Foerstner Konrad U, Doerks Tobias, Muller Jean, Raes Jeroen, Bork Peer
European Molecular Biology Laboratory, Heidelberg, Germany.
PLoS One. 2008;3(12):e3976. doi: 10.1371/journal.pone.0003976. Epub 2008 Dec 19.
Bacterial nitrile hydratase (NHases) are important industrial catalysts and waste water remediation tools. In a global computational screening of conventional and metagenomic sequence data for NHases, we detected the two usually separated NHase subunits fused in one protein of the choanoflagellate Monosiga brevicollis, a recently sequenced unicellular model organism from the closest sister group of Metazoa. This is the first time that an NHase is found in eukaryotes and the first time it is observed as a fusion protein. The presence of an intron, subunit fusion and expressed sequence tags covering parts of the gene exclude contamination and suggest a functional gene. Phylogenetic analyses and genomic context imply a probable ancient horizontal gene transfer (HGT) from proteobacteria. The newly discovered NHase might open biotechnological routes due to its unconventional structure, its new type of host and its apparent integration into eukaryotic protein networks.
细菌腈水合酶（NHases）是重要的工业催化剂和废水修复工具。在对常规和宏基因组序列数据进行的全球范围内的NHases计算筛选中，我们在领鞭毛虫短柄单歧藻（Monosiga brevicollis）的一种蛋白质中检测到两个通常分离的NHase亚基融合在一起，短柄单歧藻是一种最近测序的单细胞模式生物，来自后生动物最亲近的姐妹群。这是首次在真核生物中发现NHase，也是首次观察到它作为一种融合蛋白。内含子的存在、亚基融合以及覆盖该基因部分区域的表达序列标签排除了污染的可能性，并表明这是一个功能基因。系统发育分析和基因组背景暗示其可能是从变形菌进行了古老的水平基因转移（HGT）。新发现的NHase因其非常规结构、新型宿主以及明显整合到真核蛋白质网络中，可能会开辟生物技术路线。
