Overexpression of Molecular Chaperone Genes in Nucleomorph Genomes
Overexpression of Molecular Chaperone Genes in Nucleomorph Genomes
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DOI：
10.1093/molbev/msu092
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发表时间：
2014-06-01
影响因子：
10.7
通讯作者：
Ishida, Ken-ichiro
中科院分区：
文献类型：
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作者：
Hirakawa, Yoshihisa;Suzuki, Shigekatsu;Ishida, Ken-ichiro
绿藻植物和隐植物拥有复杂的质体，这些质体分别是通过摄入绿藻和红藻内共生体而获得的。质体被四层膜包围，并且称为核形态的残余核保留在质体周室中，对应于内共生体的残余细胞质。核形体的基因组大大减少，仅拥有数百个具有高进化率的基因。我们使用 RNA-seq 转录组方法检查了两种绿蛛植物和三种隐植物的核形态基因组编码的所有蛋白质基因的相对转录水平。两种热休克蛋白Hsp70和Hsp90的基因在正常条件下高表达。研究表明，分子伴侣过度表达会导致细菌中基因突变的积累。我们的结果表明，核型基因组中热休克蛋白的过度表达可能在缓冲蛋白质突变不稳定方面发挥作用，这可能允许核型编码蛋白质的高进化率。
Chlorarachniophytes and cryptophytes possess complex plastids that were acquired by the ingestion of a green and red algal endosymbiont, respectively. The plastids are surrounded by four membranes, and a relict nucleus, called the nucleomorph, remains in the periplastidal compartment, which corresponds to the remnant cytoplasm of the endosymbiont. Nucleomorphs contain a greatly reduced genome that possesses only several hundred genes with high evolutionary rates. We examined the relative transcription levels of the genes of all proteins encoded by the nucleomorph genomes of two chlorarachniophytes and three cryptophytes using an RNA-seq transcriptomic approach. The genes of two heat shock proteins, Hsp70 and Hsp90, were highly expressed under normal conditions. It has been shown that molecular chaperone overexpression allows an accumulation of genetic mutations in bacteria. Our results suggest that overexpression of heat shock proteins in nucleomorph genomes may play a role in buffering the mutational destabilization of proteins, which might allow the high evolutionary rates of nucleomorph-encoded proteins.