Fig. 4

Characterization of MucF and its homologous proteins as deacylase. a LC–MS analysis of MucF and its homologous proteins in converting RTC to MUC. MUC was detected. b LC–MS analysis of MucF and its homologous proteins in converting RTC to MUC. RTC was detected. The cell lysate of E. coli Rosetta 2(DE3)pLysS/pET28a supplemented with RTC was used as the negative control for in vitro assays; E. coli BAP1::mucA-E (E. coli BAP1 containing pEXT06), which can produce RTC and does not contain MucF, was used as another negative control for in vivo assays. The function of MucF₃₅ was verified both in vitro and in vivo; MucF₁₄₀ represents MucF homologous proteins from non-MUC-producing S. mutans strains; MucF_Swi and MucF_Sgo were derived from Scardovia wiggsiae and S. gordonii respectively, representing MucF homologous proteins from oral bacteria other than S. mutans. See the LC–MS results of other MucF homologues in Additional file 1, Fig. S11, S12