title: Identification of conserved polar residues important for salt tolerance by the Na+/H+ exchanger of Schizosaccharomyces pombe.
abstract: 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.
authors.affiliation: Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7. lfliegel@ualberta.ca
authors.forename: Larry
authors.initials: L
authors.lastname: Fliegel
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics* / Q000502:physiology; D001692:Biological Transport / Q000235:genetics / Q000502:physiology; D009997:Osmotic Pressure; D017354:Point Mutation / Q000235:genetics* / Q000502:physiology; D012568:Schizosaccharomyces / Q000235:genetics* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics* / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics* / Q000378:metabolism
chemical_list: D029702:Schizosaccharomyces pombe Proteins; D017923:Sodium-Hydrogen Exchangers
references.citation: Biochim Biophys Acta. 1996 Jan 12;1278(1):111-8
references.pmid: 8611597
references.citation: Biochim Biophys Acta. 1994 Mar 23;1190(2):465-8
references.pmid: 8142450
references.citation: Cell. 1989 Jan 27;56(2):271-80
references.pmid: 2536298
references.citation: Proc Natl Acad Sci U S A. 1988 Jun;85(12):4148-52
references.pmid: 3288985
references.citation: Biochemistry. 2002 Jan 15;41(2):609-17
references.pmid: 11781101
references.citation: Biochim Biophys Acta. 2001 May 1;1505(1):144-57
references.pmid: 11248196
references.citation: FEBS Lett. 1997 Mar 17;405(1):119-24
references.pmid: 9094438
references.citation: J Biol Chem. 1998 Aug 14;273(33):21054-60
references.pmid: 9694857
references.citation: J Biochem. 1994 Nov;116(5):1030-8
references.pmid: 7896730
references.citation: Biochim Biophys Acta. 1995 Jun 30;1230(3):170-6
references.pmid: 7619834
references.citation: Proc Natl Acad Sci U S A. 1989 Dec;86(23):9228-32
references.pmid: 2556706
references.citation: FEBS Lett. 1995 Apr 24;363(3):264-8
references.pmid: 7737413
references.citation: J Biol Chem. 1993 Jun 5;268(16):11925-8
references.pmid: 7685026
references.citation: FEMS Microbiol Lett. 2002 Mar 19;209(1):39-43
references.pmid: 12007651
references.citation: Yeast. 1995 Jul;11(9):829-38
references.pmid: 7483847
references.citation: Biochemistry. 1998 Jun 9;37(23):8282-8
references.pmid: 9622480
references.citation: EMBO J. 1992 Apr;11(4):1631-40
references.pmid: 1314171
references.citation: J Biol Chem. 1996 Jun 7;271(23):13385-91
references.pmid: 8662775
references.citation: Eur J Biochem. 2001 Sep;268(17):4674-85
references.pmid: 11532004
references.citation: J Biol Chem. 2000 Mar 17;275(11):7942-9
references.pmid: 10713111
references.citation: Comput Appl Biosci. 1994 Dec;10(6):685-6
references.pmid: 7704669
references.citation: Biochem J. 2001 Jul 1;357(Pt 1):1-10
references.pmid: 11415429
references.citation: J Biol Chem. 1992 May 5;267(13):9331-9
references.pmid: 1577762
references.citation: FEBS Lett. 1996 May 27;387(1):89-93
references.pmid: 8654575
references.citation: J Biol Chem. 1990 Apr 15;265(11):6262-7
references.pmid: 2138616
references.citation: Biochem Biophys Res Commun. 1991 Aug 15;178(3):1176-81
references.pmid: 1872836
references.citation: J Biochem. 2002 Jun;131(6):821-31
references.pmid: 12038978
references.citation: Biochem J. 2004 Apr 1;379(Pt 1):31-8
references.pmid: 14680478
references.citation: J Biol Chem. 1997 Oct 17;272(42):26145-52
references.pmid: 9334180
references.citation: Methods Enzymol. 1991;194:795-823
references.pmid: 2005825
references.citation: Curr Opin Cell Biol. 2000 Aug;12(4):431-4
references.pmid: 10873827
references.citation: Genes Dev. 1998 May 15;12 (10 ):1453-63
references.pmid: 9585505
references.citation: J Biochem. 1997 Apr;121(4):661-70
references.pmid: 9163515
references.citation: Mol Cell Biochem. 2003 Dec;254(1-2):117-24
references.pmid: 14674689
references.citation: FEBS Lett. 1998 Mar 6;424(1-2):1-5
references.pmid: 9537504