title: Distinct interactions between actin and essential myosin light chain isoforms.
abstract: Binding of the utmost N-terminus of essential myosin light chains (ELC) to actin slows down myosin motor function. In this study, we investigated the binding constants of two different human cardiac ELC isoforms with actin. We employed circular dichroism (CD) and surface plasmon resonance (SPR) spectroscopy to determine structural properties and protein-protein interaction of recombinant human atrial and ventricular ELC (hALC-1 and hVLC-1, respectively) with α-actin as well as α-actin with alanin-mutated ELC binding site (α-actin(ala3)) as control. CD spectroscopy showed similar secondary structure of both hALC-1 and hVLC-1 with high degree of α-helicity. SPR spectroscopy revealed that the affinity of hALC-1 to α-actin (KD=575 nM) was significantly (p<0.01) lower compared with the affinity of hVLC-1 to α-actin (KD=186 nM). The reduced affinity of hALC-1 to α-actin was mainly due to a significantly (p<0.01) lower association rate (kon: 1,018 M(-1)s(-1)) compared with kon of the hVLC-1/α-actin complex interaction (2,908 M(-1)s(-1)). Hence, differential expression of ELC isoforms could modulate muscle contractile activity via distinct α-actin interactions.
authors.affiliation: Max-Delbrück-Center for Molecular Medicine, Dept. of Molecular Muscle Physiology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany.
authors.forename: Daria
authors.initials: D
authors.lastname: Petzhold
authors.affiliation: Max-Delbrück-Center for Molecular Medicine, Dept. of Molecular Muscle Physiology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany.
authors.forename: Burcu
authors.initials: B
authors.lastname: Simsek
authors.affiliation: Max-Delbrück-Center for Molecular Medicine, Dept. of Molecular Muscle Physiology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Meißner
authors.affiliation: Max-Delbrück-Center for Molecular Medicine, Dept. of Molecular Muscle Physiology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany.
authors.forename: Shokoufeh
authors.initials: S
authors.lastname: Mahmoodzadeh
authors.affiliation: Max-Delbrück-Center for Molecular Medicine, Dept. of Molecular Muscle Physiology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany; University Medicine Charité Berlin, Charitéplatz 1, 10117 Berlin, Germany. Electronic address: imorano@mdc-berlin.de.
authors.forename: Ingo
authors.initials: I
authors.lastname: Morano
mesh_terms: D000199:Actins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D024743:Atrial Myosins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002942:Circular Dichroism; D006801:Humans; D009200:Myocardial Contraction; D018994:Myosin Light Chains / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020349:Surface Plasmon Resonance; D024723:Ventricular Myosins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D018994:Myosin Light Chains; D020033:Protein Isoforms; D011994:Recombinant Proteins; D024743:Atrial Myosins; D024723:Ventricular Myosins
keywords: Actin interaction; Essential myosin light chains; Surface plasmon resonance