title: Repurposing TRASH: emergence of the enzyme organomercurial lyase from a non-catalytic zinc finger scaffold.
abstract: The mercury resistance pathway enzyme organomercurial lyase (MerB) catalyzes the conversion of organomercurials to ionic mercury (Hg(2+)). Here, we provide evidence for the emergence of this enzyme from a TRASH-like, non-enzymatic, treble-clef zinc finger ancestor by domain duplication and fusion. Surprisingly, the structure-stabilizing metal-binding core of the treble-clef appears to have been repurposed in evolution to serve a catalytic role. Novel enzymatic functions are believed to have evolved from ancestral generalist catalytic scaffolds or from already specialized enzymes with catalytic promiscuity. The emergence of MerB from a zinc finger ancestor serves as a rare example of how a novel enzyme may emerge from a non-catalytic scaffold with a related binding function.
authors.affiliation: CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh, India.
authors.forename: Gurmeet
authors.initials: G
authors.lastname: Kaur
authors.affiliation: CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh, India. Electronic address: krishna@imtech.res.in.
authors.forename: Srikrishna
authors.initials: S
authors.lastname: Subramanian
mesh_terms: D000596:Amino Acids / Q000737:chemistry / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D002384:Catalysis; D019295:Computational Biology; D004798:Enzymes / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D019143:Evolution, Molecular; D020440:Gene Duplication; D008190:Lyases / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D008628:Mercury / Q000633:toxicity; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D016335:Zinc Fingers / Q000235:genetics
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D004798:Enzymes; D008190:Lyases; C097247:MerB protein, Bacteria; D008628:Mercury
keywords: Domain duplication; Domain fusion; Enzyme evolution; MerA; MerH; NosL; Promiscuous enzymes