Characterisation of the enzyme activities involved in the valine biosynthetic pathway in a valine-producing strain of Corynebacterium glutamicum

Leyval, Damien; Uy, Davin; Delaunay, Stéphane; Goergen, Jean‐Louis; Engasser, Jean‐Marc

doi:10.1016/s0168-1656(03)00162-7

Cited by 85 publications

(112 citation statements)

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“…Mutant studies further identified the genes (and respective enzymes) bioA (adenosylmethionine-8-amino-7-oxononanoate aminotransferase) (10), argD (N-acetyl-ornithine AT) (29), and pat and pdxR (involved in aromatic amino acid and pyridoxal-5Ј-phosphate synthesis, respectively) (19). Furthermore, an activity has been identified that uses L-alanine as the amino donor (17), thus resembling AvtA of E. coli (37). The function of some of these ATs was derived from a recent bioinformatic approach identifying a total of 20 sequences with similarities to ATs in the genome of C. glutamicum (19).…”

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Functional Analysis of All Aminotransferase Proteins Inferred from the Genome Sequence ofCorynebacterium glutamicum

et al. 2005

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Twenty putative aminotransferase (AT) proteins of Corynebacterium glutamicum, or rather pyridoxal-5-phosphate (PLP)-dependent enzymes, were isolated and assayed among others with L-glutamate, L-aspartate, and L-alanine as amino donors and a number of 2-oxo-acids as amino acceptors. One outstanding AT identified is AlaT, which has a broad amino donor specificity utilizing (in the order of preference) L-glutamate > 2-aminobutyrate > L-aspartate with pyruvate as acceptor. Another AT is AvtA, which utilizes L-alanine to aminate 2-oxo-isovalerate, the L-valine precursor, and 2-oxo-butyrate. A second AT active with the L-valine precursor and that of the other two branched-chain amino acids, too, is IlvE, and both enzyme activities overlap partially in vivo, as demonstrated by the analysis of deletion mutants. Also identified was AroT, the aromatic AT, and this and IlvE were shown to have comparable activities with phenylpyruvate, thus demonstrating the relevance of both ATs for L-phenylalanine synthesis. We also assessed the activity of two PLPcontaining cysteine desulfurases, supplying a persulfide intermediate. One of them is SufS, which assists in the sulfur transfer pathway for the Fe-S cluster assembly. Together with the identification of further ATs and the additional analysis of deletion mutants, this results in an overview of the ATs within an organism that may not have been achieved thus far.

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Functional Analysis of All Aminotransferase Proteins Inferred from the Genome Sequence ofCorynebacterium glutamicum

et al. 2005

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“…Biochemical characterization of C. glutamicum AHAS has been reported, 6) and the affinity of AHAS for pyruvate has been found to be weak (K m ¼ 8:3 mM). The intracellular concentration of pyruvate was estimated to be between 1.6 mM and 5 mM in C. glutamicum under glutamate-producing conditions.…”

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“…The activity of the ilvB promoter has been reported to be increased about 2 times under valine-, isoleucine-, and leucine-limited conditions. 6,29) Constitutive expression of ilvBNC might also improve valine productivity. In addition, valine production using a pyruvate dehydrogenase knockout mutant of C. glutamicum was reported recently.…”

Section: Discussionmentioning

confidence: 99%

“…14) AHAS activity was determined spectro- photometrically, as described previously. 6) The specific activities of these enzymes were expressed as nmol acetoin produced min À1 (mg protein) À1 .…”

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“…1): acetohydroxyacid synthase (AHAS, ilvBN gene products), acetohydroxyacid isomeroreductase (AHAIR, ilvC gene product), dihydroxy acid dehydratase (DHAD, ilvD gene product), and transaminase B (ilvE gene product). 6) AHAS is a key enzyme due to its feedback inhibition by the branched-chain amino acids. Elišáková et al reported that introduction of a feedback-insensitive AHAS gene into C. glutamicum caused increased valine production.…”

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Enhanced Valine Production inCorynebacterium glutamicumwith Defective H⁺-ATPase and C-Terminal Truncated Acetohydroxyacid Synthase

Wada

Hijikata

Aoki

et al. 2008

Bioscience, Biotechnology, and Biochemistry

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Amino Acids, Branched Chain,L‐Isoleucine

Jojima

Inui

Yukawa

2010

Encyclopedia of Industrial Biotechnology

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This article is an overview of the biosynthetic pathway of L ‐isoleucine and its regulation in Escherichia coli , and also describes evolution of L ‐isoleucine‐hyperproducing strains of microorganisms. L ‐isoleucine is one of three branched‐chain amino acids (BCAAs). They are synthesized de novo by bacteria, fungi and plants, but are nutritionally essential for vertebrates. The importance of L ‐isoleucine in nutrition has stimulated intensive researches for development of microorganisms capable of overproducing L ‐isoleucine for industrial production by fermentation from sugar. BCAAs are synthesized via parallel biosynthetic pathways. Four enzymes, acetohydroxyacid synthase (AHAS), acetohydroxyacid isomeroreductase (AHAIR), dihydroxy acid dehydrase (DH), and transaminase B (TrB), are shared in both L ‐isoleucine and L ‐valine synthesis. The first enzyme AHAS catalyzes the condensation of pyruvate and 2‐ketobutyrate for L ‐isoleucine synthesis or the condensation of two molecules of pyruvate for L ‐valine synthesis. Biosynthesis of L ‐isoleucine as well as other BCAAs is tightly controlled by complex regulation mechanisms that include multivalent regulation of both gene expression and feed back inhibition of enzyme activities by end product BCAAs. A variety of microbial strains with high productivity of L ‐isoleucine have been developed by screening mutants that can grow in the presence of BCAA analogs and by genetic engineering. In these mutants, the regulation of L ‐isoleucine synthesis including repression of gene expression and feed back inhibition are released. This article also describes a novel bioprocess, living cell reaction (LCR) process, that has potential to address the disadvantages of existing fermentation processes including low yield and by‐product formation.

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Characterisation of the enzyme activities involved in the valine biosynthetic pathway in a valine-producing strain of Corynebacterium glutamicum

Cited by 85 publications

References 54 publications

Functional Analysis of All Aminotransferase Proteins Inferred from the Genome Sequence ofCorynebacterium glutamicum

Functional Analysis of All Aminotransferase Proteins Inferred from the Genome Sequence ofCorynebacterium glutamicum

Enhanced Valine Production inCorynebacterium glutamicumwith Defective H⁺-ATPase and C-Terminal Truncated Acetohydroxyacid Synthase

Amino Acids, Branched Chain,L‐Isoleucine

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Characterisation of the enzyme activities involved in the valine biosynthetic pathway in a valine-producing strain of Corynebacterium glutamicum

Cited by 85 publications

References 54 publications

Functional Analysis of All Aminotransferase Proteins Inferred from the Genome Sequence ofCorynebacterium glutamicum

Functional Analysis of All Aminotransferase Proteins Inferred from the Genome Sequence ofCorynebacterium glutamicum

Enhanced Valine Production inCorynebacterium glutamicumwith Defective H+-ATPase and C-Terminal Truncated Acetohydroxyacid Synthase

Amino Acids, Branched Chain,L‐Isoleucine

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Enhanced Valine Production inCorynebacterium glutamicumwith Defective H⁺-ATPase and C-Terminal Truncated Acetohydroxyacid Synthase