The Drosophila Na,K-ATPase alpha-subunit gene: gene structure, promoter function and analysis of a cold-sensitive recessive-lethal mutation

Genes Funct. 1997 Apr;1(2):99-117. doi: 10.1046/j.1365-4624.1997.00006.x.

Abstract

The Drosophila Na,K-ATPase (or sodium pump) alpha-subunit gene was found to contain 10 exons and span approx. 25 kb. Two nearly adjacent transcriptional initiation sites were identified, and the 2085-nucleotide sequence upstream of the first transcriptional start was analysed for promoter activity in transfected Drosophila SL2 cells. This region was found to contain many cis-acting elements that influence promoter activity, including elements that confer 2- to 3-fold higher activity in SL2 cells cultured at 30 degrees C versus 22 degrees C. Temperature-sensitive transcriptional regulation of the Na,K-ATPase alpha-subunit in Drosophila is a plausible mechanistic candidate for the factor driving temperature-dependent up-regulation of the Na,K-ATPase alpha-subunit described here for fly strains homozygous for single P-element insertions in the alpha-subunit gene. Four new P-element insertion strains were identified in this study, each insertion site lying within the first intron of the Na,K-ATPase alpha-subunit gene. The insertion in strain 0462 resulted in cold-sensitive recessive lethality; flies homozygous for the 0462 mutation could be rescued by growth at 29-30 degrees C, a condition that partially corrected a deficiency in the level of Na,K-ATPase alpha-subunit. The high-temperature rescue of homozygous 0462 flies appeared to result primarily from improved Na,K-ATPase expression rather than an increase in the rate of ion transport per Na,K-ATPase molecule. These observations point to a role for sodium-pump activity in determining the range of temperature tolerance in Drosophila and demonstrate that relatively subtle changes in sodium-pump expression can have major consequences in whole organisms.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adaptation, Physiological
  • Animals
  • Base Sequence
  • Cell Line
  • DNA
  • DNA Footprinting
  • DNA Transposable Elements
  • Drosophila / enzymology
  • Drosophila / genetics*
  • Drosophila / physiology
  • Exons
  • Genes, Lethal*
  • Genes, Recessive*
  • Heterozygote
  • Homozygote
  • Introns
  • Molecular Sequence Data
  • Mutation*
  • Promoter Regions, Genetic*
  • Protein Binding
  • Sodium-Potassium-Exchanging ATPase / genetics*
  • Sodium-Potassium-Exchanging ATPase / metabolism
  • Temperature
  • Transcription, Genetic

Substances

  • DNA Transposable Elements
  • DNA
  • Sodium-Potassium-Exchanging ATPase