概括
对人体免疫球蛋白卡帕轻链可变区域 (V卡帕基因) 的基因分析揭示了等位基因变异和基因重复事件. 一个集群的替代模式表明基因转换可能已经发生,影响蛋白质结构.
科学领域:
- 免疫遗传学 免疫遗传学
- 分子生物学分子生物学
- 人类遗传学 人类遗传学
背景情况:
- 人类免疫球蛋白卡帕轻链 (V kappa) 基因家族编码了适应性免疫系统的关键组成部分.
- 了解V kappa基因结构和进化对于破译抗体多样性和功能至关重要.
研究的目的:
- 分析人类V卡帕基因内的序列变异和结构关系.
- 研究塑造V kappa基因多样性的进化机制,包括基因重复和基因转换.
主要方法:
- 密切相关的人类V kappa基因的DNA测序.
- 对比序列分析以确定核酸替代和同质性块.
- 生物信息分析以推断进化事件,如基因重复和基因转换.
主要成果:
- 确定了两种非常相似的V kappa基因,可能是HK 101位元的等位基因,因单个核酸替代而有所不同.
- 这种替代导致卡帕链第一个互补性决定区域 (CDR1) 中的氨基酸变化.
- 在13.5kb区域内发现非基V卡帕位点 (HK 101和HK 137) 之间显著的序列同质性,这表明最近的基因重复.
- 观察到非基V卡帕基因的39个基段内异常的替代聚类,跨越CDR1和第二个框架区域 (FR2).
结论:
- 序列数据支持了人类V kappa基因家族最近基因重复事件的假设.
- 聚类核酸替代强烈表明基因转换事件,其中一个V kappa基因的片段被另一个同源片段替换.
- 这些发现提供了对动态进化过程的见解,这些过程有助于产生抗体多样性.
相关概念视频
Genome Size and the Evolution of New Genes
While every living organism has a genome of some kind (be it RNA, or DNA), there is considerable variation in the sizes of these blueprints. One major factor that impacts genome size is whether the organism is prokaryotic or eukaryotic. In prokaryotes, the genome contains little to no non-coding sequence, such that genes are tightly clustered in groups or operons sequentially along the chromosome. Conversely, the genes in eukaryotes are punctuated by long stretches of non-coding sequence.
Gene Families
Gene families consist of groups of genes proposed to have originated from a common ancestor. Typically these arise through events in which a gene or genes are mistakenly duplicated during cell division. Unlike their parent genes (which are subject to selection pressure to maintain function), these gene copies do not need to preserve their sequences and may evolve at a relatively faster rate.
Occasionally these regions can be adapted to take on new roles within the organism, becoming novel genes...
Occasionally these regions can be adapted to take on new roles within the organism, becoming novel genes...
Gene Duplication and Divergence
The seminal work of Ohno in 1970 popularized the idea of gene duplication and divergence. DNA sequence comparison studies reveal that a large portion of the genes in bacteria, archaebacteria, and eukaryotes was generated by gene duplication and divergence, indicating its critical role in evolution.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.
Exon Recombination
The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new gene formation. It is observed across vertebrates, invertebrates, and in some plants such as potatoes and sunflowers. During exon recombination, exons from the same or different genes recombine and produce new exon-intron combinations, which might evolve into new genes.
Exon shuffling follows “splice frame rules.” Each exon has three reading...
Exon shuffling follows “splice frame rules.” Each exon has three reading...
Genome Size and the Evolution of New Genes
While every living organism has a genome of some kind (be it RNA, or DNA), there is considerable variation in the sizes of these blueprints. One major factor that impacts genome size is whether the organism is prokaryotic or eukaryotic. In prokaryotes, the genome contains little to no non-coding sequence, such that genes are tightly clustered in groups or operons sequentially along the chromosome. Conversely, the genes in eukaryotes are punctuated by long stretches of non-coding sequence.
Gene Conversion
Other than maintaining genome stability via DNA repair, homologous recombination plays an important role in diversifying the genome. In fact, the recombination of sequences forms the molecular basis of genomic evolution. Random and non-random permutations of genomic sequences create a library of new amalgamated sequences. These newly formed genomes can determine the fitness and survival of cells. In bacteria, homologous and non-homologous types of recombination lead to the evolution of new...


