4.A.5 The PTS Galactitol (Gat) Family

The only well-characterized member of the Gat famly is the galactitol permease of E. coli (Noblemann and Lengeler, 1995). However, a homologous IIC protein (38% identity) from Listeria monocytogenes has been shown to be required for D-arabitol fermentation (Saklani-Jusforgues et al., 2001). It presumably functions together with IIA^Gat and IIB^Gat homologues. IIC^Gat is distantly related to IIC^Sgc of E. coli (Reizer et al., 1996); IIA^Gat is distantly related to IIA^Sga and IIA^Sgc of E. coli as well as IIA^Mtl and IIA^Fru. IIB^Gat is distantly related to IIB^Sga and IIB^Sgc of E. coli. Domains in the LicR/CelR family of transcriptional activators show C-terminal domains exhibiting weak sequence similiarity to IIB^Gat and IIA^Gat (Tchieu et al., 2001). The biochemistry of this family is poorly defined.