title: N-lobe dynamics of myosin light chain dictates its mode of interaction with myosin V IQ1.
abstract: Myosin V motors regulate secretion and cell division in eukaryotes. How MyoV activity is differentially regulated by essential and calmodulin light chain binding remains unclear. We have used NMR spectroscopy to compare the dynamic behavior of Mlc1p, a budding yeast essential light chain, with that of the Xenopus laevis calmodulin. Both proteins have a similar structure and bind similar target proteins but differ in the mechanism by which they interact with the myosin V IQ1. This interaction is essential for MyoV activity. Here, we show that the rigid conformation of the loop connecting the two EF-hand motifs of the Mlc1p N-lobe explains its differential ability to interact with myosin V IQ1. Moreover, we show that the maintenance of the N-lobe structure is required for the essential function of Mlc1p in vivo. These data show that the core characteristics of myosin light chain N-lobes differentiate Mlc1p and calmodulin binding capability.
authors.affiliation: Department of Chemical Science and Technology, University of Rome Tor Vergata, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Amata
authors.forename: Mariana
authors.initials: M
authors.lastname: Gallo
authors.forename: Matteo
authors.initials: M
authors.lastname: Pennestri
authors.forename: Maurizio
authors.initials: M
authors.lastname: Paci
authors.forename: Antonella
authors.initials: A
authors.lastname: Ragnini-Wilson
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Cicero
mesh_terms: D000483:Alleles; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002147:Calmodulin / Q000737:chemistry / Q000378:metabolism; D002470:Cell Survival; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D009068:Movement; D018994:Myosin Light Chains / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D024701:Myosin Type V / Q000737:chemistry* / Q000378:metabolism*; D010641:Phenotype; D017354:Point Mutation; D011485:Protein Binding; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013696:Temperature; D029867:Xenopus Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D002147:Calmodulin; C113979:MLC1 protein, S cerevisiae; D018994:Myosin Light Chains; D029701:Saccharomyces cerevisiae Proteins; D029867:Xenopus Proteins; D024701:Myosin Type V