The 31-kDa polypeptide is an essential subunit of the vacuolar ATPase in Saccharomyces cerevisiae.
The VMA4 gene encodes a 26.6-kDa hydrophilic polypeptide which exhibits 34% sequence identity with the E subunit of the vacuolar ATPase from bovine kidney microsomes. The chromosomal VMA4 gene was inactivated by a 171-base pair deletion followed by insertion of the URA3 gene within the coding sequence. Null vma4 haploid mutants are viable. However, their growth is considerably slowed down specially in non-acidic conditions; they are cold sensitive and thermo-sensitive, exhibit poor growth on glycerol medium, and do not accumulate in their vacuole the red pigment of ade2 strains. No bafilomycin-sensitive ATPase is detected in a vacuolar fraction. These properties shared by null mutants in the A, B, and C subunits of the vacuolar ATPase show that the VMA4 polypeptide is also an essential component of the vacuolar ATPase which has been conserved from yeast to mammals. The tightly linked VMA4 and MIP1 (encoding the mitochondrial DNA polymerase) genes are divergently transcribed from face-to-face promoters. About 250 base pairs upstream of the VMA4 gene, Homoll and RPG consensus for the binding of TUF (RAP/GRF1) protein are present, suggesting that the VMA4 gene belongs to this large family of genes involved in cellular growth and division whose transcription is regulated by the TUF protein.
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Unité de Biochimie Physiologique, Université de Louvain, Louvain-la-Neuve, Belgium.
D000251:Adenosine Triphosphatases / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D005800:Genes, Fungal; D008040:Genetic Linkage; D007668:Kidney / Q000201:enzymology; D008969:Molecular Sequence Data; D009154:Mutation; D012333:RNA, Messenger / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D014158:Transcription, Genetic; D014617:Vacuoles / Q000201:enzymology*
D012333:RNA, Messenger; D000251:Adenosine Triphosphatases