Gomes Ana C, Miranda Isabel, Silva Raquel M, Moura Gabriela R, Thomas Benjamin, Akoulitchev Alexandre, Santos Manuel A S
CESAM & Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal.
Genome Biol. 2007;8(10):R206. doi: 10.1186/gb-2007-8-10-r206.
Genetic code alterations have been reported in mitochondrial, prokaryotic, and eukaryotic cytoplasmic translation systems, but their evolution and how organisms cope and survive such dramatic genetic events are not understood.
Here we used an unusual decoding of leucine CUG codons as serine in the main human fungal pathogen Candida albicans to elucidate the global impact of genetic code alterations on the proteome. We show that C. albicans decodes CUG codons ambiguously and tolerates partial reversion of their identity from serine back to leucine on a genome-wide scale.
Such codon ambiguity expands the proteome of this human pathogen exponentially and is used to generate important phenotypic diversity. This study highlights novel features of C. albicans biology and unanticipated roles for codon ambiguity in the evolution of the genetic code.
线粒体、原核生物和真核生物细胞质翻译系统中均已报道了遗传密码改变的情况，但人们并不了解它们的进化过程以及生物体如何应对和在如此剧烈的遗传事件中存活下来。
在此，我们利用在主要的人类真菌病原体白色念珠菌中亮氨酸CUG密码子被异常解码为丝氨酸这一现象，来阐明遗传密码改变对蛋白质组的全局影响。我们表明，白色念珠菌对CUG密码子的解码具有模糊性，并且在全基因组范围内容忍其身份从丝氨酸部分逆转回亮氨酸。
这种密码子模糊性使这种人类病原体的蛋白质组呈指数级扩展，并被用于产生重要的表型多样性。这项研究突出了白色念珠菌生物学的新特征以及密码子模糊性在遗传密码进化中出人意料的作用。
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