Investigation of phosphorylation status of OdhI protein during penicillin- and Tween 40-triggered glutamate overproduction by <Emphasis Type="Italic">Corynebacterium glutamicum</Emphasis> |
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Authors: | Jongpill?Kim Email author" target="_blank">Takashi?HirasawaEmail author Masaki?Saito Chikara?Furusawa Email author" target="_blank">Hiroshi?ShimizuEmail author |
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Institution: | (1) Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan;(2) Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan; |
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Abstract: | Glutamate overproduction by Corynebacterium glutamicum is triggered by treatment with penicillin or Tween 40 and is accompanied by a decrease in 2-oxoglutarate dehydrogenase complex
(ODHC) activity. We have reported that de novo synthesis of OdhI, which inhibits ODHC activity by interacting specifically
with the E1o subunit of ODHC (OdhA), is induced by penicillin, and that odhI overexpression induces glutamate overproduction in the absence of any triggers for glutamate overproduction. In this study,
to determine the function of OdhI in glutamate overproduction by C. glutamicum, changes in OdhI levels and phosphorylation status during penicillin- and Tween 40-induced glutamate overproduction were
examined by western blot. The synthesis of both unphosphorylated and phosphorylated OdhI was increased by addition of Tween
40 or penicillin and the levels of unphosphorylated OdhI, which can inhibit ODHC activity, was significantly higher than those
of phosphorylated OdhI, which is unable to inhibit ODHC activity. Meanwhile, the OdhA levels were maintained throughout the
culture. These results indicate that OdhI synthesis is induced by additions of penicillin and Tween 40 and most synthesized
OdhI is unphosphorylated, resulting in the decrease in ODHC activity and glutamate overproduction. Similarly, in the odhI-overexpressing strain, both unphosphorylated and phosphorylated OdhI were synthesized, while the levels of OdhA were nearly
constant throughout culture. Our results suggest that high level of unphosphorylated OdhI regulates glutamate overproduction
by C. glutamicum. |
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