Sunday, July 26, 2009
P115

Search for transporters involved in C4-dicarboxylates utilization in Corynebacterium glutamicum

Haruhiko Teramoto, Tomokazu Shirai, Masayuki Inui, and Hideaki Yukawa. Molecular Microbiology and Biotechnology Group, Research Institute of Innovative Technology for the Earth (RITE), 9-2, Kizugawadai, Kizugawa, Kyoto, Japan

Corynebacterium glutamicum, a high-GC Gram-positive bacterium, is widely used for the industrial production of amino acids. We have developed a bioprocess for production of lactate, succinate, and ethanol using C. glutamicum. It is important to understand the mechanism of chemical transport across the cellular membrane for the improvement of the bioprocess. In this study, we searched for a transporter involved in C4-dicarboxlylates utilization in C. glutamicum, and found that, on the C. glutamicum R genome, eight genes encode proteins with sequence similarity to the functionally characterized C4-dicarboxylate transporters in other bacteria. These proteins are classified into DAACS, TRAP-T, or DASS family. A mutant strain deficient in one of these genes, designated dcsT, of the DASS family did not grow on C4-dicarboxylates, succinate, fumarate and malate, as sole carbon sources. A mutant strain deficient in each of the other seven genes grew as well on these substrates as the wild type strain. The utilization of C4-dicarboxylates was markedly enhanced by overexpression of the dcsT gene. The uptake of 13C-labeled succinate observed for the wild type strain was barely detected in the dcsT-deficient mutant, but was markedly enhanced in a dcsT-overexpressing strain. These results suggested that in C. glutamicum, the uptake of C4-dicarboxylates is mainly mediated by the DASS transporter encoded by dcsT.
This work was partially supported by a grant from the New Energy and Industrial Technology Development Organization (NEDO).

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