Molecular cloning and characterization of a cDNA encoding soybean nodule IMP dehydrogenase.
Inosine monophosphate dehydrogenase (IMPDH) catalyzes the rate-limiting step in de novo purine biosynthesis and is a postulated key enzyme in nitrogen assimilation in ureide-exporting nodules. A 2016 bp cDNA for IMPDH, designated as IMPDH, was cloned from a soybean nodule cDNA library. IMPDH encodes a polypeptide of 502 amino acids with a predicted molecular weight of 53000 and a pI of 5.54. The deduced IMPDH is 70.5% identical to that in Arabidopsis, with a 100% homology in the putative active-site region. Expressing the cloned cDNA in Escherichia coli mutant strain KLC381 (DeltaguaB) restored IMPDH activity, permitting bacterial growth on minimal medium. Southern blot analysis suggested a single copy of IMPDH gene in the soybean genome. Northern blot analysis showed that the expression of IMPDH gene is apparently nodule-specific.
Cao
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Y
Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019-0245, USA. yajuancao@yahoo.com
Schubert
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KR
D000595:Amino Acid Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000096:biosynthesis / Q000737:chemistry; D015723:Gene Library; D007168:IMP Dehydrogenase / Q000737:chemistry / Q000235:genetics*; D007526:Isoelectric Point; D008969:Molecular Sequence Data; D008970:Molecular Weight; D015183:Restriction Mapping; D016415:Sequence Alignment; D013025:Glycine max / Q000201:enzymology / Q000235:genetics*
D018076:DNA, Complementary; D007168:IMP Dehydrogenase