Abstract

Cyanobacteria are among the earth’s oldest known living groups of organisms and can form layered accretions called microbialites, found in both the fossil record and existing lakes. Studies of cyanobacterial biochemical processes help to understand the evolution of life on earth. The conserved metabolism of cyanobacterial species includes the biosynthesis of unusual nonprotein amino acids such as N-(2-aminoethyl)glycine, hypothesized to have constituted an early form of genetic information in cells. Pavilion Lake in British Columbia, Canada, hosts a population of unique, actively growing microbialites covered in biofilms dominated by cyanobacteria. We hypothesized that the living microbial communities produce dinitrogenous nonprotein amino acids, such as N-(2-aminoethyl)glycine and its structural isomers β-N-methylamino-l-alanine, 2,4-diaminobutyric acid and β-aminomethyl-l-alanine. We analyzed samples in sediment traps collected between 2007 and 2014 in depths ranging from 11 to 46 m. N-(2-aminoethyl)glycine, 2,4-diaminobutyric acid and β-aminomethyl-l-alanine were found in highest concentration in the shallowest microbialite biofilms with a maximum of 22 ng/g, 33 ng/g and 0.4 ng/g, respectively. In contrast, the concentration of β-N-methylamino-l-alanine was highest in collections between 18 and 26 m depths and only β-N-methylamino-l-alanine was found in the deepest water collections. These data provide evidence indicating that the production of these nonprotein amino acids is highly conserved through the evolution of cyanobacteria and suggest that the nitrogen-rich metabolites may have had both an important role in ancient and modern cyanobacterial metabolism. Further research will determine the role of N-(2-aminoethyl)glycine and its isomers in early life metabolism and their current function in photosynthetic cells.

中文翻译：

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现代蓝细菌微恶岩中的早期地球非蛋白质氨基酸代谢产物

摘要

蓝细菌是地球上已知最古老的生物体之一，可以形成化石记录和现有湖泊中发现的称为微生物的层状增生物。对蓝细菌生化过程的研究有助于了解地球上生命的演变。蓝细菌物种的保守代谢包括不寻常的非蛋白质氨基酸（例如N-（2-氨基乙基）甘氨酸）的生物合成，这些氨基酸被认为已构成细胞中遗传信息的早期形式。加拿大不列颠哥伦比亚省的亭子湖（Pavilion Lake）拥有一群独特的，活跃生长的微生物，这些微生物被蓝细菌主导的生物膜覆盖。我们假设生活的微生物群落产生二氮非蛋白质氨基酸，例如N-（2-氨基乙基）甘氨酸及其结构异构体β- N-甲基氨基-1-丙氨酸，2，4-二氨基丁酸和β-氨基甲基-1-丙氨酸。我们分析了2007年至2014年之间收集的深度在11至46 m范围内的沉积物陷阱中的样本。N-（2-氨基乙基）甘氨酸，2,4-二氨基丁酸和β-氨基甲基-1-丙氨酸在最浅的微晶石生物膜中浓度最高，最大为22 ng / g，33 ng / g和0.4 ng / g。 g，分别。相反，β-的浓度Ñ -methylamino-升丙氨酸最高在18米26米的深度之间，只有β-集合Ñ -methylamino-升在最深的水域中发现了丙氨酸。这些数据提供了证据，表明通过蓝细菌的进化，这些非蛋白质氨基酸的产生是高度保守的，并表明富含氮的代谢产物可能在古代和现代蓝细菌的代谢中都起着重要作用。进一步的研究将确定N-（2-氨基乙基）甘氨酸及其异构体在早期代谢中的作用及其在光合作用细胞中的当前功能。