Day John C, Goodall Tim I, Bailey Mark J
Centre for Ecology and Hydrology-Oxford, Mansfield Road, Oxford OX1 3SR, UK.
Mol Phylogenet Evol. 2009 Jan;50(1):93-101. doi: 10.1016/j.ympev.2008.09.026. Epub 2008 Oct 11.
Bioluminescence in beetles is dependent upon the enzyme luciferase. It has been hypothesised luciferase evolved from a fatty acyl-CoA synthetase gene deriving a novel bioluminescent function (neofunctionalization) after a gene duplication event. We evaluated this hypothesis within a phylogenetic framework using independent evidence obtained from the genome of Tribolium castaneum, published luciferase genes and novel luciferase and luciferase-like sequences. This phylogenetic study provides evidence for a large gene family of luciferase and luciferase-like paralogues in bioluminescent and non-bioluminescent beetles. All luciferase sequences formed a clade supporting a protoluciferase existing prior to the divergence of the Lampyridae, Elateridae and Phengodidae (Elateroidea). Multiple luciferase genes were identified from members of the Photurinae and the Luciolinae indicating complex gene duplication events within lampyrid genomes. The majority of luciferase residues were identified to be under purifying selection as opposed to positive selection. We conclude that beetle luciferase may have arisen from a process of subfunctionalization as opposed to neofunctionalization early on in the evolution of the Elateroidea.
甲虫的生物发光依赖于荧光素酶。据推测，荧光素酶是由脂肪酰辅酶A合成酶基因进化而来，在基因复制事件后获得了一种新的生物发光功能（新功能化）。我们利用从赤拟谷盗基因组、已发表的荧光素酶基因以及新的荧光素酶和类荧光素酶序列中获得的独立证据，在系统发育框架内评估了这一假设。这项系统发育研究为生物发光和非生物发光甲虫中荧光素酶和类荧光素酶旁系同源物的一个大基因家族提供了证据。所有荧光素酶序列形成了一个分支，支持在萤科、叩头虫科和光萤科（叩头虫总科）分化之前就存在的原始荧光素酶。从光萤亚科和熠萤亚科的成员中鉴定出多个荧光素酶基因，这表明萤科基因组内发生了复杂的基因复制事件。与正选择相反，大多数荧光素酶残基被鉴定为受到纯化选择。我们得出结论，甲虫荧光素酶可能是由亚功能化过程产生的，而不是在叩头虫总科进化早期由新功能化产生的。
