Molecular and Cellular Biochemistry

, Volume 268, Issue 1–2, pp 83–92

Identification of conserved polar residues important for salt tolerance by the Na+/H+ exchanger of Schizosaccharomyces pombe



The Na+/H+ exchanger is a ubiquitous protein that transports Na+ and H+ in opposite directions across cell membranes. In fission yeast, the Na+/H+ exchanger sod2 plays a major role in the removal of excess detrimental intracellular sodium. The effect of mutagenesis of conserved polar amino acids of sod2 was examined by expressing 10 different mutant forms of sod2 in sod2 deficient S. pombe and characterizing salt tolerance. Asp145, 266, 267, and Glu173 were critical for proper function of sod2. Asp241 had an intermediate effect on sod2 function while mutation of Asp178 did not impair sod2 function. Simultaneous mutation of the Asp266, 267 pair impaired sod2 function. Mutation of each individual residue demonstrated that both were critical for sod2 function. Conservative mutations (Asp to Glu) of Asp266 and 267 failed to restore sod2 function. The results suggest that acidic residues associated with transmembrane segments are important in function, possibly being important in binding and coordinating cations. (Mol Cell Biochem 268: 83–92, 2005)

Key words

Na+/H+ exchanger Schizosaccharomyces pombe, cation binding salt tolerance 


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Copyright information

© Kluwer Academic Publishers 2005

Authors and Affiliations

  1. 1.Department of Biochemistry, 347 Medical Science BuildingUniversity of AlbertaEdmontonCanada

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