Molecular characterization of cDNA encoding for adenylate kinase of rice (Oryza sativa L.).
Two types of genes (Adk-a, and Adk-b) encoding for adenylate kinase (AK, EC 2.7.4.3.) were isolated from the cDNA library constructed from poly(A)+ RNA of rice (Oryza sativa L.). Two cDNAs were heterogeneous at 5' and 3' ends of non-coding sequences and had possible polyadenylation signals. One of the genes, Adk-a, had 1154 bp sequences encoding 241 amino acid residues, while the other type, Adk-b, contained 1085 bp sequences encoding for 243 amino acid residues. Homology between Adk-a and Adk-b was 73.7% in nucleotide sequences, and 90.8% in amino acid level. Two genes showed about 53% homology to bovine mitochondrial adenylate kinase (AK2) at nucleotide and amino acid levels. Concerning the codon usage of rice AK genes, T was abundant at the third position of a codon in the reading frames. In order to examine the enzyme activity of the protein encoded by the rice cDNA, Adk-a was cloned into an expression vector, pUC119, which was introduced into Escherichia coli strain CV2, a temperature-sensitive mutant of adenylate kinase. We found that the transformant carrying the rice Adk-a gene in the sense orientation recovered cell growth at non-permissive high temperature (42 degrees C) and expressed enzyme activities higher than the untransformed CV2 and the transformant possessing Adk-a cDNA in the antisense orientation. These observations suggest that rice Adk-a codes a biologically active enzyme. Furthermore, sucrose was found to regulate the transcription of AK genes in rice cell cultures. Organ related accumulation of mRNA in whole plants was also found.
Kawai
M
M
Institute of Applied Microbiology, University of Tokyo, Japan.
Kidou
S
S
Kato
A
A
Uchimiya
H
H
D000263:Adenylate Kinase / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D005075:Biological Evolution; D003062:Codon / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D016366:Open Reading Frames / Q000235:genetics; D012275:Oryza / Q000201:enzymology / Q000235:genetics*; D010957:Plasmids / Q000235:genetics; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D003062:Codon; D011994:Recombinant Proteins; D000263:Adenylate Kinase