification (PTM) of proteins in bacteria can control their function and location.  While PTM of transcriptional regulators and DNA-binding proteins impacts gene transcription, little is known regarding the transcriptional landscape regulating tyrosine phospho-relay circuitry.  In this study, we performed RNA-Seq of Porphyromonas gingivalis strains with mutations in ltp1 and php1 genes encoding the two major tyrosine phosphatases, a low molecular weight family enzyme and a histidinol phosphate phosphoesterase family enzyme, respectively.  Additionally, strains were tested in both in vitro and in vivo (mouse abscess) conditions.  Both the ?ltp1 and the ?php1 mutants exhibit little transcriptional difference to the parental strain cultured in vitro, which would tend to exclude a significant role of the phosphatases in P. gingivalis gene regulation under nutrient-rich, low-stress conditions.  While the ?php1 mutant also clustered closely to the parental strain in the abscess condition, there were a number of differentially regulated genes (DEGs) associated with transporter systems.  In the mouse abscess condition, DEGs in ?ltp1 included one of the efflux ABC transporter systems also regulated in the ?php1 mutant.  However, the primary biological process populated by DGEs in ?ltp1 involved genome stability.   Comparison of the parental strain between the in vitro and in vivo condition indicated that DNA metabolic processes, including recombination and transposition, were significantly upregulated in vivo.  Hence, Ltp1 specifically may be involved in the control of adaptation to in vivo conditions, while Ltp1 and Php1 have both common and enzyme-specific activities. Overall design: We investigated the role that the bacterial tyrosine phosphatases Ltp1 and Ptk1 have on the transcriptome of Porphyromonas gingivalis during mouse infection and during in vitro culture conditions. This was performed by either inoculating mice with either the parental wildtype (WT) ATCC 33277 strain or isogenic deletion mutants lacking either Ltp1 (?ltp1) or Php1 (?php1) then collecting abscess material, or inoculating standard TSB media supplemented with hemin and menadinone then collecting washed cell pellets and subjecting both sets of samples to RNASeq.