Structure of galactarate dehydratase, a new fold in an enolase involved in bacterial fitness after antibiotic treatment

Monica Rosas-Lemus, George Minasov, Ludmilla Shuvalova, Zdzislaw Wawrzak, Olga Kiryukhina, Nathan Mih, Lukasz Jaroszewski, Bernhard Palsson, Adam Godzik, Karla J.F. Satchell*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Galactarate dehydratase (GarD) is the first enzyme in the galactarate/glucarate pathway and catalyzes the dehydration of galactarate to 3-keto-5-dehydroxygalactarate. This protein is known to increase colonization fitness of intestinal pathogens in antibiotic-treated mice and to promote bacterial survival during stress. The galactarate/glucarate pathway is widespread in bacteria, but not in humans, and thus could be a target to develop new inhibitors for use in combination therapy to combat antibiotic resistance. The structure of almost all the enzymes of the galactarate/glucarate pathway were solved previously, except for GarD, for which only the structure of the N-terminal domain was determined previously. Herein, we report the first crystal structure of full-length GarD solved using a seleno-methoionine derivative revealing a new protein fold. The protein consists of three domains, each presenting a novel twist as compared to their distant homologs. GarD in the crystal structure forms dimers and each monomer consists of three domains. The N-terminal domain is comprised of a β-clip fold, connected to the second domain by a long unstructured linker. The second domain serves as a dimerization interface between two monomers. The C-terminal domain forms an unusual variant of a Rossmann fold with a crossover and is built around a seven-stranded parallel β-sheet supported by nine α-helices. A metal binding site in the C-terminal domain is occupied by Ca2+. The activity of GarD was corroborated by the production of 5-keto-4-deoxy-D-glucarate under reducing conditions and in the presence of iron. Thus, GarD is an unusual enolase with a novel protein fold never previously seen in this class of enzymes.

Original languageEnglish (US)
Pages (from-to)711-722
Number of pages12
JournalProtein Science
Volume29
Issue number3
DOIs
StatePublished - Mar 1 2020

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Keywords

  • Escherichia coli
  • antibiotic treatment
  • bacterial fitness
  • enolase
  • galactarate dehydratase
  • intestinal pathogens
  • novel fold

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology

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