Transformant containing transaldolase gene

Abstract

The present invention relates to a novel transaldolase gene, and to a polypeptide encoded by the gene, a recombinant DNA obtained by ligating the gene, a transformant carrying the recombinant DNA, and a process for producing the polypeptide, aromatic amino acids, aromatic vitamins, L-histidine, riboflavin, nucleic acids, nucleic acid-associated substances, novel saccharides and others by utilizing the transformant.

Description

TECHNICAL FIELD [0001] The present invention relates to a novel transaldolase gene, and to a polypeptide encoded by the gene, a recombinant DNA obtained by ligating the gene, a transformant carrying the recombinant DNA, and a process for producing the polypeptide, aromatic amino acids, aromatic vitamins, L-histidine, riboflavin, nucleic acids, nucleic acid-associated substances, novel saccharides and others by utilizing the transformant. BACKGROUND ART [0002] Transaldolase is an enzyme involved in pentose phosphate pathways, and plays an important role in biosynthesis and metabolism of aromatic compounds such as aromatic amino acids and aromatic vitamins, nucleic acid-associated substances such as purine-nucleotide and pyrimidine-nucleotide, as well as L-histidine, riboflavin and others [Arch. Microbiol., 164, 324 (1995)]. Accordingly, a transaldolase gene and its gene products are useful as the target in breeding microorganisms for efficient fermentation and production of the metab...

AI Technical Summary

Benefits of technology

[0041] A DNA fragment containing the part that codes for the polypeptide and having a suitable length is prepared. If desired, the nucleotide sequence coding for the polypeptide of the present invention is partly substituted with other nucleotides so as to be a codon most suitable for expression of the resulting DNA in host cells. The DNA is useful in efficient production of the polypeptide of the present invention.

[0075] In case where the transformant of the present invention is prepared by the use of prokaryotic cells such as Escherichia coli or eukaryotic cells such as yeast as a host cell, the medium in which the transformant is cultured may be any natural or synthetic medium containing carbon sources, nitrogen sources and inorganic salts which can be assimilated by the transformant and in which the transformant can be efficiently cultured.

[0114] When using cells which can produce aromatic amino acids or aromatic vitamins as a host cell, their ability to produce the intended aromatic compounds can be increased, by increasing their transaldolase activity.

[0115] When using cells which can produce nucleic acid-associated substances such as purine-nucleotide and pyrimidine-nucleotide, L-histidine or riboflavin as a host cell, their ability to produce the substances can be increased, by lowering or deleting their transaldolase activity.

[0116] The transformant obtained in the manner as above is cultured in a medium to thereby produce and accumulate the intended product of aromatic amino acids, aromatic vitamins, L-histidine, riboflavin, purine-hucleotide, pyrimidine-nucleotide and other nucleic acid-associated substances, in the culture, and the product is isolated and purified from the culture according to known methods including concentration crystallization, activated charcoal treatment and ion-exchange resin treatment [Isao Endo et al's Bioseparation Process Handbook, edited by the Chemical Engineering Society of Japan, published by Kyoritsu Publishing (1996)]. Through the process, the intended substance can be obtained efficiently.

[0126] The method of the present invention makes it easy to produce saccharides which have heretofore been difficult to produce, and makes it possible to produce novel saccharides.

Problems solved by technology

However, for microorganisms belonging to the genus Corynebacterium that are widely used in amino acid fermentation of industrial importance, there is no report relating to the transaldolase gene and the enzyme encoded by the gene, and the nucleotide sequence of that gene is not known at all.