Suyama Y, Wong S, Campbell D A
Department of Biology, University of Pennsylvania, Philadelphia 19104, USA.
Biochim Biophys Acta. 1998 Mar 9;1396(2):138-42. doi: 10.1016/s0167-4781(97)00197-8.
The genes for three new tRNA and a 5S RNA were identified from a genomic DNA clone of 917 nucleotide pairs from the protozoon Leishmania tarentolae. They were encoded in the following order. The transcriptional directions and anticodons are in parentheses: tRNA(Val) (CAC-->)-5SRNA (-->)-tRNA(His) (<--GUG)-tRNA(Phe) (GAA-->). The tRNA(His) and tRNA(Phe) sequences have not been reported previously in trypanosomatid organisms. By northern analysis, tRNA(Val) and tRNA(Phe) were equally distributed between the cytosol and mitochondria, while tRNA(His) was less abundant in mitochondria than in the cytosol. Accordingly, the latter tRNA is classified as Import restricted (Impr). As shown before, 5S RNA was not imported. Recently, Mahapatra and Adhya [S. Mahapatra, T. Ghosh, S. Adhya, Nucl. Acids Res. 22 (1994) 3381-3386; S. Mahapatra, S. Adhya, J. Biol. Chem. 271 (1996) 20432-20437] have developed an in vitro import system in Leishmania and suggested that the D-loop sequence could serve as the import determinant. We examined all available tRNA gene sequences in trypanosomatids but found no apparent consensus within the D-loop that might account for tRNA-import regulation.
从来自原虫大利什曼原虫的一个917个核苷酸对的基因组DNA克隆中鉴定出了三种新的tRNA基因和一个5S RNA基因。它们按以下顺序编码。转录方向和反密码子在括号内：tRNA(Val) (CAC→)-5SRNA (→)-tRNA(His) (←GUG)-tRNA(Phe) (GAA→)。tRNA(His)和tRNA(Phe)序列此前在锥虫类生物中尚未见报道。通过Northern分析，tRNA(Val)和tRNA(Phe)在胞质溶胶和线粒体之间均匀分布，而tRNA(His)在线粒体中的丰度低于胞质溶胶。因此，后一种tRNA被归类为进口受限型（Impr）。如前所示，5S RNA不被导入。最近，马哈帕特拉和阿迪亚[S. Mahapatra, T. Ghosh, S. Adhya, Nucl. Acids Res. 22 (1994) 3381 - 3386; S. Mahapatra, S. Adhya, J. Biol. Chem. 271 (1996) 20432 - 20437]开发了一种利什曼原虫的体外导入系统，并提出D环序列可作为导入决定因素。我们检查了锥虫类中所有可用的tRNA基因序列，但在D环内未发现可能解释tRNA导入调控的明显共识。
