4.A.4 The PTS Glucitol (Gut) Family

The Gut family consists only of glucitol-specific porters, but these occur both in Gram-negative and Gram-positive bacteria. IIGut of E. coli consists of three proteins, a IIA protein, a putative 4 TMS IIC2 protein and a putative 4 TMS IIC1 protein (Nguyen et al., 2006). The N- and C-termini as well as the IIB domain may thereby be localized to the cell cytoplasm, but the topology has not been established experimentally. IIAGut is believed to be phosphorylated on a histidyl residue, while IIBGut is probably phosphorylated on a cysteyl residue. However, these possibilities have not been demonstrated experimentally.

This family belongs to the PTS-GFL Superfamily.



Nguyen, T.X., M.R. Yen, R.D. Barabote, and M.H. Saier, Jr. (2006). Topological predictions for integral membrane permeases of the phosphoenolpyruvate:sugar phosphotransferase system. J. Mol. Microbiol. Biotechnol. 11: 345-360.

Reizer, J., W.J. Mitchell, N. Minton, J. Brehm, A. Reizer, and M.H. Saier, Jr. (1996). Proposed topology of the glucitol permeases of Escherichia coli and Clostridium acetobutylicum. Curr. Microbiol. 33: 331-333.

Tangney, M., J.K. Brehm, N.P. Minton, and W.J. Mitchell. (1998). A gene system for glucitol transport and metabolism in Clostridium beijerinckii NCIMB 8052. Appl. Environ. Microbiol. 64: 1612-1619.

Testa, C.A., R.M. Cornish, and C.D. Poulter. (2004). The sorbitol phosphotransferase system is responsible for transport of 2-Cmethyl-D-erythritol into Salmonella enterica serovar typhimurium. J. Bacteriol. 186: 473-480.

Yamada, M. and M.H. Saier, Jr. (1987). Glucitol-specific enzymes of the phosphotransferase system in Escherichia coli: Nucleotide sequence of the gut operon. J. Biol. Chem. 262: 5455-5463.


TC#NameOrganismal TypeExample
4.A.4.1.1Glucitol porter (also transports 2-C-methyl-D-erythritol, an isoprenoid biosynthetic precursor; Testa et al., 2004)Bacteria and phosphorylates Glucitol IIBC1-IIC2-IIA complex of E. coli

The Glucitol Enzyme II complex, IICBC (GutA1A2) IIA (GutB) 


GutA1A2B of Clostridium beijerinckii 
GutA1 (O32332)
GutA2 (O32333)
GutB (O32334)