Electron Donor Systems to Facilitate Development of Assays for Two Flavoproteins Involved in Tetrahydromethanopterin Biosynthesis  

作　　者：Chao Pang Jose Moscaira Jenny Gong Madeline E. Rasche Chao Pang;Jose Moscaira;Jenny Gong;Madeline E. Rasche(Department of Chemistry and Biochemistry, California State University at Fullerton, Fullerton, CA, USA)

机构地区：[1]Department of Chemistry and Biochemistry, California State University at Fullerton, Fullerton, CA, USA

出　　处：《Advances in Microbiology》2020年第6期275-294,共20页微生物学（英文）

摘　　要：<span style="font-family:;" "=""><span style="font-family:Verdana;">Methane production by archaea depends on tetrahydromethanopterin (H</span>_{<span style="font-family:Verdana;">4</span>}<span style="font-family:Verdana;">MPT), a pterin-containing cofactor that carries one-carbon units. Two redox reactions within the nine steps of H</span>_{<span style="font-family:Verdana;">4</span>}<span style="font-family:Verdana;">MPT side chain biosynthesis have been hypothesized. Biochemical assays have demonstrated that the archaeal iron-sulfur flavoprotein dihydromethanopterin reductase X (DmrX or MM1854) catalyzes the final reaction of the pathway, the reduction of dihydromethanopterin to H</span>_{<span style="font-family:Verdana;">4</span>}<span style="font-family:Verdana;">MPT</span></span><span style="font-family:Verdana;">,</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> using dithiothreitol (DTT) as an artificial electron donor. The crystal structure of DmrB, a bacterial DmrX homolog that lacks iron-sulfur clusters, has led to a proposed ping-pong mechanism of electron transfer between FMNH</span>_{<span style="font-family:Verdana;">2</span>}<span style="font-family:Verdana;"> and the FMN prosthetic group of DmrB. However, an enzymatic assay to test the hypothetical DmrB mechanism is lacking because a suitable electron donor has not previously been identified. Furthermore, a second uncharacterized archaeal flavoprotein (MM1853) has been hypothesized to function in H</span>_{<span style="font-family:Verdana;">4</span>}<span style="font-family:Verdana;">MPT side chain biosynthesis. In this </span><span style="font-family:Verdana;">work, to facilitate the development of assays to elucidate the functions of DmrB </span><span style="font-family:Verdana;">and MM1853, we tested a variety of electron donors, including dithiothreitol, ferredoxin, and a system consisting of NADH and an NADH-dependent fla</span><span style="font-family:Verdana;">vin-reducing <span style="font-family:;" "=""><span style="font-family:Verdana;">Methane production by archaea depends on tetrahydromethanopterin (H</span>_{<span style="font-family:Verdana;">4</span>}<span style="font-family:Verdana;">MPT), a pterin-containing cofactor that carries one-carbon units. Two redox reactions within the nine steps of H</span>_{<span style="font-family:Verdana;">4</span>}<span style="font-family:Verdana;">MPT side chain biosynthesis have been hypothesized. Biochemical assays have demonstrated that the archaeal iron-sulfur flavoprotein dihydromethanopterin reductase X (DmrX or MM1854) catalyzes the final reaction of the pathway, the reduction of dihydromethanopterin to H</span>_{<span style="font-family:Verdana;">4</span>}<span style="font-family:Verdana;">MPT</span></span><span style="font-family:Verdana;">,</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> using dithiothreitol (DTT) as an artificial electron donor. The crystal structure of DmrB, a bacterial DmrX homolog that lacks iron-sulfur clusters, has led to a proposed ping-pong mechanism of electron transfer between FMNH</span>_{<span style="font-family:Verdana;">2</span>}<span style="font-family:Verdana;"> and the FMN prosthetic group of DmrB. However, an enzymatic assay to test the hypothetical DmrB mechanism is lacking because a suitable electron donor has not previously been identified. Furthermore, a second uncharacterized archaeal flavoprotein (MM1853) has been hypothesized to function in H</span>_{<span style="font-family:Verdana;">4</span>}<span style="font-family:Verdana;">MPT side chain biosynthesis. In this </span><span style="font-family:Verdana;">work, to facilitate the development of assays to elucidate the functions of DmrB </span><span style="font-family:Verdana;">and MM1853, we tested a variety of electron donors, including dithiothreitol, ferredoxin, and a system consisting of NADH and an NADH-dependent fla</span><span style="font-family:Verdana;">vin-reducing

关 键 词：Methanopterin Coenzyme Biosynthesis Dihydromethanopterin Reductase FLAVOPROTEIN ARCHAEA METHANOGENESIS 

分 类 号：Q78[生物学—分子生物学]