Solving Large Problems With Small Biofactories

Effect of different levels of aspartokinase on the lysine production by Corynebacterium lactofermentum.

Title

Effect of different levels of aspartokinase on the lysine production by Corynebacterium lactofermentum.

Publication Type
Journal Article
Year of Publication
1995
Journal
Appl Microbiol Biotechnol
Volume
43
Issue
1
Pagination
76-82
Date Published
1995 Apr
ISSN
0175-7598
Abstract

A 2.9-kb SacI fragment containing the ask-asd operon, encoding aspartokinase and aspartatesemialdehyde dehydrogenase, was cloned from an aminoethylcysteine-resistant, lysine-producing Corynebacterium lactofermentum strain. Enzymatic analysis showed that the aspartokinase (ASK) activity was completely resistant to inhibition by mixtures of lysine and threonine. Comparison of the deduced amino acid sequence of the beta submit of the ask gene showed three amino acid residue changes with ask gene encoding wild-type, feedback-sensitive enzymes. Three C. lactofermentum strains, one being aspartokinase-negative, one carrying two ask genes on the chromosome and one having a sixfold higher specific ASK activity than the parental strain, were constructed by transconjugation and electroporation, and used to analyse the role of ASK in the lysine production by C. lactofermentum. The results indicate that, in this study, feed-back-resistant ASK is necessary for high-level lysine production, but dispensable for lysine and diaminopimelate synthesis required for cell growth.

Alternate Journal
Appl Microbiol Biotechnol
Citation Key
205

PubMed ID

7766138

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