N-EPSILON-ACETYL-BETA-LYSINE - AN OSMOLYTE SYNTHESIZED BY METHANOGENIC ARCHAEBACTERIA
N-EPSILON-ACETYL-BETA-LYSINE - AN OSMOLYTE SYNTHESIZED BY METHANOGENIC ARCHAEBACTERIA
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DOI：
10.1073/pnas.87.23.9083
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发表时间：
1990-12-01
影响因子：
11.1
通讯作者：
ROBERTS, MF
中科院分区：
文献类型：
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作者：
SOWERS, KR;ROBERTSON, DE;ROBERTS, MF
嗜热甲烷八叠球菌是一种非海洋产甲烷古细菌，可以在一系列盐水浓度中生长。当氯化钠浓度低于 0.4 M 时，嗜热菌会积累谷氨酸以应对渗透压的增加。在大于0.4mM NaCl时，该生物体合成了修饰的β-氨基酸，通过NMR波谱法和离子交换HPLC将其鉴定为N.ε-乙酰基-β-赖氨酸。这种β-氨基酸衍生物在嗜热菌和另一种被检测的产甲烷菌中积累到高细胞内浓度（高达0.6M）。sbd.Methanogenium cariaci，一种海洋物种。该化合物具有相容溶质的特征；它在生理pH值下呈中性电荷，并且高度溶解。当细胞在外源甘氨酸甜菜碱存在下生长时，生理相容性溶质N.ε-乙酰基-β-赖氨酸的合成受到抑制并且甘氨酸甜菜碱积累。 N.ε-乙酰基-β-赖氨酸是由来自三个系统发育家族的物种在高溶质浓度下合成的，这表明它可能在产甲烷菌中普遍存在。响应细胞外溶质浓度控制N.ε-乙酰基-.β-赖氨酸生物合成的能力表明产甲烷古细菌具有独特的渗透调节的β-氨基酸生物合成途径。
Methanosarcina thermophila, a nonmarine methanogenic archaebacterium, can grow in a range of saline concentrations. At less than 0.4 M NaCl, Ms. thermophila accumulated glutamate in response to increasing osmotic stress. At greater than 0.4 mM NaCl, this organism synthesized a modified .beta.-amino acid that was identified as N.epsilon.-acetyl-.beta.-lysine by NMR spectroscopy and ion-exchange HPLC. This .beta.-amino acid derivative accumulated to high intracellular concentrations (up to 0.6 M) in Ms. thermophila and in another methanogen examined.sbd.Methanogenium cariaci, a marine species. The compound has features that are characteristic of a compatible solute; it is neutrally charged at physiological pH and it is highly soluble. When the cells were grown in the presence of exogenous glycine betaine, a physiological compatible solute, N.epsilon.-acetyl-.beta.-lysine synthesis was repressed and glycine betaine was accumulated. N.epsilon.-Acetyl-.beta.-lysine was synthesized by species from three phylogenetic families when grown in high solute concentrations, suggesting that it may be ubiquitous among the methanogens. The ability to control the biosynthesis of N.epsilon.-acetyl-.beta.-lysine in response to extracellular solute concentration indicates that the methanogenic archaebacteria have a unique .beta.-amino acid biosynthetic pathway that is osmotically regulated.