Fig. 3

Engineering strategy for guanosine production. A deletion of the gene purA was combined with overexpression of the genes prs, purF, and guaB under the control of the strong P₄₃ promoter. The gene abbreviations are as follows: purA encodes adenylosuccinate synthase; prs encodes ribose-phosphate pyrophosphokinase; purF encodes amidophosphoribosyltransferase; guaB encodes IMP dehydrogenase