Li Y, Lu Z, Sun L, Ropp S, Kutish G F, Rock D L, Van Etten J L
Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583-0722, USA.
Virology. 1997 Oct 27;237(2):360-77. doi: 10.1006/viro.1997.8805.
This report completes a preliminary analysis of the sequence of the 330,740-bp chlorella virus PBCV-1 genome, the largest virus genome to be sequenced to date. The PBCV-1 genome is 57% the size of the genome from the smallest self-replicating organism, Mycoplasma genitalium. Analysis of 74 kb of newly sequenced DNA, from the right terminus of the PBCV-1 genome, revealed 153 open reading frames (ORFs) of 65 codons or longer. Eighty-five of these ORFs, which are evenly distributed on both strands of the DNA, were considered major ORFs. Fifty-nine of the major ORFs were separated by less than 100 bp. The largest intergenic distance was 729 bp, which occurred between two ORFs located in the 2.2-kb inverted terminal repeat region of the PBCV-1 genome. Twenty-seven of the 85 major ORFs resemble proteins in databases, including the large subunit of ribonucleotide diphosphate reductase, ATP-dependent DNA ligase, type II DNA topoisomerase, a helicase, histidine decarboxylase, dCMP deaminase, dUTP pyrophosphatase, proliferating cell nuclear antigen, a transposase, fungal translation elongation factor 3 (EF-3), UDP glucose dehydrogenase, a protein kinase, and an adenine DNA methyltransferase and its corresponding DNA site-specific endonuclease. Seventeen of the 153 ORFs resembled other PBCV-1 ORFs, suggesting that they represent either gene duplications or gene families.
本报告完成了对330,740碱基对的小球藻病毒PBCV - 1基因组序列的初步分析，该基因组是迄今为止已测序的最大病毒基因组。PBCV - 1基因组的大小是最小的自我复制生物——生殖支原体基因组大小的57%。对来自PBCV - 1基因组右端新测序的74 kb DNA的分析，揭示了153个65个密码子或更长的开放阅读框（ORF）。其中85个ORF均匀分布在DNA的两条链上，被认为是主要ORF。59个主要ORF之间的间隔小于100 bp。最大的基因间隔距离为729 bp，发生在位于PBCV - 1基因组2.2 kb反向末端重复区域的两个ORF之间。85个主要ORF中的27个与数据库中的蛋白质相似，包括核糖核苷酸二磷酸还原酶的大亚基、ATP依赖性DNA连接酶、II型DNA拓扑异构酶、解旋酶、组氨酸脱羧酶、dCMP脱氨酶、dUTP焦磷酸酶、增殖细胞核抗原、转座酶、真菌翻译延伸因子3（EF - 3）、UDP葡萄糖脱氢酶、蛋白激酶以及腺嘌呤DNA甲基转移酶及其相应的DNA位点特异性内切酶。153个ORF中的17个与其他PBCV - 1 ORF相似，表明它们代表基因重复或基因家族。
