Disruption of largest subunit RNA polymerase II genes in Trypanosoma brucei.
Disruption of largest subunit RNA polymerase II genes in Trypanosoma brucei.
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布氏锥虫最大亚基 RNA 聚合酶 II 基因的破坏。
DOI：
10.1128/mcb.13.6.3734-3743.1993
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发表时间：
1993
影响因子：
5.3
通讯作者：
VanderPloeg,LH
中科院分区：
文献类型：
--
作者：
Chung,HM;Lee,MG;Dietrich,P;Huang,J;VanderPloeg,LH
布氏锥虫（原种427-60）基因组中编码两种类型的最大亚基RNA聚合酶II（pol II）基因（pol IIA和pol IIB），其不同之处在于3个氨基酸取代。因此，提出了前环酸性重复蛋白（PARP）和变异表面糖蛋白（VSG）基因的α-鹅膏蕈碱抗性转录涉及pol II最大亚基的修饰的α-鹅膏蕈碱抗性形式。另外，pol I可以转录PARP和VSG基因。为了区分这两种模型，我们删除了N-末端结构域（约三分之一的多肽），它编码的氨基酸取代，区分pol IIA和pol IIB基因，在两个pol IIB等位基因。pol IIB-锥虫仍然通过α-鹅膏蕈碱抗性RNA聚合酶转录昆虫型锥虫中的PARP基因和VSG基因启动子区，而对照管家基因以α-鹅膏蕈碱敏感的方式转录，推测是通过pol IIA。我们的结论是，α-鹅膏菌素抗性的转录蛋白编码基因在布氏锥虫不是由一个分歧形式的最大亚基的pol II和pol IIA和pol IIB基因的存在是不是必不可少的锥虫活力。这一结论进一步得到以下发现的支持：个体锥虫变体对于先前鉴定的氨基酸取代表现出等位基因异质性，并且多态性氨基酸的各种排列产生至少四种不同类型的最大亚基pol II基因。PARP基因和VSG基因启动子区通过pol IIB-锥虫中的α-鹅膏蕈碱抗性RNA聚合酶的表达为pol I转录这些基因提供了证据。
Two types of largest subunit RNA polymerase II (pol II) genes (pol IIA and pol IIB), differing in 3 amino acid substitutions, are encoded in the Trypanosoma brucei (stock 427-60) genome. As a result, the α-amanitin-resistant transcription of the procyclic acidic repetitive protein (PARP) and variant surface glycoprotein (VSG) genes was proposed to involve a modified, α-amanitin-resistant form of the largest subunit of pol II. Alternatively, pol I could transcribe the PARP and VSG genes. To discriminate between these two models, we deleted the N-terminal domain (about one-third of the polypeptide), which encodes the amino acid substitutions which discriminated the pol IIA and pol IIB genes, at both pol IIB alleles. The pol IIB-trypanosomes still transcribe the PARP genes and the VSG gene promoter region in insect-form trypanosomes by α-amanitin-resistant RNA polymerases, while control housekeeping genes are transcribed in an α-amanitin-sensitive manner, presumably by pol IIA. We conclude that the α-amanitin-resistant transcription of protein coding genes inT. brucei is not mediated by a diverged form of the largest subunit of pol II and that the presence of both the pol IIA and pol IIB genes is not essential for trypanosome viability. This conclusion was further supported by the finding that individual trypanosome variants exhibited allelic heterogeneity for the previously identified amino acid substitutions and that various permutations of the polymorphic amino acids generate at least four different types of largest subunit pol II genes. The expression of the PARP genes and the VSG gene promoter region by α-amanitin-resistant RNA polymerases in the pol IIB-trypanosomes provides evidence for transcription of these genes by pol I.