Flinn H M, Smith D F
Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, UK.
Nucleic Acids Res. 1992 Feb 25;20(4):755-62. doi: 10.1093/nar/20.4.755.
We have isolated and characterised a differentially-regulated gene family in the protozoan parasite Leishmania major. The family contains 5 genes linked within a 10Kb region of the genome: three of the genes are closely related in DNA sequence, the other two have only limited homology. Post-transcriptional control of the differential expression pattern is suggested by detection of precursor RNA molecules containing intergenic sequences and evidence that mature mRNA molecules contain a 35nt spliced leader sequence at their 5' ends. These features support a model of polycistronic transcription in which the stability and differential processing of precursor RNA molecules determine the steady state levels of mature mRNA. We have identified several DNA sequence motifs within the gene family that have potential roles in differential processing and/or RNA stability: an alternative 5' splice acceptor site for trans-splicing; a putative polyadenylation site; and a region of potential secondary structure within 3' flanking sequences. The 3' sequence elements are conserved in those genes that share the same pattern of differential regulation. To our knowledge, this is the first example of coordinated differential-regulation of a non-identical gene cluster in Leishmania.
我们已经在原生动物寄生虫硕大利什曼原虫中分离并鉴定了一个差异调节基因家族。该家族包含5个基因，它们在基因组的10Kb区域内连锁：其中3个基因在DNA序列上密切相关，另外两个只有有限的同源性。通过检测含有基因间序列的前体RNA分子以及成熟mRNA分子在其5'端含有35nt剪接前导序列的证据，提示了差异表达模式的转录后控制。这些特征支持多顺反子转录模型，其中前体RNA分子的稳定性和差异加工决定了成熟mRNA的稳态水平。我们已经在该基因家族中鉴定了几个在差异加工和/或RNA稳定性中具有潜在作用的DNA序列基序：一个用于反式剪接的替代5'剪接受体位点；一个假定的聚腺苷酸化位点；以及3'侧翼序列内的一个潜在二级结构区域。3'序列元件在那些具有相同差异调节模式的基因中是保守的。据我们所知，这是利什曼原虫中一个不同基因簇协调差异调节的首个例子。
