Biotin biosynthetic pathway in recombinant strains of Escherichia coli overexpressing bio genes: evidence for a limiting step upstream from KAPA

Autor: Fabienne Soubrier, Francis Blanche, Sophie Levy-Schil, Fabrice Bacchetta, Sylvie Rigault, Laurent Debussche, Delphine Lagneaux, Josiane Schleuniger, Joel Crouzet, Jean-François Mayaux
Rok vydání: 1993
Předmět:
Zdroj: Applied Microbiology and Biotechnology. 38:755-762
ISSN: 1432-0614
0175-7598
DOI: 10.1007/bf00167141
Popis: The effect of the overexpression of the bioABFCD operon on the biotin biosynthetic pathway was investigated in an Escherichia coli K12 bioR mutant with a chromosomal deletion for the biotin operon. When transformed with a multicopy number plasmid containing bioABFCD, this strain synthetized 10,000 times more biotin than a wild-type E. coli strain. In order to further increase biotin production, the bioA and bioB operons were subcloned into plasmids with stronger promoters and in some cases optimal ribosome binding sites. The new constructions led to the accumulation of large amounts of soluble Bio proteins (although not BioC) but did not improve biotin production. In all the constructed strains, BioA, BioD, and BioB activities were greatly amplified but these activitie did not correlate with the level of protein syntthesis. These strains accumulated only low levels of vitamers, auggesting that the major limiting step for higher biotin production occurs upstream from the first intermediate of the Bio pathway we assayed (7,keto-8-aminopelargonic acid). As BioC overproduction was shown to impair cell growth, we could not determine if this early step of pathway was limiting.
Databáze: OpenAIRE
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