The SzA mutations of the B subunit of the Drosophila vacuolar H+ ATPase identify conserved residues essential for function in fly and yeast

Du, J., Kean, L., Allan, A.K., Southall, T.D., Davies, S.A. , McInerny, C.J. and Dow, J.A.T. (2006) The SzA mutations of the B subunit of the Drosophila vacuolar H+ ATPase identify conserved residues essential for function in fly and yeast. Journal of Cell Science, 119(12), pp. 2542-2551. (doi:10.1242/jcs.02983)

Full text not currently available from Enlighten.

Abstract

V-ATPases play multiple roles in eukaryotes: in Drosophila, null mutations are recessive lethal. Here, mutations underlying five extant lethal alleles of vha55, encoding the B subunit, were identified, including a premature termination codon and two mutations very close to residues thought to participate in the catalytic site of the enzyme. Lethality of these alleles could be reverted by transformation of flies with a wild type vha55::GFP fusion, confirming that the lethal phenotype described for these alleles was due to defects in V-ATPase function. The chimeric protein was correctly localised to the apical domain of the Malpighian (renal) tubule, and restored fluid transport function to wild-type levels. No dominant-negative phenotype was apparent in heterozygotes. When the vha55::GFP fusion was driven ubiquitously, fluorescent protein was only detectable in tissues known to contain high levels of V-ATPase, suggesting that vha55 requires stoichometric co-expression of other subunits to be stable. Yeast (Saccharomyces cerevisiae) deleted for the corresponding gene (Deltavma2) demonstrated a pH-sensitive growth phenotype that was rescued by the vha55::GFP construct. Deltavma2 yeast could not be rescued with fly cDNAs encoding any of the mutant vha55 alleles, confirming the functional significance of the mutated residues. In yeast, bafilomycin-sensitive ATPase activity and growth rate correlated with the ability of different constructs to rescue the pH-sensitive conditional-lethal phenotype. These classical Drosophila mutants thus identify residues that are essential for function in organisms with wide phylogenetic separation.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:McInerny, Dr Christopher and Dow, Professor Julian and Davies, Professor Shireen
Authors: Du, J., Kean, L., Allan, A.K., Southall, T.D., Davies, S.A., McInerny, C.J., and Dow, J.A.T.
College/School:College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
College of Medical Veterinary and Life Sciences > School of Life Sciences
Journal Name:Journal of Cell Science
Journal Abbr.:J. Cell Sci.
ISSN:0021-9533
ISSN (Online):1477-9137
Published Online:30 May 2006

University Staff: Request a correction | Enlighten Editors: Update this record

Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
343251Comparative integrative physiology of novel branches of the NA+/H+ exchanger familyJulian DowBiotechnology and Biological Sciences Research Council (BBSRC)S19561Institute of Molecular Cell and Systems Biology