Effect of amplification of desensitized purF and prs on inosine accumulation in Escherichia coli.
The effect of a phosphoribosylpyrophosphate (PRPP) synthetase gene (prs) that was desensitized to feedback inhibition by ADP on inosine accumulation was investigated using an inosine-producing mutant of Escherichia coli. At the same time, various types of plasmid having a PRPP amidotransferase gene (purF) that was desensitized to feedback inhibition by AMP and GMP were also investigated to improve inosine productivity using a compatible plasmid containing prs with a plasmid containing purF. The recombinant E. coli I-9 harboring a low-copy-number plasmid having the desensitized-purF (pMWKQ) accumulated 3.6 g/l inosine from 40 g/l glucose in a 2-d culture. Furthermore, desensitized-prs amplification, in addition to purF, resulted in the accumulation of 6.2 g/l inosine. Additionally, through these experiments, a spontaneous mutant with an enhanced inosine-producing ability compared with the parent strain I-9 was obtained. The spontaneous mutant I-9m harboring only pMWKQ and I-9m harboring both pMWKQ and pSTVDA (a plasmid having the desensitized-prs) accumulated 6.7 g/l and 7.5 g/l inosine, respectively, from 40 g/l glucose in a 3-d culture.
Shimaoka
Megumi
M
Fermentation and Biotechnology Laboratories, Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa 210-8681, Japan.
Takenaka
Yasuhiro
Y
Kurahashi
Osamu
O
Kawasaki
Hisashi
H
Matsui
Hiroshi
H
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000582:Amidophosphoribosyltransferase / Q000235:genetics* / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D005784:Gene Amplification; D018628:Gene Dosage; D005798:Genes, Bacterial; D007288:Inosine / Q000378:metabolism*; D009154:Mutation; D010957:Plasmids / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012268:Ribose-Phosphate Pyrophosphokinase / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*
D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; D007288:Inosine; D000244:Adenosine Diphosphate; D000582:Amidophosphoribosyltransferase; D012268:Ribose-Phosphate Pyrophosphokinase