BEET YELLOWS CLOSTEROVIRUS - COMPLETE GENOME STRUCTURE AND IDENTIFICATION OF A LEADER PAPAIN-LIKE THIOL PROTEASE
BEET YELLOWS CLOSTEROVIRUS - COMPLETE GENOME STRUCTURE AND IDENTIFICATION OF A LEADER PAPAIN-LIKE THIOL PROTEASE
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DOI：
10.1006/viro.1994.1034
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发表时间：
1994-01-01
期刊：
影响因子：
3.7
通讯作者：
ATABEKOV, JG
中科院分区：
文献类型：
--
作者：
AGRANOVSKY, AA;KOONIN, EV;ATABEKOV, JG
测定了甜菜黄化梭状病毒（BYV）RNA 5′端8734个核苷酸的序列，完成了BYV基因组15,480个核苷酸的全序列。序列的5′端三分之二被两个重叠的开放阅读框（ORF）1a和1b占据。编码产品计算Mr 295 K和48 K分别。ORF 1a中终止密码子周围的RNA序列显示了许多动物和植物病毒中核糖体移码信号的典型结构元件。预计ORF 1b产物通过+1核糖体移码表达为348 K ORF 1a/1b融合蛋白。这种推定的蛋白质含有甲基转移酶、RNA解旋酶和RNA依赖性RNA聚合酶结构域的阵列，这些结构域在正链RNA病毒的辛德比斯样超组中是保守的。BYV的348 K蛋白比最密切相关的病毒（烟草病毒和烟草病毒）的推定复制酶长约1300个氨基酸，分布在两个独特的区域之间，一个位于N末端，另一个位于中心部分。N-末端结构域显示出与马铃薯Y病毒属的辅助组分木瓜蛋白酶样蛋白酶的序列相似性。通过体外翻译编码BYV ORF 1a产物N端92 K肽的T7转录物，我们发现在Gly-Gly二肽处切割，从翻译产物中释放出588个氨基酸的N端片段。预测的催化残基Cys-509和His-569或Gly-588在切割位点的定点诱变完全废除了切割。348 K蛋白的中心独特区域包含一个与HIV和其他慢病毒的天冬氨酸蛋白酶有着很大相似性的结构域。如前所述，BYV基因组的3′-末端部分包含另外7个ORF，其中一个编码与HSP 70细胞热休克蛋白相关的蛋白，而另外两个编码衣壳蛋白及其分叉拷贝。因此，尽管与辛德毕斯样病毒有明显的进化关系，但BYV包含从不同来源吸收的基因组模块的集合，并具有独特的表达策略。
The sequence of 8734 nucleotides (nt) from the 5′-end of the beet yellows closterovirus (BYV) RNA was determined to complete the 15,480-nt sequence of the virus genome. The 5′-terminal two-thirds of the sequence are occupied by two overlapping open reading frames (ORFs) 1a and 1b. encoding products with calculatedMrof 295K and 48K, respectively. The RNA sequence surrounding the stop codon in ORF 1a shows structural elements typical of ribosomal frameshifting signals in a number of animal and plant viruses. It is predicted that the ORF 1b product is expressed via a +1 ribosomal frameshifting as the 348K ORF 1a/1b fusion protein. This putative protein contains the array of methyltransferase, RNA helicase, and RNA-dependent RNA polymerase domains that is conserved in the Sindbis-like super-group of positive-strand RNA viruses. The 348K protein of BYV is longer than the putative replicases of the most closely related viruses (tobra- and tobamoviruses) by about 1300 amino acids distributed between two unique regions, one at the N-terminus, and the other in the central portion. The N-terminal domain showed sequence similarity to the helper component papain-like protease of potyviruses. By usingin vitrotranslation of the T7 transcripts encoding the N-terminal 92K peptide of the BYV ORF la product, we found that the N-terminal fragment of 588 amino acids is released from the translation product by cleavage at the Gly-Gly dipeptide. Site-directed mutagenesis of either of the predicted catalytic residues Cys-509 and His-569 or of the Gly-588 at the cleavage site completely abolished the cleavage. The central unique region of the 348K protein contains a domain distantly resembling the aspartic protease of HIV and other lentiviruses. As shown previously, the 3′-terminal portion of the BYV genome encompasses seven more ORFs, one of which codes for a protein related to the HSP70 cell heat shock proteins, whereas two others encode the capsid protein and its diverged copy. Thus, despite the apparent evolutionary relationship with Sindbis-like viruses, BYV comprises a collection of genomic modules absorbed from different sources and has a unique expression strategy.