2.A.8 The Gluconate:H
Protein members of the GntP family include known gluconate permeases of E. coli and Bacillus species (Peekhaus et al., 1997; Reizer et al., 1991). Four of the seven E. coli paralogues have been found to possess active gluconate uptake activity, and one of them (GntW) can accommodate both L-idonate and D-gluconate although L-idonate is the physiological substrate (Bausch et al., 1998). Another (GntP) transports D-gluconate with high affinity but is specifically induced by and transports D-fructuronate (Bates Utz et al., 2004). GntT of E. coli is the physiological gluconate permease (Porco et al., 1997). These proteins are of about 450 residues and possess 12 or 14 putative transmembrane α-helical spanners. The GntP family is in the IT superfamily (Prakash et al., 2003).
The generalized transport reaction catalyzed by proteins of the GntP family is:
Carbohydrate acid (out) + nH