Dimerisation of myomesin: implications for the structure of the sarcomeric M-band.
The sarcomeric M-band is thought to provide a link between the thick and the elastic filament systems. So far, relatively little is known about its structural components and their three-dimensional organisation. Myomesin seems to be an essential component of the M-band, since it is expressed in all types of vertebrate striated muscle fibres investigated and can be found in its mature localisation pattern as soon as the first myofibrils are assembled. Previous work has shown that the N-terminal and central part of myomesin harbour binding sites for myosin, titin and muscle creatine kinase. Intrigued by the highly conserved domain layout of the C-terminal half, we screened for new interaction partners by yeast two-hybrid analysis. This revealed a strong interaction of myomesin with itself. This finding was confirmed by several biochemical assays. Our data suggest that myomesin can form antiparallel dimers via a binding site residing in its C-terminal domain 13. We suggest that, similar to alpha-actinin in the Z-disc, the myomesin dimers cross-link the contractile filaments in the M-band. The new and the already previously identified myomesin interaction sites are integrated into the first three-dimensional model of the sarcomeric M-band on a molecular basis.
Lange
Stephan
S
Institute of Cell Biology, ETH Zurich-Honggerberg, CH-8093 Zurich, Switzerland.
Himmel
Mirko
M
Auerbach
Daniel
D
Agarkova
Irina
I
Hayess
Katrin
K
Fürst
Dieter O
DO
Perriard
Jean-Claude
JC
Ehler
Elisabeth
E
D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry; D001665:Binding Sites; D015153:Blotting, Western; D019556:COS Cells; D064211:Connectin; D003402:Creatine Kinase / Q000378:metabolism; D052283:Creatine Kinase, MM Form; D003432:Cross-Linking Reagents / Q000494:pharmacology; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer; D005982:Glutathione Transferase / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D015151:Immunoblotting; D047468:Immunoprecipitation; D007527:Isoenzymes / Q000378:metabolism; D008958:Models, Molecular; D009124:Muscle Proteins / Q000737:chemistry*; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011494:Protein Kinases / Q000737:chemistry; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D012518:Sarcomeres / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D000911:Antibodies, Monoclonal; D064211:Connectin; D003432:Cross-Linking Reagents; C485182:Cyan Fluorescent Protein; D000939:Epitopes; D007527:Isoenzymes; D009124:Muscle Proteins; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; D005982:Glutathione Transferase; D011494:Protein Kinases; D003402:Creatine Kinase; D052283:Creatine Kinase, MM Form