Piezo-Adapted 3-Isopropylmalate Dehydrogenase of the Obligate Piezophile Shewanella benthica DB21MT-2 Isolated from the 11,000-m Depth of the Mariana Trench

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3-Isopropylmalate dehydrogenase (IPMDH)-encoding leuB genes were obtained from the obligate piezophile Shewanella benthica DB21MT-2 and non-piezophile Shewanella oneidensis MR-1. The genes were expressed in Escherichia coli and the proteins were purified using His-tag. The estimated kinetic parameters of these enzymes indicated that IPMDH of S. benthica DB21MT-2 is more tolerant of high pressure than that of S. oneidensis MR-1. Thus such an adaptation is one of the mechanisms bacteria utilize for survival at high pressures.