The Genome of the African Trypanosome
The Genome of the African Trypanosome
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DOI：
10.1007/0-306-46894-8_11
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发表时间：
2002
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影响因子：
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通讯作者：
J. Donelson
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文献类型：
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作者：
J. Donelson
布鲁氏锥虫是一种二倍体生物，核单倍体DNA含量为35±9兆碱基对(Mb)，取决于锥虫的分离株。大约15%的细胞DNA存在于动叶绿体中，它被组织成均一的23kb的大环和异质的1kb的小环。其余85%的DNA以大小从50kb到6Mb的线性DNA分子存在于细胞核中。至少存在11对1-6Mb的百万碱基染色体，从小到大编号为I-XI。一个百万碱基染色体对的两个同源物在大小上可能相差多达4倍。还发现了几条中等大小的染色体，大小为0.2-0.9Mb，倍性不确定。巨型数据库和中间染色体的端粒与编码变异表面糖蛋白(VSG)的基因的表达部位相连。此外，约有100个50-150kb的线性微小染色体存在，作为未表达的端粒连接的VSG基因的储存库。约50%的核基因组是编码序列。到目前为止，只发现了一个tRNA基因和一个蛋白质编码基因，它们是特定的聚(A)聚合酶，包含一个内含子。染色体I和II(每个约1Mb)的全序列测定已接近完成，已经产生了超过20Mb的不连续的单程基因组DNA序列数据。根据与Leishmaniagenome的类比，非洲锥虫核基因组的大部分很可能是由50个或更多无内含子基因组成的长转录单位。对这种基因组序列及其全套基因的了解将为确定控制或消除这种病原体及其致命疾病的更好方法开辟许多新的途径。
Trypanosoma bruceiis a diploid organism with a nuclear haploid DNA content of 35 ± 9 megabase pairs (Mb) depending on the trypanosome isolate. About 15% of the total cellular DNA is in the kinetoplast where it is organized as homogenous 23-kb maxicircles and heterogeneous 1 -kb minicircles. The remaining 85% of the DNA occurs in the nucleus as linear DNA molecules ranging in size from 50 kb to 6 Mb. At least 11 pairs of megabase chromosomes of 1 to 6 Mb exist that are numbered I-XI from smallest to largest. The two homologues of a megabase chromosome pair can differ in size by as much as 4-fold. Several intermediate-sized chromosomes of 0.2 – 0.9 Mb and uncertain ploidy are also present. The telomeres of the megabase and intermediate chromosomes are linked to expression sites for the genes encoding the variant surface glycoproteins (VSGs). In addition, about 100 linear minichromosomes of 50–150 kb occur and serve as repositories for unexpressed, telomere-linked VSG genes. About 50% of the nuclear genome is coding sequence. To date only one tRNA gene and one protein-encoding gene, specifying poly(A) polymerase, have been found to contain an intron. The complete sequence determination of chromosomes I and II (about 1 Mb each) is nearing completion and more than 20 Mb of discontinuous single-pass genomic DNA sequence data have been generated. Based on analogy with theLeishmaniagenome, much of the African trypanosome nuclear genome is likely to be arrayed as long transcription units of 50 or more intronless genes. Knowledge of this genomic sequence and its complete set of genes will open many new avenues for identifying better ways to control or eliminate this pathogen and its deadly disease.