A small GTPase-like protein fragment of Mycoplasma promotes tumor cell migration and proliferation in vitro via interaction with Rac1 and Stat3

Abstract

The Mycoplasma genus comprises a group of microbes that cause persistent infection in humans and its role in promoting tumor development has long been a concern. Although mixtures of components isolated from Mycoplasma have been shown to activate host Rho family small GTPases and Stat3, no individual factor with this activity has been reported. In the current study, a conserved small GTPase-like protein fragment (SGLP) from Mycoplasma pulmonis chromosome partition protein, Smc, was identified as a virulence factor. SGLP was observed to interact with Rac1 and Stat3. The wild‑type (wt) SGLP, which contains a WxxxE motif, induced activation of Rac1 and phosphorylation of Stat3 at the tyrosine‑705 residue, while the SGLP mutant containing a mutation from WxxxE to AxxxA did not exert the same effects. Moreover, SGLP‑induced Stat3 phosphorylation was observed to be dependent upon Rac1 activity. Furthermore, wt SGLP was observed to promote cell migration and increase bromodeoxyuridine incorporation in HeLa cells and the SGLP mutant did not elicit these effects in HeLa cells. In conclusion, the current observations suggest that SGLP is an important virulence factor of Mycoplasma, which contributes to tumor cell migration and proliferation invitro via interaction with Rac1 and Stat3.