POLY(A) POLYMERASE AND A DISSOCIABLE POLYADENYLATION STIMULATORY FACTOR ENCODED BY VACCINIA VIRUS
POLY(A) POLYMERASE AND A DISSOCIABLE POLYADENYLATION STIMULATORY FACTOR ENCODED BY VACCINIA VIRUS
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DOI：
10.1016/0092-8674(91)90048-4
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发表时间：
1991-09-20
期刊：
影响因子：
64.5
通讯作者：
MOSS, B
中科院分区：
文献类型：
--
作者：
GERSHON, PD;AHN, BY;MOSS, B
真核细胞中产生的 mRNA 通常具有转录后添加的 3' Poly(A) 尾。 为了研究 3' Poly(A) 的形成机制，我们鉴定了两种痘苗病毒编码的多肽 VP55 和 VP39 的基因。 引物依赖性聚腺苷酸化活性仅与纯化的 VP55-VP39 异二聚体相关，尽管该异二聚体对柱色谱和甘油梯度沉降稳定，但很容易被 VP55 N 端肽的抗体解离。 Poly(A) 聚合酶活性与免疫纯化的 VP55 相关，但与免疫纯化或色谱纯化的 VP39 无关。 然而，VP39 是形成长聚 (A) 分子所必需的，与纯化的 VP55 或低浓度的异二聚体结合，并且显示可结合游离聚 (A)。 因此，催化多肽和可解离的聚腺苷酸结合刺激因子各自有助于聚腺苷酸尾的形成。 在序列数据库中没有检测到任一多肽的原核或真核同源物，这与先前报道的来自任何来源的聚(A)聚合酶基因的不存在一致。
mRNA made in eukaryotic cells typically has a 3' poly(A) tail that is added posttranscriptionally. To investigate mechanisms by which 3' poly(A) is formed, we identified the genes for the two vaccinia virus-encoded polypeptides, VP55 and VP39. Primer-dependent polyadenylation activity was associated exclusively with purified VP55-VP39 heterodimer, which, although stable to column chromatography and glycerol gradient sedimentation, was readily dissociated by antibody to an N-terminal peptide of VP55. Poly(A) polymerase activity was associated with immunopurified VP55, but not with immunopurified or chromatographically purified VP39. VP39 was, however, required for the formation of long poly(A) molecules, in conjunction with either purified VP55 or low concentrations of the heterodimer, and was shown to bind free poly(A). Thus, a catalytic polypeptide and a dissociable poly(A)-binding stimulatory factor each contribute to poly(A) tail formation. No prokaryotic or eukaryotic homologs of either polypeptide were detected in sequence data bases, consistent with the absence of previously reported poly(A) polymerase genes from any source.