Molecular cloning and characterization of a cDNA encoding soybean nodule IMP dehydrogenase

• Published in: Biochimica et biophysica acta 2001-09, Vol.1520 (3), p.242-246
• Main Authors: Cao, Yajuan, Schubert, Karel R
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Blotting, Northern; Blotting, Southern; cDNA cloning and characterization; Cloning, Molecular; DNA, Complementary - biosynthesis; DNA, Complementary - chemistry; Gene Library; Glycine max; Glycine max - enzymology; Glycine max - genetics; IMP Dehydrogenase - chemistry; IMP Dehydrogenase - genetics; Inosine monophosphate dehydrogenase; Isoelectric Point; Molecular Sequence Data; Molecular Weight; Nitrogen fixation; Nodule; Restriction Mapping; Sequence Alignment; Soybean; Ureide biogenesis
• ISSN: 0167-4781; 0006-3002; 1879-2634
• DOI: 10.1016/S0167-4781(01)00269-X

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 53 000 and a p I 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 ( ΔguaB) 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.