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J Biol Chem. 2015 Oct 23;290(43):26249-58. doi: 10.1074/jbc.M115.673459. Epub 2015 Aug 3.

Structural Characterization of CalS8, a TDP-α-D-Glucose Dehydrogenase Involved in Calicheamicin Aminodideoxypentose Biosynthesis.

Author information

1
From the Center for Pharmaceutical Research and Innovation, University of Kentucky College of Pharmacy, Lexington, Kentucky 40536-0596.
2
the Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, Illinois 60439.
3
the School of Pharmacy, University of Maryland Eastern Shore, Princess Anne, Maryland 21853.
4
the Department of BioSciences, Department of Chemistry, Rice University, Houston, Texas 77005.
5
the Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, and.
6
From the Center for Pharmaceutical Research and Innovation, University of Kentucky College of Pharmacy, Lexington, Kentucky 40536-0596, jsthorson@uky.edu.
7
the Department of BioSciences, Department of Chemistry, Rice University, Houston, Texas 77005 the Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, and georgep@rice.edu.

Abstract

Classical UDP-glucose 6-dehydrogenases (UGDHs; EC 1.1.1.22) catalyze the conversion of UDP-α-d-glucose (UDP-Glc) to the key metabolic precursor UDP-α-d-glucuronic acid (UDP-GlcA) and display specificity for UDP-Glc. The fundamental biochemical and structural study of the UGDH homolog CalS8 encoded by the calicheamicin biosynthetic gene is reported and represents one of the first studies of a UGDH homolog involved in secondary metabolism. The corresponding biochemical characterization of CalS8 reveals CalS8 as one of the first characterized base-permissive UGDH homologs with a >15-fold preference for TDP-Glc over UDP-Glc. The corresponding structure elucidations of apo-CalS8 and the CalS8·substrate·cofactor ternary complex (at 2.47 and 1.95 Å resolution, respectively) highlight a notably high degree of conservation between CalS8 and classical UGDHs where structural divergence within the intersubunit loop structure likely contributes to the CalS8 base permissivity. As such, this study begins to provide a putative blueprint for base specificity among sugar nucleotide-dependent dehydrogenases and, in conjunction with prior studies on the base specificity of the calicheamicin aminopentosyltransferase CalG4, provides growing support for the calicheamicin aminopentose pathway as a TDP-sugar-dependent process.

KEYWORDS:

UDP-glucose dehydrogenase (UGDH); biosynthesis; calicheamicin; carbohydrate; crystal structure; dehydrogenase; deoxysugar; enediyne; natural product; sugar nucleotide

PMID:
26240141
PMCID:
PMC4646273
DOI:
10.1074/jbc.M115.673459
[Indexed for MEDLINE]
Free PMC Article

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