Muscle-type Creatine Kinase Interacts with Central Domains of the M-band Proteins Myomesin and M-protein

• Published in: Journal of molecular biology 2003-09, Vol.332 (4), p.877-887
• Main Authors: Hornemann, Thorsten, Kempa, Stefan, Himmel, Mirko, Hayeß, Katrin, Fürst, Dieter O., Wallimann, Theo
• Format: Article
• Language: English
• Subjects: Animals; Chickens; Connectin; creatine kinase; Creatine Kinase - genetics; Creatine Kinase - metabolism; Creatine Kinase, MM Form; Humans; Hydrogen-Ion Concentration; Isoenzymes - genetics; Isoenzymes - metabolism; Lysine - metabolism; M-protein; Muscle Proteins - genetics; Muscle Proteins - metabolism; myomesin; Point Mutation; Protein Binding; Protein Structure, Tertiary; sarcomeric M-band; titin; Two-Hybrid System Techniques
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1016/S0022-2836(03)00921-5

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 μM, 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.