Structure and function of Caulobacter crescentus aldose-aldose oxidoreductase

Helena Taberman, Martina Andberg, Anu Koivula, Nina Hakulinen, Merja Penttilä, Juha Rouvinen, Tarja Parkkinen*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Aldose-aldose oxidoreductase (Cc AAOR) is a recently characterized enzyme from the bacterial strain Caulobacter crescentus CB15 belonging to the glucose-fructose oxidoreductase/inositol dehydrogenase/rhizopine catabolism protein (Gfo/Idh/MocA) family. Cc AAOR catalyses the oxidation and reduction of a panel of aldose monosaccharides using a tightly bound NADP(H) cofactor that is regenerated in the catalytic cycle. Furthermore, Cc AAOR can also oxidize 1,4-linked oligosaccharides. In the present study, we present novel crystal structures of the dimeric Cc AAOR in complex with the cofactor and glycerol, D-xylose, D-glucose, maltotriose and D-sorbitol determined to resolutions of 2.0, 1.8, 1.7, 1.9 and 1.8 angstrom(1 angstrom = 0.1 nm), respectively. These complex structures allowed for a detailed analysis of the ligandbinding interactions. The structures showed that the C1 carbon of a substrate, which is either reduced or oxidized, is close to the reactive C4 carbon of the nicotinamide ring of NADP(H). In addition, the O1 hydroxy group of the substrate, which is either protonated or deprotonated, is unexpectedly close to both Lys104 and Tyr189, which may both act as a proton donor or acceptor. This led us to hypothesize that this intriguing feature could be beneficial for Cc AAOR to catalyse the reduction of a linear form of a monosaccharide substrate and the oxidation of a pyranose form of the same substrate in a reaction cycle, during which the bound cofactor is regenerated.

Original languageEnglish
Pages (from-to)297-307
Number of pages11
JournalBIOCHEMICAL JOURNAL
Volume472
DOIs
Publication statusPublished - 15 Dec 2015
MoE publication typeA1 Journal article-refereed

Keywords

  • carbohydrate
  • crystal structure
  • enzyme mechanism
  • glucose-fructose oxidoreductase/inositol dehydrogenase/rhizopine catabolism protein (Gfo/Idh/MocA) family
  • oxidoreductase
  • reduced nicotinamide-adenine dinucleotide phosphate [NADP(H)] cofactor
  • GLUCOSE-FRUCTOSE OXIDOREDUCTASE
  • ZYMOMONAS-MOBILIS
  • MACROMOLECULAR CRYSTALLOGRAPHY
  • STRUCTURE REFINEMENT
  • CRYSTALS
  • PROTEINS
  • PHENIX
  • ESRF

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