PTS Galactitol Family

The PTS Galactitol (Gat) Family (TC# 4.A.5) is part of the PTS-AG superfamily. The biochemistry of this family is poorly defined. The only well-characterized member of this family is the galactitol permease of Escherichia coli.^[1] However, a homologous IIC protein from Listeria monocytogenes has been shown to be required for D-arabitol fermentation.^[2] It presumably functions together with IIA^Gat and IIB^Gat homologues. IIC^Gat is distantly related to IIC^Sgc of E. coli; IIA^Gat is distantly related to IIA^Sga and IIA^Sgcof E. coli as well as IIA^Mtl and IIA^Fru. IIB^Gat is distantly related to IIB^Sga and IIB^Sgc of E. coli.^[3] Domains in the LicR/CelR family of transcriptional activators show C-terminal domains exhibiting weak sequence similarity to IIB^Gat and IIA^Gat.^[4]