Читать книгу Plant Nucleotide Metabolism - Hiroshi Ashihara - Страница 56

GAR is metabolised by the enzyme glycineamide ribonucleotide transformylase (GARFT, EC 2.1.2.2) using 10-formyltetrahydrofolate (10-Formyl-THF) to generate formylglycineamide ribonucleotide (FGAR) (step 3, Figure 4.1, Reaction 3).

Soybean nodule cDNA clones pur2 and pur3 encode enzymes that catalyse the second and the third steps of the de novo purine biosynthesis pathway, namely, GARS and GARFT, which were isolated by complementation of corresponding E. coli mutants. One class of the cDNA clone of GARS and the clones of three classes of GARFT cDNA were identified. These pur2 and pur3 genes are highly expressed in young and mature nodules but weakly expressed in roots and leaves. Expression levels of the mRNAs of these two genes were not enhanced even when ammonia was provided to non-nodulated roots. (Schnorr et al. 1996).