A SMALL DELETION DISTANT FROM A SPLICE OR POLYADENYLATION SITE DRAMATICALLY ALTERS PRE-MESSENGER-RNA PROCESSING IN REGION-E3 OF ADENOVIRUS
A SMALL DELETION DISTANT FROM A SPLICE OR POLYADENYLATION SITE DRAMATICALLY ALTERS PRE-MESSENGER-RNA PROCESSING IN REGION-E3 OF ADENOVIRUS
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DOI：
10.1128/jvi.61.12.3938-3945.1987
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发表时间：
1987-12-01
影响因子：
5.4
通讯作者：
WOLD, WSM
中科院分区：
文献类型：
--
作者：
BHAT, BM;WOLD, WSM
腺病毒的 E3 复合转录单元编码具有不同外显子结构的重叠 mRNA（a 至 i）。主要的mRNA是a（约占总数的40%）和c（约15%），它们被剪接一次，以及f（约15%）和h（约25%），它们被剪接两次。 mRNA a 使用上游 E3A 聚腺苷酸化位点，其他 mRNA 使用下游 E3B 聚腺苷酸化位点。我们分析了病毒缺失突变体，以确定 E3 区替代前 mRNA 加工中重要的序列。我们的主要发现是 dl742 中的 64 个碱基对缺失主要导致 mRNA f 和 h 的形成。 mRNA a 和 c 是大麦制造的，dl742 不会删除剪接位点或多聚腺苷酸化位点。因此，删除的序列必须在替代的前mRNA加工中发挥作用，独立于实际剪接和聚腺苷酸化位点的信号。 dl742 合成 mRNA a 的缺乏似乎并不是由于 E3A 多聚腺苷酸化信号的缺陷所致，而是由于剪接活性的增加，导致以单剪接的 mRNA a 和 c 为代价合成双剪接的 mRNA f 和 h。这表明，在野生型情况下，E3A相对于E3B聚腺苷酸化位点的使用频率可能由剪接速率以及可能的E3A位点处的切割-聚腺苷酸化速率决定。
The E3 complex transcription unit of adenovirus encodes overlapping mRNAs (a to i) with different exon structures. The major mRNAs are a (.apprx. 40% of the total) and c (.apprx. 15%), which are spliced once, and f (.apprx. 15%) and h (.apprx. 25%), which are spliced twice. mRNA a uses the upstream E3A polyadenylation site, and the other mRNAs use the downstream E3B polyadenylation site. We analyzed virus deletion mutants to identify sequences important in alternative pre-mRNA processing in region E3. Our main finding is that a 64-base-pair deletion in dl742 causes mainly mRNAs f and h to be formed. mRNAs a and c are barley made, dl742 does not delete either a splice site or a polyadenylation site. Thus, the sequences deleted must function in alternative pre-mRNA processing independently of the signals at the acutal splice and polyadenylation sites. The lack of synthesis of mRNA a by dl742 does not appear to result from a defect in the E3A polyadenylation signal but rather from an increase in splicing activity which results in the synthesis of doubly spliced mRNAs f and h at the expense of singly spliced mRNAs a and c. This suggests, in the wild-type situation, that the frequency of use of the E3A, versus the E3B polyadenylation site may be determined by the rate of splicing, as well as, presumably, the rate of cleavage-polyadenylation at the E3A site.