title: Structure of the Single-lobe Myosin Light Chain C in Complex with the Light Chain-binding Domains of Myosin-1C Provides Insights into Divergent IQ Motif Recognition.
abstract: Myosin light chains are key regulators of class 1 myosins and typically comprise two domains, with calmodulin being the archetypal example. They bind IQ motifs within the myosin neck region and amplify conformational changes in the motor domain. A single lobe light chain, myosin light chain C (MlcC), was recently identified and shown to specifically bind to two sequentially divergent IQ motifs of the Dictyostelium myosin-1C. To provide a molecular basis of this interaction, the structures of apo-MlcC and a 2:1 MlcC·myosin-1C neck complex were determined. The two non-functional EF-hand motifs of MlcC pack together to form a globular four-helix bundle that opens up to expose a central hydrophobic groove, which interacts with the N-terminal portion of the divergent IQ1 and IQ2 motifs. The N- and C-terminal regions of MlcC make critical contacts that contribute to its specific interactions with the myosin-1C divergent IQ motifs, which are contacts that deviate from the traditional mode of calmodulin-IQ recognition.
authors.affiliation: From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: David N
authors.initials: DN
authors.lastname: Langelaan
authors.affiliation: From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Janine
authors.initials: J
authors.lastname: Liburd
authors.affiliation: From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Yidai
authors.initials: Y
authors.lastname: Yang
authors.affiliation: From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Emily
authors.initials: E
authors.lastname: Miller
authors.affiliation: From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Seth
authors.initials: S
authors.lastname: Chitayat
authors.affiliation: From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Scott W
authors.initials: SW
authors.lastname: Crawley
authors.affiliation: From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada coteg@queensu.ca.
authors.forename: Graham P
authors.initials: GP
authors.lastname: Côté
authors.affiliation: From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada steven.smith@queensu.ca.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Smith
mesh_terms: D020816:Amino Acid Motifs; D004023:Dictyostelium / Q000201:enzymology* / Q000235:genetics; D018994:Myosin Light Chains / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000072417:Protein Domains; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D018994:Myosin Light Chains; D015800:Protozoan Proteins
keywords: EF-hand; IQ motif; light chain; myosin; nuclear magnetic resonance (NMR); protein motif; protein structure; protein-protein interaction; structural biology; x-ray crystallography