6ici
From Proteopedia
Crystal structure of human MICAL3
Structural highlights
FunctionMICA3_HUMAN Monooxygenase that promotes depolymerization of F-actin by mediating oxidation of specific methionine residues on actin. Acts by modifying actin subunits through the addition of oxygen to form methionine-sulfoxide, leading to promote actin filament severing and prevent repolymerization (By similarity). Involved in exocytic vesicles tethering and fusion: the monooxygenase activity is required for this process.[1] Publication Abstract from PubMedMICAL is an oxidoreductase that participates in cytoskeleton reorganization via actin disassembly in the presence of NADPH. Although three MICALs (MICAL1, MICAL2 and MICAL3) have been identified in mammals, only the structure of mouse MICAL1 has been reported. Here, the first crystal structure of human MICAL3, which contains the flavin-containing monooxygenase (FMO) and calponin-homology (CH) domains, is reported. MICAL3 has an FAD/NADP-binding Rossmann-fold domain for mono-oxygenase activity like MICAL1. The FMO and CH domains of both MICAL3 and MICAL1 are highly similar in structure, but superimposition of the two structures shows a different relative position of the CH domain in the asymmetric unit. Based on kinetic analyses, the catalytic efficiency of MICAL3 dramatically increased on adding F-actin only when the CH domain was available. However, this did not occur when two residues, Glu213 and Arg530, were mutated in the FMO and CH domains, respectively. Overall, MICAL3 is structurally highly similar to MICAL1, which suggests that they may adopt the same catalytic mechanism, but the difference in the relative position of the CH domain produces a difference in F-actin substrate specificity. Structural and kinetic insights into flavin-containing monooxygenase and calponin-homology domains in human MICAL3.,Kim J, Lee H, Roh YJ, Kim HU, Shin D, Kim S, Son J, Lee A, Kim M, Park J, Hwang SY, Kim K, Lee YK, Jung HS, Hwang KY, Lee BC IUCrJ. 2020 Jan 1;7(Pt 1):90-99. doi: 10.1107/S2052252519015409. eCollection 2020, Jan 1. PMID:31949908[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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