The arabinose kinase, ARA1, gene of Arabidopsis is a novel member of the galactose kinase gene family.
The arabinose-sensitive ara1-1 mutant of Arabidopsis is deficient in arabinose kinase activity. A candidate for the ARA1 gene. ISA1, has been previously identified through the Arabidopsis genome sequencing initiative. Here we demonstrate that (1) the ARA1 gene coincides with ISA1 in a positional cloning strategy; (2) there are mutations in the ISA1 gene in both the ara1-1 mutant and an intragenic suppressor mutant; and (3) the ara1-1 and suppressor mutant phenotypes can be complemented by the expression of the ISA1 cDNA in transgenic plants. Together these observations confirm that ISA1 is the ARA1 gene. ARA1 is a member of the galactose kinase family of genes and represents a new substrate specificity among this and other families of sugar kinases. A second gene with similarities to members of the galactose kinase gene family has been identified in the EST database. A 1.8 kb cDNA contained an open reading-frame predicted to encode a 496 amino acid polypeptide. The GAL1 cDNA was expressed in a galK mutant of Escherichia coli and in vitro assays of extracts of the strain expressing GAL1 confirmed that the cDNA encodes a galactose kinase activity. Both GAL1 and ARA1 cross-hybridise at low stringency to other sequences suggesting the presence of additional members of the galactose kinase gene family.
Sherson
S
S
Department of Genetics, University of Melbourne, Parkville, Australia.
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I
Medd
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J
Schmidt
R
R
Dean
C
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Kreis
M
M
Lecharny
A
A
Cobbett
C
C
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins; D016386:Chromosome Walking; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D005686:Galactokinase / Q000235:genetics*; D017343:Genes, Plant / Q000235:genetics*; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics*; D020161:Physical Chromosome Mapping; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D018076:DNA, Complementary; D018744:DNA, Plant; D017853:Phosphotransferases (Alcohol Group Acceptor); C111816:ARA1 protein, Arabidopsis; D005686:Galactokinase