法国巴黎萨克莱大学Philippe Marliere课题组的最新研究揭示了基于氨基腺嘌呤siphoviruses的非典型DNA合成。这一研究成果发表在2021年4月30日出版的国际学术期刊《科学》上。

噬菌体基因组中包含了所有生命形式中广泛存在的核碱基化学多样性。感染宿主的某些DNA病毒（例如蓝细菌、蛋白细菌和放线菌）具有氨基腺嘌呤完全取代腺嘌呤的现象，从而与胸腺嘧啶形成三个氢键，这违反了Watson-Crick配对规则。与含有3'-核酸外切酶但缺乏5'-核酸外切酶活性的细菌DNA聚合酶I Klenow片段同源的氨基腺嘌呤编码DNA聚合酶，被发现在以胸腺嘧啶为模板的脱氧核苷三磷酸掺入过程中优先利用氨基腺嘌呤而不是腺嘌呤。

聚合酶基因与生物合成酶的基因同时发生，该生物合成酶在各种各样的剑孢病毒噬菌体中产生氨基腺嘌呤脱氧核苷酸。聚合酶和生物合成酶的系统同源聚类表明，自古进化阶段以来，氨基腺嘌呤就与腺嘌呤一起伴随DNA复制。

附：英文原文

Title: Noncanonical DNA polymerization by aminoadenine-based siphoviruses

Author: Valerie Pezo, Faten Jaziri, Pierre-Yves Bourguignon, Dominique Louis, Deborah Jacobs-Sera, Jef Rozenski, Sylvie Pochet, Piet Herdewijn, Graham F. Hatfull, Pierre-Alexandre Kaminski, Philippe Marliere

Issue&Volume: 2021/04/30

Abstract: Bacteriophage genomes harbor the broadest chemical diversity of nucleobases across all life forms. Certain DNA viruses that infect hosts as diverse as cyanobacteria, proteobacteria, and actinobacteria exhibit wholesale substitution of aminoadenine for adenine, thereby forming three hydrogen bonds with thymine and violating Watson-Crick pairing rules. Aminoadenine-encoded DNA polymerases, homologous to the Klenow fragment of bacterial DNA polymerase I that includes 3′-exonuclease but lacks 5′-exonuclease, were found to preferentially select for aminoadenine instead of adenine in deoxynucleoside triphosphate incorporation templated by thymine. Polymerase genes occur in synteny with genes for a biosynthesis enzyme that produces aminoadenine deoxynucleotides in a wide array of Siphoviridae bacteriophages. Congruent phylogenetic clustering of the polymerases and biosynthesis enzymes suggests that aminoadenine has propagated in DNA alongside adenine since archaic stages of evolution.

DOI: 10.1126/science.abe6542

Source: https://science.sciencemag.org/content/372/6541/520