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2.A.62 The NhaD Na+:H+ Antiporter (NhaD) Family

The NhaD Na+/H+ antiporter has been characterized from two Vibrio species: V. parahaemolyticus and V. cholerae (Nozaki et al., 1998; Ostroumov et al., 2002) and in the haloalkaliphile, Alkalimonas amylolytica (Liu et al., 2005). These proteins and their homologues are 400-500 aas long and exhibit 10-13 TMSs. They catalyze Na+/H+ and Li+/H+ antiport. They exhibit activity at basic pH (8-10) with no activity at pH 7.5. The Amylolytica antiporter has low Na+ affinity and has optimal activity at 600 mM Na+. Homologues are found in proteobacteria of all groups, Flavobacteria and Chlamydia. Distant homologues of the IT superfamily are ubiquitous. The NhaD family is a constituent of the IT superfamily (Prakash et al., 2003).

The generalized reaction catalyzed by NhaD is:

nH+ (in) + mNa+ (out) ⇌ nH+ (out) + mNa+ (in).

(n and m are unknown, but are probably 1 or 2)

 

This family belongs to the: IT Superfamily.

References associated with 2.A.62 family:

Barrero-Gil, J., A. Rodríguez-Navarro, and B. Benito. (2007). Cloning of the PpNHAD1 transporter of Physcomitrella patens, a chloroplast transporter highly conserved in photosynthetic eukaryotic organisms. J Exp Bot 58: 2839-2849. 17617660
Cui, Y., B. Cheng, Y. Meng, C. Li, H. Yin, P. Xu, and C. Yang. (2016). Expression and functional analysis of two NhaD type antiporters from the halotolerant and alkaliphilic Halomonas sp. Y2. Extremophiles 20: 631-639. 27315164
Kurz, M., A.N. Brünig, and E.A. Galinski. (2006). NhaD type sodium/proton-antiporter of Halomonas elongata: a salt stress response mechanism in marine habitats? Saline Systems 2: 10. 16872527
Liu, J., Y. Xue, Q. Wang, Y. Wei, T.H. Swartz, D.B. Hicks, M. Ito, Y. Ma, and T.A. Krulwich. (2005). The activity profile of the NhaD-type Na+(Li+)/H+ antiporter from the Soda Lake haloalkaliphile Alkalimonas amylolytica is adaptive for the extreme environment. J. Bacteriol. 187: 7589-7595. 16267283
Melo, A.M., N.A. Felix, J.N. Carita, L.M. Saraiva, and M. Teixeira. (2006). The Na+/H+ antiporter of the thermohalophilic bacterium Rhodothermus marinus. Biochem. Biophys. Res. Commun. 348: 1011-1017. 16904646
Nozaki, K., T. Kuroda, T. Mizushima, and T. Tsuchiya. (1998). A new Na+/H+ antiporter, NhaD, of Vibrio parahaemolyticus. Biochim. Biophys. Acta 1369: 213-220. 9518619
Ostroumov, E., J. Dzioba, P. Loewen, and P. Dibrov. (2002). Asp344 and Thr345 are critical for cation exchange mediated by NhaD, Na+/H+ antiporter of Vibrio cholerae. Biochim. Biophys. Acta 1564: 99-106. 12101001
Prakash, S., G. Cooper, S. Singhi, and M.H. Saier, Jr. (2003). The ion transporter superfamily. Biochim. Biophys. Acta 1618: 79-92. 14643936
Zhong, N.Q., L.B. Han, X.M. Wu, L.L. Wang, F. Wang, Y.H. Ma, and G.X. Xia. (2012). Ectopic expression of a bacterium NhaD-type Na+/H+ antiporter leads to increased tolerance to combined salt/alkali stresses. J Integr Plant Biol 54: 412-421. 22583823