Evidence
Protein Sci. 2023 Aug 13:e4751. doi: 10.1002/pro.4751. Online ahead of print.
ABSTRACT
Haloalkane dehalogenase (HLD) enzymes employ an SN 2 nucleophilic substitution mechanism to erase halogen substituents in diverse organohalogen compounds. Subfamily I and II HLDs are well-characterized enzymes, but a mode and purpose of multimerization of subfamily III HLDs are unknown. Here we probe the structural organization of DhmeA, a subfamily III HLD-like enzyme from the archaeon Haloferax mediterranei, by combining cryo-electron microscopy (cryo-EM) and X-ray crystallography. We show that full-length wild-type DhmeA forms diverse quaternary structures, ranging from small oligomers to large supramolecular ring-like assemblies of various sizes and symmetries. We optimized sample preparation steps, enabling three-dimensional reconstructions of an oligomeric species by single-particle cryo-EM. Moreover, we engineered a crystallizable mutant (DhmeAΔGG ) that provided diffraction-quality crystals. The 3.3 Å crystal structure reveals that DhmeAΔGG forms a ring-like 20-mer structure with outer and inner diameter of ~200 Å and ~80 Å, respectively. An enzyme homodimer represents a basic repeating building unit of the crystallographic ring. Three assembly interfaces (dimerization, tetramerization and multimerization) were identified to form the supramolecular ring that displays a negatively charged exterior, while its interior part harboring catalytic sites is positively charged. Localization and exposure of catalytic machineries suggest a possible processing of large negatively charged macromolecular substrates. This article is protected by copyright. All rights reserved.
PMID:37574754 | DOI:10.1002/pro.4751
Add to Google Keep
Estimated reading time: 4 minute(s)
Latest: Psychiatryai.com #RAISR4D
Real-Time Evidence Search [Psychiatry]
AI Search [Andisearch.com]
AI Q/A [Aikko.com]
Multimeric structure of a subfamily III haloalkane dehalogenase-like enzyme solved by combination of cryo-EM and X-ray crystallography
🌐 90 Days
Evidence Blueprint
Multimeric structure of a subfamily III haloalkane dehalogenase-like enzyme solved by combination of cryo-EM and X-ray crystallography
☊ AI-Driven Related Evidence Nodes
(recent articles with at least 5 words in title)
Save Evidence Blueprint
Save as PDF