The procyclin-associated genes of Trypanosoma brucei are not essential for cyclical transmission by tsetse
The procyclin-associated genes of Trypanosoma brucei are not essential for cyclical transmission by tsetse
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DOI：
10.1016/j.molbiopara.2006.07.005
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发表时间：
2006-12-01
影响因子：
1.5
通讯作者：
Roditi, Isabel
中科院分区：
文献类型：
--
作者：
Haenni, Simon;Renggli, Christina Kunz;Roditi, Isabel
EP和GPEET原环素是采采蝇（Glossina spp.）中肠布氏锥虫的主要表面糖蛋白。原环素基因位于多顺反子转录单位的起始处，并且随后是至少一个原环素相关基因（PAG）。在X染色体的一个拷贝上的EP/PAG 1基因座以三个基因EP 1、EP 2和PAG 1开始;该单元的末端先前未被表征。X染色体的另一个拷贝上的EP/PAG 2基因座含有相同的前环素基因，随后是PAG 2和PAG 4。在这里，我们发现AnTat 1.1中的EP/PAG 1基因座必须由另外三个PAG延伸，我们将其命名为PAG 5，PAG 2 * 和PAG 4。EP/PAG 2基因座最有可能是从EP/PAG 1基因座通过从PAG 1到PAG 2 * 内缺失片段而进化而来的。染色体VI的两个拷贝上的原环素基因座是不可区分的，并且包含基因GPEET、EP 3、PAG 3和GRESAG2.1。PAG 1、PAG 2和PAG 3的mRNA水平在血流形式向前循环形式的分化期间瞬时增加。出乎意料的是，在原环蛋白基因座中缺乏所有八个PAG的PAG敲除克隆的原环形式可由Glossina morsitans传播。此外，缺失突变体仍然可以建立中肠感染时，竞争与完整的PAG的标记克隆。当采采蝇感染血流形式的缺失突变体时，也可能发生循环传播，这表明PAG对于体内血流向原循环形式的分化不是必需的。(c)2006 Elsevier B. V.保留所有权利。
EP and GPEET procyclins are the major surface glycoproteins of Trypanosoma brucei in the midgut of tsetse flies (Glossina spp.). The procyclin genes are located at the beginning of polycistronic transcription units and are followed by at least one procyclin-associated gene (PAG). The EP/PAG1 locus on one copy of chromosome X begins with the three genes EP1, EP2 and PAG1; the end of this unit has not been characterized previously. The EP/PAG2 locus on the other copy of chromosome X contains the same procyclin genes followed by PAG2 and PAG4. Here we show that the EP/PAG1 locus in AnTat1.1 has to be extended by three more PAGs, which we named PAG5, PAG2* and PAG4. The EP/PAG2 locus most likely evolved from the EP/PAG1 locus by deletion of a fragment from within PAG1 to PAG2*. The procyclin loci on the two copies of chromosome VI are indistinguishable, and contain the genes GPEET, EP3, PAG3 and GRESAG2.1. The mRNA levels of PAG1, PAG2 and PAG3 are transiently increased during differentiation of bloodstream forms to procyclic forms. Unexpectedly, procyclic forms of a PAG knockout clone lacking all eight PAGs in the procyclin loci were transmissible by Glossina morsitans. Furthermore, the deletion mutant could still establish midgut infections when competing with a tagged clone with the full complement of PAGs. Cyclical transmission was also possible when tsetse flies were infected with bloodstream forms of the deletion mutant, demonstrating that the PAGs are not essential for the differentiation of bloodstream to procyclic forms in vivo. (c) 2006 Elsevier B.V. All rights reserved.