title: Muscle-type creatine kinase interacts with central domains of the M-band proteins myomesin and M-protein.
abstract: Muscle-type creatine kinase (MM-CK) is a member of the CK isoenzyme family with key functions in cellular energetics. MM-CK interacts in an isoform-specific manner with the M-band of sarcomeric muscle, where it serves as an efficient intramyofibrillar ATP-regenerating system for the actin-activated myosin ATPase located nearby on both sides of the M-band. Four MM-CK-specific and highly conserved lysine residues are thought to be responsible for the interaction of MM-CK with the M-band. A yeast two-hybrid screen led to the identification of MM-CK as a binding partner of a central portion of myomesin (My7-8). An interaction was observed with domains six to eight of the closely related M-protein but not with several other Ig-like domains, including an M-band domain, of titin. The observed interactions were corroborated and characterised in detail by surface plasmon resonance spectroscopy (BiaCore). In both cases, they were CK isoform-specific and the MM-CK-specific lysine residues (K8. K24, K104 and K115) are involved in this interaction. At pH 6.8, the dissociation constants for the myomesin/MM-CK and the M-protein/MM-CK binding were in the range of 50-100 nM and around 1 microM, respectively. The binding showed pronounced pH-dependence and indicates a dynamic association/dissociation behaviour, which most likely depends on the energy state of the muscle. Our data propose a simple model for the regulation of this dynamic interaction.
authors.affiliation: Institute of Cell Biology, Swiss Federal Institute of Technology, CH-8093 Zürich, Switzerland.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Hornemann
authors.forename: Stefan
authors.initials: S
authors.lastname: Kempa
authors.forename: Mirko
authors.initials: M
authors.lastname: Himmel
authors.forename: Katrin
authors.initials: K
authors.lastname: Hayess
authors.forename: Dieter O
authors.initials: DO
authors.lastname: Fürst
authors.forename: Theo
authors.initials: T
authors.lastname: Wallimann
mesh_terms: D000818:Animals; D002645:Chickens; D064211:Connectin; D003402:Creatine Kinase / Q000235:genetics / Q000378:metabolism*; D052283:Creatine Kinase, MM Form; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D020798:Two-Hybrid System Techniques
chemical_list: D064211:Connectin; D007527:Isoenzymes; D009124:Muscle Proteins; D003402:Creatine Kinase; D052283:Creatine Kinase, MM Form; D008239:Lysine