Relationship between the Glutamate Production and the Activity of 2-Oxoglutarate Dehydrogenase in<i>Brevibacterium lactofermentum</i>

Kawahara, Yoshio; Takahashi-Fuke, Keiko; Shimizu, Eihan; Nakamatsu, Tsuyoshi; Nakamori, Shigeru

doi:10.1271/bbb.61.1109

Cited by 102 publications

(53 citation statements)

References 5 publications

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“…A significant decrease in ODHC activity is observed under L-glutamate-producing conditions (8), suggesting that its attenuation is a prerequisite for L-glutamate production by C. glutamicum. However, it has been observed that some odhA disruptants often produce little, if any, L-glutamate.…”

Section: Resultsmentioning

confidence: 95%

“…The activity of the 2-oxoglutarate dehydrogenase complex (ODHC) reportedly decreases during L-glutamate production in response to biotin limitation, fatty acid ester surfactants, and penicillin (8). Since ODHC is located at the branch point between the tricarboxylic acid (TCA) cycle and L-glutamate biosynthesis, a decrease in ODHC activity could switch the metabolic flow from the TCA cycle to L-glutamate synthesis.…”

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confidence: 99%

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Mutations of the Corynebacterium glutamicum NCgl1221 Gene, Encoding a Mechanosensitive Channel Homolog, Induce l -Glutamic Acid Production

Nakamura

Hirano

Ito

et al. 2007

Appl Environ Microbiol

181

161

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Corynebacterium glutamicum is a biotin auxotroph that secretes L-glutamic acid in response to biotin limitation; this process is employed in industrial L-glutamic acid production. Fatty acid ester surfactants and penicillin also induce L-glutamic acid secretion, even in the presence of biotin. However, the mechanism of L-glutamic acid secretion remains unclear. It was recently reported that disruption of odhA, encoding a subunit of the 2-oxoglutarate dehydrogenase complex, resulted in L-glutamic acid secretion without induction. In this study, we analyzed odhA disruptants and found that those which exhibited constitutive L-glutamic acid secretion carried additional mutations in the NCgl1221 gene, which encodes a mechanosensitive channel homolog. These NCgl1221 gene mutations lead to constitutive L-glutamic acid secretion even in the absence of odhA disruption and also render cells resistant to an L-glutamic acid analog, 4-fluoroglutamic acid. Disruption of the NCgl1221 gene essentially abolishes L-glutamic acid secretion, causing an increase in the intracellular L-glutamic acid pool under biotin-limiting conditions, while amplification of the wild-type NCgl1221 gene increased L-glutamate secretion, although only in response to induction. These results suggest that the NCgl1221 gene encodes an L-glutamic acid exporter. We propose that treatments that induce L-glutamic acid secretion alter membrane tension and trigger a structural transformation of the NCgl1221 protein, enabling it to export L-glutamic acid.L-Glutamate has a distinctive taste, known as "umami," that is neither sweet, sour, salty, nor bitter (24), and it is widely used as a flavor enhancer. About 1.8 million tons of monosodium glutamate are produced worldwide per year by fermentation using coryneform bacteria. These are rod-shaped, nonsporulating, gram-positive bacteria containing mycolic acids and are widely distributed in the natural world. A nonpathogenic species, Corynebacterium glutamicum, was originally isolated as an L-glutamate-producing bacterium (12, 34). Wild-type C. glutamicum, without breeding, releases more than 80 g/liter of L-glutamic acid under appropriate culture conditions (27).The mechanism of L-glutamate secretion by C. glutamicum is unique. The presence of biotin, which is required by C. glutamicum for growth, inhibits L-glutamate production in the culture medium, while production is induced under biotinlimiting conditions (26) and in response to fatty acid ester surfactants (31) and penicillin (22). It is also induced by ethambutol treatment, which inhibits formation of the mycolic acid layer of the cell wall (25). Since biotin limitation and the other inducing treatments cause damage to cell surface structures of this microorganism, it has long been assumed that L-glutamate leaks through the cell membrane (32).The dtsR1 gene, isolated as a multicopy suppressor of a mutant hypersensitive to fatty acid ester surfactants, encodes a protein showing strong homology to the ␤ subunit of acetylcoenzyme A (CoA) carboxylase (10). Sinc...

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Section: Resultsmentioning

confidence: 95%

mentioning

confidence: 99%

Mutations of the Corynebacterium glutamicum NCgl1221 Gene, Encoding a Mechanosensitive Channel Homolog, Induce l -Glutamic Acid Production

Nakamura

Hirano

Ito

et al. 2007

Appl Environ Microbiol

181

161

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“…Under L-glutamate producing conditions, 2-oxoglutarate dehydrogenase complex (ODHC) activity decreases, causing a change in metabolic flux from the TCA cycle to L-glutamate synthesis. [33][34][35][36] GOF mutants of NCgl1221 produced L-glutamate without any inducing treatment. 18,37) This means that NCgl1221 itself switches metabolic flux to synthesize L-glutamate when the channel is open in response to inducing treatment as well as by mutation.…”

Section: Discussionmentioning

confidence: 99%

L-Glutamate Secretion by the N-Terminal Domain of theCorynebacterium glutamicumNCgl1221 Mechanosensitive Channel

Yamashita

Hashimoto

Kumagai

et al. 2013

Bioscience, Biotechnology, and Biochemistry

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“…Biochemical analysis of C. glutamicum has revealed that 2-oxoglutarate dehydrogenase (ODH) activity was significantly reduced during glutamate overproduction, 5,6) causing an increase in carbon flux for glutamate synthesis at the ODH branch point. 7) Furthermore, the activity of pyruvate dehydrogenase decreased and the activity of pyruvate carboxylase increased (except when the biotin supply was limited), suggesting that a metabolic change occurs at the pyruvate node.…”

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confidence: 99%

The Protein Encoded byNCgl1221inCorynebacterium glutamicumFunctions as a Mechanosensitive Channel

Hashimoto¹,

Nakamura²,

Kuroda³

et al. 2010

Bioscience, Biotechnology, and Biochemistry

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The function of the NCgl1221-encoded protein of Corynebacterium glutamicum was analyzed using Bacillus subtilis as host because a method for preparing the giant provacuole required for electrophysiological studies has been established. Expression of NCgl1221 in a strain deficient in mscL and ykuT, both of which encode mechanosensitive channels, resulted in an 8.9-fold higher cell survival rate upon osmotic downshock than the control. Electrophysiological investigation showed that the giant provacuole prepared from this strain, expressing NCgl1221, exhibited significantly higher pressuredependent conductance than the control. These findings show that the NCgl1221-encoded protein functions as a mechanosensitive channel.

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Relationship between the Glutamate Production and the Activity of 2-Oxoglutarate Dehydrogenase inBrevibacterium lactofermentum

Cited by 102 publications

References 5 publications

Mutations of the Corynebacterium glutamicum NCgl1221 Gene, Encoding a Mechanosensitive Channel Homolog, Induce l -Glutamic Acid Production

Mutations of the Corynebacterium glutamicum NCgl1221 Gene, Encoding a Mechanosensitive Channel Homolog, Induce l -Glutamic Acid Production

L-Glutamate Secretion by the N-Terminal Domain of theCorynebacterium glutamicumNCgl1221 Mechanosensitive Channel

The Protein Encoded byNCgl1221inCorynebacterium glutamicumFunctions as a Mechanosensitive Channel

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