CDP-2,3-di-O-geranylgeranyl-sn-glycerol:L-serine O-archaetidyltransferase (archaetidylserine synthase) in the methanogenic archaeon Methanothermobacter thermautotrophicus
CDP-2,3-di-O-geranylgeranyl-sn-glycerol:L-serine O-archaetidyltransferase (archaetidylserine synthase) in the methanogenic archaeon Methanothermobacter thermautotrophicus
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DOI：
10.1128/jb.185.4.1181-1189.2003
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发表时间：
2003-02-01
影响因子：
3.2
通讯作者：
Koga, Y
中科院分区：
文献类型：
--
作者：
Morii, H;Koga, Y
CDP-2，3-二-O-香叶基香叶基-sn-甘油：表征了甲烷热杆菌热自养型细胞的细胞提取物中的L-丝氨酸O-古细菌酰转移酶（古细菌酰丝氨酸合酶）活性。该酶催化CDP-不饱和古菌醇和L-丝氨酸形成不饱和古菌酰丝氨酸。通过薄层色谱、快速原子轰击-质谱分析和化学降解确认了反应产物的身份。该酶在10 mM Mn 2+和1% Triton X-100存在下显示出最大活性。在各种合成底物类似物中，具有醚连接的香叶基香叶基链的CDP-不饱和古菌和具有醚连接的植烷基链的CDP-饱和古菌的两种对映异构体对古菌酰丝氨酸合酶具有类似的活性。对底物的酯类似物的活性比对相应的醚类底物的活性高2 ~ 3倍。D-丝氨酸与酶的活性是L-丝氨酸所观察到的活性的30%。微量的酸不稳定的，不饱和的archeotidylserine中间体中检测到的细胞中的脉冲标记实验。在M.被注释为编码磷脂酰丝氨酸合成酶的热营养菌基因组被发现与枯草杆菌pssA同源，但与大肠杆菌pssA不同源。B磷脂酰丝氨酸合成酶的底物特异性。subtilis与M. thermautotrophicus archaetidylserine synthase，而E.大肠杆菌酶对CDP-1，2-二酰基-sn-甘油有很强的选择性。结果表明，M.嗜热自养菌古菌酰丝氨酸合酶属于II类磷脂酰丝氨酸合酶（B. subtilis型）的基础上，不仅同源性，而且底物特异性和一些酶的性质。编码亚类II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进行了讨论。
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.