6twk

Substrate bound structure of the Ectoine utilization protein EutD (DoeA) from Halomonas elongata

spinqualitylabelsall models 6twk, resolution 2.25Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6twk is a 2 chain structure with sequence from Halomonas elongata. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.25Å Ligands: 4CS, P4B Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function DOEA_HALED Publication Abstract from PubMed When faced with increased osmolarity in the environment, many bacterial cells accumulate the compatible solute ectoine and its derivative 5-hydroxyectoine. Both compounds are not only potent osmostress protectants, but also serve as effective chemical chaperones stabilizing protein functionality. Ectoines are energy-rich nitrogen and carbon sources that have an ecological impact that shapes microbial communities. Although the biochemistry of ectoine and 5-hydroxyectoine biosynthesis is well understood, our understanding of their catabolism is only rudimentary. Here, we combined biochemical and structural approaches to unravel the core of ectoine and 5-hydroxyectoine catabolisms. We show that a conserved enzyme bimodule consisting of the EutD ectoine/5-hydroxyectoine hydrolase and the EutE deacetylase degrades both ectoines. We determined the high-resolution crystal structures of both enzymes, derived from the salt-tolerant bacteria Ruegeria pomeroyi and Halomonas elongata. These structures, either in their apo-forms or in forms capturing substrates or intermediates, provided detailed insights into the catalytic cores of the EutD and EutE enzymes. The combined biochemical and structural results indicate that the EutD homodimer opens the pyrimidine ring of ectoine through an unusual covalent intermediate, N-alpha-2 acetyl-L-2,4-diaminobutyrate (alpha-ADABA). We found that alpha-ADABA is then deacetylated by the zinc-dependent EutE monomer into diaminobutyric acid (DABA), which is further catabolized to L-aspartate. We observed that the EutD-EutE bimodule synthesizes exclusively the alpha-, but not the gamma-isomers of ADABA or hydroxy-ADABA. Of note, alpha-ADABA is known to induce the MocR/GabR-type repressor EnuR, which controls the expression of many ectoine catabolic genes clusters. We conclude that hydroxy-alpha-ADABA might serve a similar function. Degradation of the microbial stress protectants and chemical chaperones ectoine and hydroxyectoine by a bacterial hydrolase-deacetylase complex.,Mais CN, Hermann L, Altegoer F, Seubert A, Richter AA, Wernersbach I, Czech L, Bremer E, Bange G J Biol Chem. 2020 May 13. pii: RA120.012722. doi: 10.1074/jbc.RA120.012722. PMID:32404365 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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