Several distinct genes encode nearly identical 16 kDa proteolipids of the vacuolar H+-ATPase from Arabidopsis thaliana

Imara Y. Perera, Xuhang Li, Heven Sze

Research output: Contribution to journalArticle

Abstract

To understand the subcellular roles and the regulation of vacuolar H+-ATPases, we have begun to identify the genes encoding the major subunits and to determine their patterns of expression in Arabidopsis thaliana. Two distinct cDNAs (AVA-P1 and AVA-P2) and one genomic sequence (AVA-P3) encoding the 16 kDa subunit have been isolated. The 16 kDa proteolipid is a major component of the membrane integral sector that forms the proton conductance pathway and is required for assembly of the V-ATPase complex. Interestingly, the open reading frame of one full-length cDNA (AVA-P1) and a genomic sequence (AVA-P3) encoded an identical polypeptide of 164 amino acids with a molecular mass of 16570. The deduced amino acid sequences of the two cDNAs were nearly identical (99%) and hydropathy plots suggested a molecule with four membrane-spanning domains characteristic of V-ATPase proteolipids. The three genes differed mainly in their codon usage and in their 3′-untranslated regions. The coding region of the genomic sequence, AVA-P3, was interrupted by two introns located at the codons for Cys-26 and Arg-121. The presence of additional 16 kDa proteolipid genes was suggested from several polymerase chain reaction (PCR)-amplified fragments that differed from one another in the size of the second intron. PCR 1 had an intron of ca. 800 bp and its identity as AVA-P4, a fourth member of the gene family, was confirmed from sequence analyses of an EST cDNA. The mRNAs of three genes (AVA-P1, AVA-P2 and AVA-P3) were detected in Arabidopsis leaf, root, flower and silique; yet expression of AVA-P1 and AVA-P2 was lower in roots. All three genes were expressed in light- or dark-grown seedlings; however mRNA levels of AVA-P2 were enhanced in etiolated plants. Arabidopsis thaliana, there-fore, has at least four distinct genes encoding nearly identical 16 kDa proteolipids, and the enhanced expression of AVA-P2 transcript in etiolated seedlings suggests that an increase in V-ATPase could accompany cell expansion.

Original languageEnglish (US)
Pages (from-to)227-244
Number of pages18
JournalPlant Molecular Biology
Volume29
Issue number2
DOIs
StatePublished - Oct 1 1995
Externally publishedYes

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Keywords

  • 16 kDa subunit
  • Arabidopsis thaliana
  • H-pumping ATPase
  • multigene family
  • proteolipid
  • vacuolar-type

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Genetics
  • Plant Science

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