2.A.8 The Gluconate:H+ Symporter (GntP) Family

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+ (out) → Carbohydrate acid (in) + nH+ (in).

This family belongs to the IT Superfamily.



Anfora, A.T., and R.A. Welch. (2006). DsdX is the second D-serine transporter in uropathogenic Escherichia coli clinical isolate CFT073. J. Bacteriol. 188: 6622-6628.

Bates Utz, C., A.B. Nguyen, D.J. Smalley, A.B. Anderson, and T. Conway. (2004). GntP is the Escherichia coli fructuronic acid transporter and belongs to the UxuR regulon. J. Bacteriol. 186: 7690-7696.

Bausch, C., N. Peekhaus, C. Utz, T. Blais, E. Murray, T. Lowary, and T. Conway. (1998). Sequence analysis of the GntII (subsidiary) system for gluconate metabolism reveals a novel pathway for L-idonic acid catabolism in Escherichia coli. J. Bacteriol. 180: 3704-3710.

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Letek, M., N. Valbuena, A. Ramos, E. Ordóñez, J.A. Gil, and L.M. Mateos. (2006). Characterization and use of catabolite-repressed promoters from gluconate genes in Corynebacterium glutamicum. J. Bacteriol. 188: 409-423.

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Porco, A., E.E. Gamero, E. Mylonás, and T. Istúriz. (2008). Gluconate as suitable potential reduction supplier in Corynebacterium glutamicum: cloning and expression of gntP and gntK in Escherichia coli. Biol Res 41: 349-358.

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Prakash, S., G. Cooper, S. Singhi, and M.H. Saier, Jr. (2003). The ion transporter superfamily. Biochim. Biophys. Acta 1618: 79-92.

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Yang, M., T. Mu, W. Zhong, A.M. Olajuyin, and J. Xing. (2017). Analysis of gluconate metabolism for pyruvate production in engineered Escherichia coli based on genome-wide transcriptomes. Lett Appl Microbiol 65: 165-172.


TC#NameOrganismal TypeExample

D-Gluconate:H+ symporter of 448 aas and 11 TMSs.  It is encoded in an operon with gluconate kinase (Fujita et al. 1986).


GntP of Bacillus subtilis


D-glycerate transporter of 430 aas and 14 putative TMSs.  The gene is next to and probably in the same operon with a gene encoding D-glycerate kinase.


D-glycerate transporter of Enterococcus faecium


Putative gluconate analog transporter of 449 aas and 11 TMSs, YjhF.

YjhF of E. coli


The putative histidine porter, YuiF. Regulated by Histidine repressor HisR (Ravcheev et al. 2011)

Proteobacteria, Firmicutes

YuiF of Bacillus subtilis (O32105)


A putative propionate/butyrate/hydroxybutyrate transporter


Putative propionate permease of Fusobacterium nucleatum (gi 19704150)


Putative D-beta-hydroxy butyrate permease, BhbP


BhbP of Bacillus cereus (Q81E21)


Gluconate porter of 463 aas and 13 TMSs, GntP (Letek et al. 2006; Porco et al. 2008).

GntP of Corynebacterium glutamicum (Brevibacterium saccharolyticum)


L-Idonate/D-Gluconate:H+ symporter, IdnT, GntW, YjgT, of 439 aas and 11 or 12 TMSs. Also called the GNT-II system (Bausch et al., 1998; Gómez et al. 2011).


IdnT (GntW; YjgT) of E. coli

2.A.8.1.3D-Fructuronate/D-gluconate:H+ symporter, GntP (Bates Utz et al., 2004)BacteriaGntP of E. coli (P0AC94)

High affinity D-Gluconate:H+ symporter, GntT (GntM, UsgA, YhgC) of 438 aas and 11 or 12 TMSs (Porco et al., 1997). It is regulated at the transcriptional level by GntR and Crp (Peekhaus and Conway 1998).


GntT of E. coli (P39835)


The D-serine transporter, DsdX (KM=60µM) (may also transport D-threonine which inhibits D-serine uptake) (Anfora and Welch, 2006). Eliminating the dsdX gene renders the cell more sensitive to chloramphenicol (Duo et al. 2008).


DsdX of E. coli (P08555)


The putative D-glycerate transporter, GrtP. Regulated by glycerate-responsive regulator SdaR (Rodionov et al. 2011)


GrtP of Shewanella oneidensis (Q8EG39)


Inner membrane uptake permease, YgbN, of 454 aas and 14 TMSs. Multi-ion irradiation caused the generation of a ygbN mutant (Song and Luo 2012).


YgbN of Escherichia coli


Low-affinity (212 μM), gluconate-inducible, gluconate transporter (gluconate permease) (GntU/the Gnt-I system) (Tong et al. 1996). The gntU gene is in an operon with gntK, encoding a gluconate kinase (Tong et al. 1996).  This system has been utilized for the production of pyruvate from gluconate (Yang et al. 2017).


GntU of Escherichia coli

2.A.8.1.9Uncharacterized transporter HI_0092BacteriaHI_0092 of Haemophilus influenzae

TC#NameOrganismal TypeExample