PROTEIN SYNTHESIS IN LEISHMANIA

描述(申请人提供)：人类利什曼病是由利什曼原虫引起的。在这种原生动物寄生虫中，转录的启动不是基因调控的主要方式。因此，转录后控制蛋白表达的途径是至关重要的，这对毒力至关重要。成熟mRNAs的非翻译区可以对其他生物的mRNA新陈代谢的几个方面产生重大影响。我们的长期目标是确定利什曼原虫起始密码子近端序列影响翻译和/或信使核糖核酸稳定性的一般原则。我们对200个利什曼原虫基因进行了生物信息学分析，发现了在翻译起始密码子附近流行的六聚体核苷酸。进一步的分析表明，六聚体是五个扩展序列基序的组成部分，可能是最近描述的脊椎动物利什曼原虫等效于“转录后操纵子”。我们假设利什曼原虫序列基序协调基因af的表达，即前mRNAs的性质。为了验证上述理论，将具有代表性的序列基序克隆到报告基因的上游，电击入利什曼原虫，并选择稳定的寄生虫细胞系。基序对mRNA稳定性和/或翻译的影响将在前鞭毛体、后周期和无鞭毛体发育阶段确定。这些研究可能导致发现新的信使核糖核酸代谢调节剂，从而进一步加深我们对利什曼原虫转录后基因调控的理解。

DESCRIPTION (provided by the applicant): Human leishmaniasis is caused by the Leishmania spp. In this protozoan parasite, initiation of transcription is not a major mode of gene regulation. Consequently, post-transcriptional pathways for controlling protein expression, which is critical for virulence, are of utmost importance. Untranslated regions of mature mRNAs can have major effects on several aspects of mRNA metabolism in other organisms. Our long-term goals are to determine general principles by which initiation-codon proximal sequences influence translation and/or mRNA stability in Leishmania. We performed bioinformatic analysis of two hundred Leishmania genes, and discovered hexamer nucleotides that were popular in regions close to translation initiation codons. Further analysis revealed that the hexamers were components of five extended sequence motifs that might be Leishmania equivalents of "post-transcriptional operons" recently describe, vertebrates. We hypothesize that the Leishmania sequence motifs coordinate expression of genes af, naturation of pre-mRNAs. To test the theories (above) representative sequence motifs will be cloned upstream of reporter genes, electroporated into Leishmania, and stable cell lines of parasites selected. The influence of the motifs on mRNA stability and/or translation will be determined in promastigote, metacyclic, and amastigote developmental stages. These studies are likely to lead to discovery of novel regulators of mRNA metabolism, thereby furthering our understanding of post-transcriptional gene regulation in Leishmania.