Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.
Astrobiology. 2010 Dec;10(10):989-1000. doi: 10.1089/ast.2010.0484.
It has been hypothesized in this journal and elsewhere, based on surveys of published data from prebiotic synthesis experiments and carbonaceous meteorite analyses, that basic amino acids such as lysine and arginine were not abundant on prebiotic Earth. If the basic amino acids were incorporated only rarely into the first peptides formed in that environment, it is important to understand what protobiotic chemistry is possible in their absence. As an initial test of the hypothesis that basic amino acid negative [BAA(-)] proteins could have performed at least a subset of protobiotic chemistry, the current work reports on a survey of 13 archaeal and 13 bacterial genomes that has identified 61 modern gene sequences coding for known or putative proteins not containing arginine or lysine. Eleven of the sequences found code for proteins whose functions are well known and important in the biochemistry of modern microbial life: lysine biosynthesis protein LysW, arginine cluster proteins, copper ion binding proteins, bacterial flagellar proteins, and PE or PPE family proteins. These data indicate that the lack of basic amino acids does not prevent peptides or proteins from serving useful structural and biochemical functions. However, as would be predicted from fundamental physicochemical principles, we see no fossil evidence of prebiotic BAA(-) peptide sequences capable of interacting directly with nucleic acids.
本期刊物和其他地方曾提出假设，根据对前生物合成实验和碳质陨石分析的已发表数据的调查，基本氨基酸（如赖氨酸和精氨酸）在原始地球上并不丰富。如果这些碱性氨基酸仅偶尔掺入该环境中形成的第一批肽中，那么了解在它们缺失的情况下可能存在哪些原始生物化学就很重要。作为对碱性氨基酸阴性 [BAA(-)] 蛋白质至少可以执行原始生物化学的一部分这一假设的初步检验，当前的工作报告了对 13 种古细菌和 13 种细菌基因组的调查，该调查确定了 61 个现代基因序列，这些序列编码已知或假定的不含精氨酸或赖氨酸的蛋白质。发现的 11 个序列编码的蛋白质其功能在现代微生物生命的生物化学中是众所周知且重要的：赖氨酸生物合成蛋白 LysW、精氨酸簇蛋白、铜离子结合蛋白、细菌鞭毛蛋白和 PE 或 PPE 家族蛋白。这些数据表明，缺乏碱性氨基酸并不会阻止肽或蛋白质发挥有用的结构和生化功能。然而，正如基本物理化学原理所预测的那样，我们没有发现能够直接与核酸相互作用的原始 BAA(-) 肽序列的化石证据。
