Enzyme annotations often suffer from incomplete functional information for homologous sequences. Extrapolation from one characterized enzyme to multiple possible substrate-enzyme pairs, using bioinformatics and experimental approaches, leads to four distinct β-keto acid cleavage enzyme functional motifs and assignment of 14 new activities. Millions of protein database entries are not assigned reliable functions, preventing the full understanding of chemical diversity in living organisms. Here, we describe an integrated strategy for the discovery of various enzymatic activities catalyzed within protein families of unknown or little known function. This approach relies on the definition of a generic reaction conserved within the family, high-throughput enzymatic screening on representatives, structural and modeling investigations and analysis of genomic and metabolic context. As a proof of principle, we investigated the DUF849 Pfam family and unearthed 14 potential new enzymatic activities, leading to the designation of these proteins as β-keto acid cleavage enzymes. We propose an in vivo role for four enzymatic activities and suggest key residues for guiding further functional annotation. Our results show that the functional diversity within a family may be largely underestimated. The extension of this strategy to other families will improve our knowledge of the enzymatic landscape.
酶注释通常会因同源序列的功能信息不完整而受到影响。利用
生物信息学和实验方法,从一种已知的酶推断出多种可能的底物-酶对,从而发现了四种不同的β-
酮酸裂解酶功能基序,并确定了14种新酶的活性。数百万条蛋白质数据库条目没有可靠的酶功能,这阻碍了对
生物体
化学多样性的全面理解。在此,我们描述了一种综合策略,用于发现未知或鲜为人知的蛋白质家族中催化各种酶活性的酶。该方法依赖于定义家族中保守的通用反应,对代表性酶进行高通量筛选,进行结构和建模研究,以及分析
基因组和代谢背景。作为原理验证,我们研究了DUF849 Pfam家族,并发现了14种潜在的新酶活性,从而将这些蛋白质指定为β-
酮酸裂解酶。我们提出了四种酶活性的体内作用,并提出了关键残基,以指导进一步的功能注释。我们的结果表明,一个家族内的功能多样性可能被大大低估了。将这一策略扩展到其他家族将提高我们对酶谱的认识。