Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process...
Patent
1997-08-25
2000-12-05
Achutamurthy, Ponnathapu
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
435128, 435132, 435170, 435171, C12P 100
Patent
active
061565326
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of producing a fermentative product. In particular, the present invention relates to a method of fermentatively producing useful substances such as amino acids by utilizing microorganisms, and to microorganisms having added resistance to stress which would otherwise restrain growth of the microorganisms and/or production of the fermentative products.
BACKGROUND OF THE INVENTION
When cells are exposed to stress such as high temperature, high osmotic pressure, metabolic inhibition, presence of heavy metal, and viral infection, a family of proteins called "heat shock proteins" (hereinafter referred to as "HSP") are induced and synthesized in a short period of time to cause a defense reaction against the stress. HSP presents broad homology ranging from procaryotic cells to eucaryotic cells, and it is roughly divided into several groups (HSP 60 group, HSP 70 group, HSP 90 group, TRiC group, and miscellaneous group) (Hendrick, J. P. and Hartl, F. V., Annu. Rev. Biochem., 62, 349-384 (1993)).
The mechanism of stress resistance exhibited by HSP resides in the function of HSP to form higher-order structures of proteins (folding of proteins). Namely, when a protein is denatured due to stress, and becomes incapable of forming a correct higher-order structure, HSP binds to the protein, and the protein is subjected to refolding into the correct higher-order structure. Thus the protein can be returned to have its normal function.
HSP, which functions for the formation of higher-order structures of proteins as described above, has been revealed to serve as a molecular chaperon not only for denatured proteins but also for cells in a normal state through the process of protein folding, assembly, membrane transport and so on. Accordingly, its importance is recognized and widely noticed (Ellis, R. J. et al., Science, 250, 954-959 (1990)). The term "chaperon" means a supporter. This designation results from the fact that HSP binds to various proteins, and it exhibits its function.
Expression of HSP is induced when cells are exposed to stress as described above. The induction is usually temporary. It attenuates soon, and a new steady state is achieved. It has been revealed that the induction of HSP, is made at the transcription level (Cowing, D. C. et al., Proc. Natl. Acad. Sci. USA, 80, 2679-2683 (1985); Zhou, Y. N. et al., J. Bacteriol., 170, 3640-3649 (1988)). It is known that each of the family of HSP genes has a promoter structure called "heat shock promoter", and sigma-32 (.sigma..sup.=) is present which is a .sigma. (sigma) factor to specifically function for the heat shock promoter. It is known that .sigma..sup.= is a protein encoded by a rpoH gene, having an extremely short half-life of about 1 minute, and it closely relates to the temporary induction of HSP (Straus, D. B. et al., Nature, 329, 348-351 (1987)). It has been revealed that expression control for .sigma..sup.= itself is made at the transcription level and at the translation level, however, major control is made at the translation level.
The induction of HSP by heat shock is caused by two mechanisms of increase in synthetic amount of .sigma..sup.= and stabilization thereof. Among them, as for the increase in synthetic amount of .sigma..sup.=, it has been already revealed that the structure of .sigma..sup.= changes due to heat, and thus translation is accelerated (Yura, T. et al., Annu. Rev. Microbiol., 47, 321-350 (1993)). As for the stabilization of .sigma..sup.=, it has been shown that HSP (DnaK or the like) participates in degradation of .sigma..sup.=, assuming that feedback control by HSP functions (Tilly, K. et al., Cell, 34, 641-646 (1983); Liberek, K., Proc. Natl. Acad. Sci. USA, 89, 3516-3520 (1994)).
As for Escherichia coli (E. coli), it is known that the growth of cells relates to HSP in the presence of stress as described above (Meury, J. et al., FEMS Microbiol. Lett., 113, 93-100 (1993)). It is also known that production of human growth hormone is affected by dnaK, and secretion of pr
REFERENCES:
Goloubinoff P, et al. GroE heat-shock proteins promote assembly of foreign prokaryoticribulose bisphosphate carboxylase oligomers in Escherichia coli. Nature. Jan. 5, 1989; 337(6202): 44-47.
Van Dyk TK, et al. Demonstration by genetic suppression of interaction ofGroE products with many proteins. Nature. Nov. 23, 1989; 342(6248): 451-453.
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Tilly et al, "The DNAK Protein Modulates the Heat-Shock Response of Escherichia coli", Cell; vol. 34, 641-646, Sep. 1983.
Hockney, "Recent Developments in Heterologous Protein Production in Escherichia coli", TIBTECH, vol. 12, pp. 456-463, Nov. 1994.
Meury et al, "Impairment of Nucleoid Segregation and Cell Division at High Osmolarity in a Strain of Escherichia coli Overproducing the Chaperone DNAK", FEMS Microbiology Letters, vol. 113, 93-100, 1993.
Goto Shinya
Kawahara Yoshio
Kikuchi Yoshimi
Kimura Eiichiro
Kurahashi Osamu
Achutamurthy Ponnathapu
Ajinomoto Co. Inc.
Mayhew Bradley S.
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