Homologous recombination in the tandem calmodulin genes of Trypanosoma brucei yields multiple products: compensation for deleterious deletions by gene amplification.
Homologous recombination in the tandem calmodulin genes of Trypanosoma brucei yields multiple products: compensation for deleterious deletions by gene amplification.
复制标题
布氏锥虫串联钙调蛋白基因的同源重组产生多种产物：通过基因扩增补偿有害缺失。
DOI：
10.1101/gad.5.11.2024
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发表时间：
1991
影响因子：
10.5
通讯作者：
Sollner-Webb,B
中科院分区：
文献类型：
--
作者：
Eid,JE;Sollner-Webb,B
钙调素-新霉素抗性融合基因与布鲁氏锥虫染色体之间的同源重组不仅发生在钙调素位点的5‘和3’侧大片段上，而且发生在四个串联基因组钙调素基因中的任何一个基因上。这导致一个由嵌合的新基因和四个、三个、两个、一个或零功能钙调蛋白基因组成的重组位点。发生后一种情况的细胞只有正常数量的一半完整的钙调素基因，并伴有生长缓慢的表型。经过几个月的繁殖，这些品系获得额外的钙调素基因，通常是通过在非目标位点扩增钙调素基因，并同时恢复到正常的生长速度。这种反应可能与锥虫在串联染色体阵列中维持大多数管家基因的特性有关。重组似乎是由转染质粒的线性化端与宿主基因组中的同源区域之间的交叉事件启动的；第二次交叉一般发生在内部，在该区域同源性不超过87bp。
Homologous recombination between a calmodulin-neomycin-resistance fusion gene and the Trypanosoma brucei chromosome takes place not only in the large 5'- and 3'-flanking segments of the calmodulin locus but also in any of the four tandem genomic calmodulin genes. This results in a recombined locus consisting of the chimeric neor gene and four, three, two, one, or zero functional calmodulin genes. Cells bearing this latter event have half of their normal number of intact calmodulin genes and an accompanying phenotype of slow growth. Over months of propagation, these lines acquire additional calmodulin genes, frequently by amplifying a calmodulin gene at the untargeted locus, and concomitantly revert to normal growth rate. This response could be related to the property of the trypanosome of maintaining most housekeeping genes in tandem chromosomal arrays. Recombination appears to be initiated by a crossover event between the linearized end of the transfecting plasmid and a homologous region in the host genome; the second crossover generally occurs internally and in that region requires no more than 87 bp of homology.