Koenig-Martin E, Yamage M, Roditi I
Kernforschungszentrum Karlsruhe, Institut für Genetik und Toxikologie, FRG.
Mol Biochem Parasitol. 1992 Oct;55(1-2):135-45. doi: 10.1016/0166-6851(92)90134-6.
The procyclin genes of Trypanosoma brucei encode a family of glycoproteins expressed on the surface of procyclic forms of the parasite. These genes are present at different loci in tandem arrays of two or three copies depending on the strain. It has previously been shown that procyclin genes are transcribed from a promotor immediately upstream of the first procyclin gene in each cluster by an RNA polymerase that is resistant to high levels of alpha-amanitin. Here we show that additional genes, which we term procyclin-associated genes (PAGs), are located downstream of the procyclin genes and belong to the same alpha-amanitin-resistant polycistronic transcription units. A gene in the pro A locus, PAG 1, encodes a polypeptide that is related to the ESAG 6 and 7 proteins encoded in the VSG expression site. An unexpected feature of PAG 1 is that the major open reading frame of 405 amino acids only starts at position 1283 in the cDNA sequence and extends to the poly(A) tail. Sequences related to the 5' untranslated region of PAG 1 are also found downstream of procyclin genes in other loci, but the 3' coding region is unique to Pro A. This suggests that there are related PAGs which are coordinately transcribed with procyclin genes from different loci.
布氏锥虫的前环素基因编码一族糖蛋白，这些糖蛋白在该寄生虫前循环型的表面表达。根据菌株不同，这些基因以两个或三个拷贝的串联阵列形式存在于不同位点。此前已经表明，前环素基因由对高水平α-鹅膏蕈碱有抗性的RNA聚合酶从每个簇中第一个前环素基因紧邻上游的启动子转录而来。在此我们表明，我们称为前环素相关基因（PAGs）的其他基因位于前环素基因下游，并且属于相同的对α-鹅膏蕈碱有抗性的多顺反子转录单元。前A位点中的一个基因PAG 1编码一种与VSG表达位点中编码的ESAG 6和7蛋白相关的多肽。PAG 1的一个意外特征是405个氨基酸的主要开放阅读框仅在cDNA序列中的第1283位开始，并延伸至聚腺苷酸尾。在其他位点的前环素基因下游也发现了与PAG 1的5'非翻译区相关的序列，但3'编码区是前A位点所特有的。这表明存在与来自不同位点的前环素基因协同转录的相关PAGs。
