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首页> 外文期刊>Journal of bacteriology >CDP-2,3-Di-O-Geranylgeranyl-sn-Glycerol:l-Serine O-Archaetidyltransferase (Archaetidylserine Synthase) in the Methanogenic Archaeon Methanothermobacter thermautotrophicus
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CDP-2,3-Di-O-Geranylgeranyl-sn-Glycerol:l-Serine O-Archaetidyltransferase (Archaetidylserine Synthase) in the Methanogenic Archaeon Methanothermobacter thermautotrophicus

机译：CDP-2,3-二-O-Geranylgeranyl-sn-甘油：1-丝氨酸O-Archaetidyltransferase（Archaetidylserine Synthase）在产甲烷古细菌中甲烷甲烷嗜热菌的自养

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CDP-2,3-di-O-geranylgeranyl-sn-glycerol:l-serine O-archaetidyltransferase (archaetidylserine synthase) activity in cell extracts of Methanothermobacter thermautotrophicus cells was characterized. The enzyme catalyzed the formation of unsaturated archaetidylserine from CDP-unsaturated archaeol and l-serine. The identity of the reaction products was confirmed by thin-layer chromatography, fast atom bombardment-mass spectrum analysis, and chemical degradation. The enzyme showed maximal activity in the presence of 10 mM Mn2+ and 1% Triton X-100. Among various synthetic substrate analogs, both enantiomers of CDP-unsaturated archaeols with ether-linked geranylgeranyl chains and CDP-saturated archaeol with ether-linked phytanyl chains were similarly active toward the archaetidylserine synthase. The activity on the ester analog of the substrate was two to three times higher than that on the corresponding ether-type substrate. The activity of d-serine with the enzyme was 30% of that observed for l-serine. A trace amount of an acid-labile, unsaturated archaetidylserine intermediate was detected in the cells by a pulse-labeling experiment. A gene (MT1027) in M. thermautotrophicus genome annotated as the gene encoding phosphatidylserine synthase was found to be homologous to Bacillus subtilis pssA but not to Escherichia coli pssA. The substrate specificity of phosphatidylserine synthase from B. subtilis was quite similar to that observed for the M. thermautotrophicus archaetidylserine synthase, while the E. coli enzyme had a strong preference for CDP-1,2-diacyl-sn-glycerol. It was concluded that M. thermautotrophicus archaetidylserine synthase belongs to subclass II phosphatidylserine synthase (B. subtilis type) on the basis of not only homology but also substrate specificity and some enzymatic properties. The possibility that a gene encoding the subclass II phosphatidylserine synthase might be transferred from a bacterium to an ancestor of methanogens is discussed.
机译：CDP-2,3-di -O-香叶基香叶基- sn -甘油：1-丝氨酸 O -古菌基转移酶（古菌基丝氨酸合酶）的活性鉴定了嗜热甲烷单栖嗜热菌细胞的提取物。该酶催化从CDP-不饱和古生酚和L-丝氨酸形成不饱和古魏基丝氨酸。通过薄层色谱法，快速原子轰击质谱分析和化学降解来确认反应产物的身份。在10 mM Mn 2 + 和1％Triton X-100的存在下，该酶表现出最大的活性。在各种合成的底物类似物中，具有醚连接的香叶基香叶基链的CDP-不饱和古生酚和具有醚连接的植烷链的CDP-饱和古生酚的对映异构体对古菌基丝氨酸合酶具有相似的活性。对底物的酯类似物的活性比相应的醚型底物的活性高两到三倍。 d-丝氨酸的酶活性是l-丝氨酸的30％。通过脉冲标记实验，在细胞中检测到痕量的酸不稳定的不饱和古生物碱丝氨酸中间体。 M中的一个基因（MT1027）。发现标注为编码磷脂酰丝氨酸合酶基因的嗜热自养菌基因组与枯草芽孢杆菌pssA同源，而与大肠杆菌pssA同源。磷脂酰丝氨酸合酶的底物特异性 B。枯草杆菌与 M观察到的非常相似。 Thermautotrophicus 古菌基丝氨酸合酶，而 E。大肠杆菌酶对CDP-1,2-二酰基- sn -甘油具有强烈的偏好。结论是 M。嗜热栖腐菌古菌基丝氨酸合酶属于II类磷脂酰丝氨酸合酶（ B.subtilis 型），不仅具有同源性，而且具有底物特异性和一些酶特性。讨论了编码II类磷脂酰丝氨酸合酶的基因可能从细菌转移到产甲烷菌的祖先的可能性。

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