Nelson David R
Dept. of Molecular Sciences, University of Tennessee Health Science Center, 858 Madison Ave., Suite G01, Memphis, TN 38163, USA.
Biochim Biophys Acta. 2011 Jan;1814(1):14-8. doi: 10.1016/j.bbapap.2010.08.008. Epub 2010 Aug 21.
The state of cytochrome P450 sequence accumulation in different phyla is summarized. 12,456 P450s are currently named, with about 6000 more that are known, but not yet named. As the number of genomes sequenced moves from a few dozen to an inevitable few thousand, issues of nomenclature are discussed. Orthology will be the guiding principle for naming across related genomes such as vertebrates. Even if 1000 vertebrate genomes are sequenced there will still be only 19 CYP families in vertebrates. The variable clusters of genes in families CYP2, CYP3 and CYP4 may pose challenges for naming as 1:1 orthologs do not necessarily exist. The value of synteny across genomes is emphasized as a tool for deep time evolutionary studies of P450s in animals. There is evidence that macrosynteny may be useful in tracing the origin of animal CYP clans. The concept of saturation of sequence space is described and used to estimate how complete our knowledge is of P450s in different phyla. The special niche of filamentous fungal P450s acting in secondary metabolite gene clusters is discussed. From one quarter to one third of P450s in these fungi may be dedicated to these roles.
总结了不同门类中细胞色素P450序列积累的状况。目前已命名的P450有12,456种，还有约6000种已知但尚未命名。随着测序基因组数量从几十种增加到必然会达到的几千种，讨论了命名问题。直系同源性将作为跨相关基因组（如脊椎动物）命名的指导原则。即使对1000个脊椎动物基因组进行测序，脊椎动物中仍只会有19个CYP家族。CYP2、CYP3和CYP4家族中可变的基因簇可能给命名带来挑战，因为不一定存在1:1的直系同源物。强调了基因组间共线性作为动物P450深度进化研究工具的价值。有证据表明，宏观共线性可能有助于追溯动物CYP家族的起源。描述了序列空间饱和度的概念，并用于估计我们对不同门类中P450的了解有多完整。讨论了丝状真菌P450在次生代谢物基因簇中的特殊作用。这些真菌中四分之一到三分之一的P450可能专门负责这些功能。
