Scheduled Seminars on 6/8/2010

Abhiman Saraswathi at 11:00  Edit  Reschedule  Delete

Origin and evolution of peptide-modifying dioxygenases and identification of the wybutosine hydroxylase/hydroperoxidase.
Unlike classical 2-oxoglutarate and iron-dependent dioxygenases, which include several nucleic acid modifiers, the structurally similar jumonji-related dioxygenase superfamily was only known to catalyze peptide modifications. Using comparative genomics methods, we predict that a family of jumonji-related enzymes catalyzes wybutosine hydroxylation/peroxidation at position 37 of
eukaryotic tRNAPhe. Identification of this enzyme raised questions regarding the emergence of protein- and nucleic acid-modifying activities among jumonji-related domains. We addressed these with a natural classification of DSBH domains and reconstructed the precursor of the dioxygenases as a sugar-binding domain. We identify previously under-appreciated aspects
of their active site and multiple independent innovations of 2-oxoacid-binding basic residues among these superfamilies. We show that double-stranded beta-helix dioxygenases diversified extensively in biosynthesis and modification of halogenated siderophores, antibiotics, peptide secondary metabolites and glycine-rich collagen-like proteins in bacteria.


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