Crystal structural analysis and characterization for MlrC enzyme of Sphingomonas sp. ACM-3962 involved in linearized microcystin degradation

Guo, Xiaoliang; Jiang, Qinqin; Li, Zengru; Cheng, Cai; Feng, Yu; He, Yanlin; Zuo, Lingzi; Ding, Wei; Zhang, Delin; Feng, Lingling

doi:10.1016/j.chemosphere.2023.137866

Cited by 4 publications

(1 citation statement)

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“…Heterologously expressed enzymes can be used not only to study their own functions and properties, but also to investigate biochemical pathways and molecular mechanisms ( Zhang Z. et al, 2020 ). Mechanism of catalysis of enzyme A and enzyme C were studied in depth, and the crystal structure of enzyme C was analyzed to clarify its structure and function ( Guo et al, 2023 ). However, information about MlrB is limited.…”

Section: Introductionmentioning

confidence: 99%

Enzymatic mechanism of MlrB for catalyzing linearized microcystins by Sphingopyxis sp. USTB-05

Teng,

Xu,

Zhang

et al. 2024

Front. Microbiol.

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Microcystins (MCs) are the most widespread cyanobacterial toxins in eutrophic water body. As high toxic intermediate metabolites, linearized MCs are further catalyzed by linearized microcystinase (MlrB) of Sphingopyxis sp. USTB-05. Here MlrB structure was studied by comprizing with a model representative of the penicillin-recognizing enzyme family via homology modeling. The key active sites of MlrB were predicted by molecular docking, and further verified by site-directed mutagenesis. A comprehensive enzymatic mechanism for linearized MCs biodegradation by MlrB was proposed: S77 transferred a proton to H307 to promote a nucleophilic attack on the peptide bond (Ala-Leu in MC-LR or Ala-Arg in MC-RR) of linearized MCs to form the amide intermediate. Then water was involved to break the peptide bond and produced the tetrapeptide as product. Meanwhile, four amino acid residues (K80, Y171, N173 and D245) acted synergistically to stabilize the substrate and intermediate transition states. This study firstly revealed the enzymatic mechanism of MlrB for biodegrading linearized MCs with both computer simulation and experimental verification.

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Section: Introductionmentioning

confidence: 99%