Chromosome structure: DNA nucleotide sequence elements of a subset of the minichromosomes of the protozoan Trypanosoma brucei.
Chromosome structure: DNA nucleotide sequence elements of a subset of the minichromosomes of the protozoan Trypanosoma brucei.
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染色体结构：原生动物布氏锥虫微型染色体子集的 DNA 核苷酸序列元件。
DOI：
10.1128/mcb.11.8.3823-3834.1991
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发表时间：
1991
影响因子：
5.3
通讯作者：
VanderPloeg,LH
中科院分区：
文献类型：
--
作者：
Weiden,M;Osheim,YN;Beyer,AL;VanderPloeg,LH
原生动物布氏锥虫的基因组包含一组约 100 个大小约 50 至 150 kb 的微型染色体。这些染色体体积小、参与抗原变异以及有丝分裂稳定性，使它们成为原生动物染色体及其端粒结构分析的理想候选者。我们发现微型染色体的一个子集主要由简单序列 DNA 组成，微型染色体超过 90% 的长度由 177 bp 重复的串联阵列组成，表明这些分子的蛋白质编码能力有限。从端粒尖端到染色体内部位置，微型染色体的一个子集包含 GGGTTA 端粒重复序列、29 bp 端粒衍生重复序列、包含 74 bp 富含 G+C 直接重复序列的区域，该重复序列被大约 155 bp 富含 A+T 的具有弯曲特征的 DNA 隔开，以及 50 至 150 kb 的 177 bp 重复序列。一些源自微型染色体的端粒不编码蛋白质编码基因，表明端粒变异细胞表面糖蛋白基因的全部内容仅限于某些端粒。锥虫中的端粒组织与人类、酵母和疟原虫中的端粒和亚端粒组织有着惊人的相似之处。对微型染色体的电子显微镜分析表明，它们是线性分子，染色体主体没有异常结构。复制分子的结构表明，微型染色体可能具有位于染色体体中的单一双向复制起点。我们提出了锥虫微型染色体结构的模型。
The genome of the protozoanTrypanosoma bruceicontains a set of about 100 minichromosomes of about 50 to 150 kb in size. The small size of these chromosomes, their involvement in antigenic variation, and their mitotic stability make them ideal candidates for a structural analysis of protozoan chromosomes and their telomeres. We show that a subset of the minichromosomes is composed predominantly of simple-sequence DNA, with over 90% of the length of the minichromosome consisting of a tandem array of 177-bp repeats, indicating that these molecules have limited protein-coding capacity. Proceeding from the tip of the telomere to a chromosome internal position, a subset of the minichromosomes contained the GGGTTA telomere repeat, a 29-bp telomere-derived repeat, a region containing 74-bp G+C-rich direct repeats separated by approximately 155 bp of A+T-rich DNA that has a bent character, and 50 to 150 kb of the 177-bp repeat. Several of the minichromosome-derived telomeres did not encode protein-coding genes, indicating that the repertoire of telomeric variant cell surface glycoprotein genes is restricted to some telomeres only. The telomere organization in trypanosomes shares striking similarities to the organization of telomeres and subtelomeres in humans, yeasts, and plasmodia. An electron microscopic analysis of the minichromosomes showed that they are linear molecules without abnormal structures in the main body of the chromosome. The structure of replicating molecules indicated that minichromosomes probably have a single bidirectional origin of replication located in the body of the chromosome. We propose a model for the structure of the trypanosome minichromosomes.