Membrane-bound sorbitol dehydrogenase is responsible for the unique oxidation of D-galactitol to L-xylo-3-hexulose and D-tagatose in Gluconobacter oxydans
Membrane-bound sorbitol dehydrogenase is responsible for the unique oxidation of D-galactitol to L-xylo-3-hexulose and D-tagatose in Gluconobacter oxydans
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膜结合山梨糖醇脱氢酶负责氧化葡萄糖杆菌中 D-半乳糖醇独特氧化为 L-木糖-3-己酮糖和 D-塔格糖
DOI：
10.1016/j.bbagen.2022.130289
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Hairong Cheng
中科院分区：
文献类型：
--
作者：
Yirong Xu;Liyun Ji;Shuo Xu;Muhammad Bilal;Armin Ehrenreich;Zixin Deng;Hairong Cheng
Background: Gluconobacter oxydans, is used in biotechnology because of its ability to oxidize a wide variety of.carbohydrates, alcohols, and polyols in a stereo- and regio-selective manner by membrane-bound dehydrogenases located in periplasmic space. These reactions obey the well-known Bertrand-Hudson’s rule. In our.previous study (BBA-General Subjects, 2021, 1865:129740), we discovered that Gluconobacter species,.including G. oxydans and G. cerinus strain can regio-selectively oxidize the C-3 and C-5 hydroxyl groups of Dgalactitol to rare sugars D-tagatose and L-xylo-3-hexulose, which represents an exception to Bertrand Hudson’s.rule. The enzyme catalyzing this reaction is located in periplasmic space or membrane-bound and is PQQ.(pyrroloquinoline quinine) and Ca2+-dependent; we were encouraged to determine which type of enzyme(s).catalyze this unique reaction..Methods: Enzyme was identified by complementation of multi-deletion strain of Gluconobacter oxydans 621H with.all putative membrane-bound dehydrogenase genes..Results and conclusions: In this study, we identified this gene encoding the membrane-bound PQQ-dependent.dehydrogenase that catalyzes the unique galactitol oxidation reaction in its 3’-OH and 5’-OH. Complement.experiments in multi-deletion G. oxydans BP.9 strains established that the enzyme mSLDH (encoded by.GOX0855–0854, sldB-sldA) is responsible for galactitol’s unique oxidation reaction. Additionally, we demonstrated that the small subunit SldB of mSLDH was membrane-bound and served as an anchor protein by fusing it.to a red fluorescent protein (mRubby), and heterologously expressed in E. coli and the yeast Yarrowia lipolytica..The SldB subunit was required to maintain the holo-enzymatic activity that catalyzes the conversion of Dgalactitol to L-xylo-3-hexulose and D-tagatose. The large subunit SldA encoded by GOX0854 was also characterized, and it was discovered that its 24 amino acids signal peptide is required for the dehydrogenation activity.of the mSLDH protein..General significance: In this study, the main membrane-bound polyol dehydrogenase mSLDH in G. oxydans 621H.was proved to catalyze the unique galactitol oxidation, which represents an exception to the Bertrand Hudson’s.rule, and broadens its substrate ranges of mSLDH. Further deciphering the explicit enzymatic mechanism will.prove this theory.
