4txi
Construct of MICAL-1 containing the monooxygenase and calponin homology domains
Structural highlights
FunctionMICA1_MOUSE 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. Acts as a cytoskeletal regulator that connects NEDD9 to intermediate filaments (By similarity). Also acts as a negative regulator of apoptosis via its interaction with STK38 and STK38L; acts by antagonizing STK38 and STK38L activation by MST1/STK4. Publication Abstract from PubMedMICALs (Molecule Interacting with CasL) are conserved multidomain enzymes essential for cytoskeletal reorganization in nerve development, endocytosis, and apoptosis. In these enzymes, a type-2 calponin homology (CH) domain always follows an N-terminal monooxygenase (MO) domain. Although the CH domain is required for MICAL-1 cellular localization and actin-associated function, its contribution to the modulation of MICAL activity towards actin remains unclear. Here, we present the structure of a fragment of MICAL-1 containing the MO and the CH domains-determined by X-ray crystallography and small angle scattering-as well as kinetics experiments designed to probe the contribution of the CH domain to the actin-modification activity. Our results suggest that the CH domain, which is loosely connected to the MO domain by a flexible linker and is far away from the catalytic site, couples F-actin to the enhancement of redox activity of MICALMO-CH by a cooperative mechanism involving a trans interaction between adjacently bound molecules. Binding cooperativity is also observed in other proteins regulating actin assembly/disassembly dynamics, such as ADF/Cofilins. Modulation of MICAL Monooxygenase Activity by its Calponin Homology Domain: Structural and Mechanistic Insights.,Alqassim SS, Urquiza M, Borgnia E, Nagib M, Amzel LM, Bianchet MA Sci Rep. 2016 Mar 3;6:22176. doi: 10.1038/srep22176. PMID:26935886[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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