a catalytic role of xoxf1 as la3+-dependent methanol dehydrogenase in methylobacterium extorquens strain am1催化作用的xoxf1 la3 +端依赖甲醇脱氢酶在methylobacterium am1 extorquens压力.pdfVIP

A Catalytic Role of XoxF1 as La3+-Dependent Methanol Dehydrogenase in Methylobacterium extorquens Strain AM1 1 . 2. 3. 1 1 1 Tomoyuki Nakagawa * , Ryoji Mitsui , Akio Tani , Kentaro Sasa , Shinya Tashiro , Tomonori Iwama , Takashi Hayakawa1, Keiichi Kawai4 1 Faculty of Applied Biological Science, Gifu University, Gifu, Japan, 2 Department of Biochemistry, Faculty of Science, Okayama University of Science, Kita-ku, Okayama, Japan, 3 Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, Japan, 4 Tokai Gakuin University, Kakamigahara, Gifu, Japan Abstract In the methylotrophic bacterium Methylobacterium extorquens strain AM1, MxaF, a Ca2+-dependent methanol dehydrogenase (MDH), is the main enzyme catalyzing methanol oxidation during growth on methanol. The genome of strain AM1 contains another MDH gene homologue, xoxF1, whose function in methanol metabolism has remained unclear. In this work, we show that XoxF1 also functions as an MDH and is La3+-dependent. Despite the absence of Ca2+ in the medium strain AM1 was able to grow on methanol in the presence of La3+. Addition of La3+ increased MDH activity but the addition had no effect on mxaF or xoxF1 expression level. We purified MDH from strain AM1 grown on methanol in the presence of La3+, and its N-terminal amino acid sequence corresponded to that of XoxF1. The enzyme contained La3+ as a cofactor. The DmxaF mutant strain could not grow on methanol in the presence of Ca2+, but was able to grow after supplementation with La3+. Taken together, these results show that XoxF1 participates in methanol metabolism as a La3+- dependent MD