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Solution structure of C-lobe Myosin Light Chain from Saccharomices cerevisiae
Structural highlights
FunctionMLC1_YEAST Essential light chain for the class II conventional myosin MYO1. Acts also as light chain for the class V unconventional myosin MYO2 and for IQG1. Involved in the assembly of the contractile actomyosin ring at the bud neck during cytokinesis by recruiting IQG1 to the bud neck. Also required for chitin and MYO2-dependent secretory vesicle deposition to the center of the bud neck for septum formation. May stabilize MYO2 by binding to its IQ domains. Its major function is probably not to regulate MYO1 activity, but rather to coordinate actin ring formation and targeted membrane deposition during cytokinesis via its interactions with MYO1, IQG1 and MYO2.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedCalmodulin, regulatory, and essential myosin light chain are evolutionary conserved proteins that, by binding to IQ motifs of target proteins, regulate essential intracellular processes among which are efficiency of secretory vesicles release at synapsis, intracellular signaling, and regulation of cell division. The yeast Saccharomyces cerevisiae calmodulin Cmd1 and the essential myosin light chain Mlc1p share the ability to interact with the class V myosin Myo2p and Myo4 and the class II myosin Myo1p. These myosins are required for vesicle, organelle, and mRNA transport, spindle orientation, and cytokinesis. We have used the budding yeast model system to study how calmodulin and essential myosin light chain selectively regulate class V myosin function. NMR structural analysis of uncomplexed Mlc1p and interaction studies with the first three IQ motifs of Myo2p show that the structural similarities between Mlc1p and the other members of the EF-hand superfamily of calmodulin-like proteins are mainly restricted to the C-lobe of these proteins. The N-lobe of Mlc1p presents a significantly compact and stable structure that is maintained both in the free and complexed states. The Mlc1p N-lobe interacts with the IQ motif in a manner that is regulated both by the IQ motifs sequence as well as by light chain structural features. These characteristic allows a distinctive interaction of Mlc1p with the first IQ motif of Myo2p when compared with calmodulin. This finding gives us a novel view of how calmodulin and essential light chain, through a differential binding to IQ1 of class V myosin motor, regulate this activity during vegetative growth and cytokinesis. Structural basis for the interaction of the myosin light chain Mlc1p with the myosin V Myo2p IQ motifs.,Pennestri M, Melino S, Contessa GM, Casavola EC, Paci M, Ragnini-Wilson A, Cicero DO J Biol Chem. 2007 Jan 5;282(1):667-79. Epub 2006 Oct 29. PMID:17074768[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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