Nelson Martha J, Dang Yunkun, Filek Elena, Zhang Zhaoduo, Yu Vionnie Wing Chi, Ishida Ken-ichiro, Green Beverley R
Botany Department, University of British Columbia, #3529-6270 University Blvd., Vancouver, B.C., Canada V6T 1Z4.
Gene. 2007 May 1;392(1-2):291-8. doi: 10.1016/j.gene.2007.01.018. Epub 2007 Feb 7.
The dinoflagellate chloroplast genome is unique in that the genes are found on small circular DNA molecules carrying from one to three genes. In addition, only 14 of the typical chloroplast-located genes have so far been discovered on minicircles, while a number have been transferred to the nucleus. We have sequenced four new minicircles from the dinoflagellate Heterocapsa triquetra, three of which carry a single protein-coding gene (psbD, psbE, petD) and one that appears to be an "empty" circle. Using the tRNA prediction programs ARAGORN and tRNAscan-SE, tRNA-Met was found in the petD circle immediately downstream of the end of petD, while tRNA-Trp and tRNA-Pro were detected in the psbE and petD circles as well as in several chimeric circles of H. triquetra and the psbA minicircles of Heterocapsa pygmaea. RT-PCR showed that the tRNAs were co-transcribed with the protein-coding genes that preceded them, and cleaved from the precursor before a poly(U) tail was added to the mRNA.
甲藻叶绿体基因组很独特，其基因存在于携带一到三个基因的小环状DNA分子上。此外，到目前为止，在小环上仅发现了14个典型的叶绿体定位基因，而许多基因已转移到细胞核中。我们对来自三角异帽藻的四个新小环进行了测序，其中三个携带单个蛋白质编码基因（psbD、psbE、petD），另一个似乎是“空”环。使用tRNA预测程序ARAGORN和tRNAscan-SE，在petD环中petD末端的紧下游发现了tRNA-Met，而在psbE和petD环以及三角异帽藻的几个嵌合环和矮小异帽藻的psbA小环中检测到了tRNA-Trp和tRNA-Pro。RT-PCR表明，这些tRNA与它们之前的蛋白质编码基因共同转录，并在mRNA添加聚（U）尾之前从前体中切割下来。
