URMITE UM3, CNRS 7278, IRD 198, INSERM U1905, Institut Hospitalo-Universitaire Méditerranée Infection, Facultés de Médecine et de Pharmacie, Aix-Marseille Université, Marseille, France.
Intervirology. 2013;56(6):364-75. doi: 10.1159/000354557. Epub 2013 Oct 17.
Mimiviruses are giant viruses that infect phagocytic protists, including Acanthamoebae spp., which were discovered during the past decade. They are the current record holder among viruses for their large particle and genome sizes. One group is composed of three lineages, referred to as A, B and C, which include the vast majority of the Mimiviridae members. Cafeteria roenbergensis virus represents a second group, though the Mimiviridae family is still expanding. We analyzed the codon and amino acid usages in mimiviruses, as well as both the transfer RNA (tRNA) and amino acyl-tRNA synthetases. We confirmed that the codon and amino acid usages of these giant viruses are highly dissimilar to those in their amoebal host Acanthamoeba castellanii and are instead correlated with the high adenine and thymine (AT) content of Mimivirus genomes. We further describe that the set of tRNAs and amino acyl-tRNA synthetases in mimiviruses is globally not adapted to the codon and amino acid usages of these viruses. Notwithstanding, Leu(TAA)tRNA, present in several Mimivirus genomes and in multiple copies in some viral genomes, may complement the amoebal tRNA pool and may contribute to accommodate the viral AT-rich codons. In addition, we found that the genes most highly expressed at the beginning of the Mimivirus replicative cycle have a nucleotide content more adapted to the codon usage in A.castellanii.
巨型病毒是感染吞噬性原生动物的病毒，包括棘阿米巴属，这些病毒是在过去十年中发现的。它们是目前病毒中颗粒和基因组大小的记录保持者。其中一组由三个谱系组成，称为 A、B 和 C，它们包含了绝大多数的 mimiviridae 成员。尽管 mimiviridae 家族仍在不断扩大，但 Cafeteria roenbergensis 病毒代表了第二个群体。我们分析了 mimiviruses 的密码子和氨基酸使用情况，以及转移 RNA（tRNA）和氨酰-tRNA 合成酶。我们证实，这些巨型病毒的密码子和氨基酸使用情况与它们的阿米巴宿主棘阿米巴属非常不同，而是与 mimivirus 基因组中的高腺嘌呤和胸腺嘧啶（AT）含量相关。我们进一步描述了 mimiviruses 中的 tRNA 和氨酰-tRNA 合成酶集合在全球范围内不适应这些病毒的密码子和氨基酸使用情况。尽管如此，Leu(TAA)tRNA 存在于几种 mimivirus 基因组中，并且在一些病毒基因组中存在多个拷贝，可能补充了阿米巴 tRNA 池，并有助于容纳病毒富含 AT 的密码子。此外，我们发现 mimivirus 复制周期开始时表达水平最高的基因具有更适应棘阿米巴属密码子使用的核苷酸含量。
