Electron paramagnetic resonance and nanosecond fluorescence depolarization studies on creatine-phosphokinase interaction with myosin and its fragments

Muscle-specific creatine kinase gene polymorphism and VO2max in the HERITAGE Family Study

This study examined the association between a DNA polymorphism in the muscle-specific creatine kinase (CKMM) gene and VO2max in the sedentary state, as well as its response (deltaVO2max) to a standardized 20-wk endurance training program. The subjects were 160 biologically unrelated Caucasian parents (80 women, 80 men) and 80 biologically unrelated adult offspring of the HERITAGE Family Study. The CKMM polymorphism was detected by PCR and digestion with the NcoI restriction enzyme. VO2max was measured during maximal cycle ergometer tests. VO2max was 2119 +/- 45 mL x min(-1) (mean +/- SE) or 26 +/- 0.4 mL x kg(-1) x min(-1). Both sexes had a significant (P < 0.05) increase in the deltaVO2max (women = 283 +/- 20 mL x min[-1] and men = 363 +/- 25 mL x min[-1]). Allele and genotype frequencies were not significantly different (P > 0.05) between sexes. Age and sex adjusted VO2max was significantly (P = 0.007) associated with the CKMM genotype in the parents, whereas no association (P > 0.05) was observed in the offspring. DeltaVO2max values adjusted for age, sex, VO2max, and body mass were characterized by genotype differences in both parents (P = 0.0004) and offspring (P = 0.0025). A significantly (P < 0.05) lower deltaVO2max to endurance training was detected in both parents and offspring homozygotes for the rare allele. The genotype accounted for at least 9% of the variance in deltaVO2max. These results indicate that the NcoI polymorphism in the 3' untranslated region of the muscle-specific creatine kinase gene is associated with the deltaVO2max to endurance training.

An in vitro study of the interactions of skeletal muscle M-protein and creatine kinase with myosin and its subfragments

Two proteins reported to be located in the M-band of skeletal muscle are M-protein (Mr 160,000) and creatine kinase (Mr 83,000). We have isolated and purified these proteins from adult chicken pectoralis muscle, and have studied their in vitro interactions with myosin, heavy meromyosin, light meromyosin and subfragment-2 in order to obtain a fuller understanding of the role these proteins play in the M-band of skeletal muscle. Experiments using the techniques of analytical ultracentrifugation, affinity chromatography and electron microscopy were carried out near physiological pH and ionic strength, under which conditions the M-band proteins are known to be firmly bound to the myofibril in situ. The results of our studies indicate that such interactions are either weak or absent in vitro. Discrepancies between our results and those from several other studies are discussed. We conclude that additional components may be required in order to observe interactions in vitro which are similar to those present in the intact myofibril.

Novel staining pattern of skeletal muscle M-lines upon incubation with antibodies against MM-creatine kinase

Incubation of chicken skeletal muscle fibers with an excess of anti-M-creatine kinase (CK) immunoglobulin G and an excess of anti-M-CK Fab fragments leads to heavy decoration of the M-line (Wallimann, T., D.C. Turner, and H.M. Eppenberger, 1977, J. Cell Biol. 75:297-317) and to removal of the electron-dense M-line structure (Walliman, T., G. W. Pelloni, D.C. Turner, and H.M. Eppenberger, 1978, Proc. Natl. Acad. Sci. USA., 75:4296-4300), respectively. On the other hand, incubation with low concentrations of monovalent anti-M-CK Fab did not extract but rather decorated the M-line, giving rise to a distinct two-line staining pattern. A similar double-line staining pattern, although less pronounced, was also observed within the M-line of paraformaldehyde-prefixed myogenic cells, which after permeabilization were incubated with low concentrations of divalent anti-M-CK antibody. In both cases, the two decorated lines appearing in the middle of the A-band were spaced axially 42-44 nm apart and correspond most likely to the two M4 and M4' m-bridge rows described by Sjöström and Squire (1977, J. Mol. Biol., 109:49-68; 1977, J. Microscopy., 111:239-278). It is concluded that the muscle-specific form of creatine kinase, MM-CK, contributes mainly to the electron density of these M4 and M4' m-bridges within the M-line structure. This specific labeling pattern is a further demonstration that CK is an integral part of the M-line.

Ultrastructural localization of M-band proteins in chicken breast muscle as revealed by combined immunocytochemistry and ultramicrotomy

Cryo-ultramicrotomy and "conventional" plastic sectioning have been used in combination with extraction and immunolabeling techniques to determine the location of the two M-band proteins characterized to date, MM-creatine kinase (MM-CK: Mr, 80,000) and M-protein "myomesin" (Mr, 165,000) within the M-region of chicken pectoralis muscle. The following main results were obtained. (1) The M-band in chicken pectoralis muscle contains five major striations (M1, M4 and M4', M6 and M6' in the terminology of Sjöström & Squire, 1977a). (2) Extraction of the bulk of the electron-dense M-band with low ionic strength removes the M-striations M1, M4 and M4' while M6 and M6' are retained. Cross-sections through the M-region of such muscles lack primary M-bridges connecting the thick myosin filaments. (3) Labeling with antibodies against MM-CK enhances the M-striations M4 and M4'; sometimes the whole region between M4 and M4' is labeled. (4) Incubation with antibodies against myomesin results in the labeling of the whole M-band from M6 to M6'; no label is found in the rest of the bare zone outside M6 and M6'. (5) Incubation of low ionic strength extracted muscle fibers with antibodies against myomesin leads to an "incomplete" labeling of the M-band between M6 and M6'; lines M6 and M6' are sometimes seen to be enhanced presumably due to antibody labeling. From these results it is concluded that MM-CK is the major protein of the M4 and M4' (and possibly also of the M1) M-bridges. Myomesin is bound within the M-band along the thick filaments from M6 to M6'. Two hypothetical models for the possible location of myomesin are discussed. According to these models myomesin would either make up the M-filaments or be directly attached to and along the central bare zone of thick myosin filaments.

Postnatal development of the M-band in rat cardiac myofibrils

Cardiac muscle fibers in rats at 1 and 5 days after birth showed little evidence of M-bands. An ultrastructural analysis of myofibrils failed to demonstrate dense M-band material in longitudinal sections or M-bridges in transverse sections of sarcomeres. M-bands began to increase in number after 5 days of postnatal life and were present in 60% of all sarcomeres at 11 days of age. Polypeptides with molecular weights of 190,000 (Ma) and 175,000 (Mb) were obtained by polyacrylamide-sodium dodecyl sulfate (SDS) gel electrophoresis of myofibril preparations. These two proteins were found in both 1- and 11-day-old rats and were considered to be specific components of the M-band. The densitometric analysis demonstrated that Ma and mb polypeptides increased approximately 2-fold during the interval from 1 to 11 days after birth. These structural and biochemical changes of the M-band material in myocytes appear to be related to the maturation of contractile function in the young heart.

Transport of energy in muscle: the phosphorylcreatine shuttle

In order to explain the insulin-like effect of exercise, it was proposed in 1951 that contracting muscle fibers liberate creatine, which acts to produce an acceptor effect--later called respiratory control--on the muscle mitochondria. The development of this notion paralleled the controversy between biochemists and physiologists over the delivery of energy for muscle contraction. With the demonstration of functional compartmentation of creatine kinase on the mitochondrion, it became clear that the actual form of energy transport in the muscle fiber is phosphorylcreatine. The finding of an isoenzyme of creatine phosphokinase attached to the M-line region of the myofibril revealed the peripheral receptor for the mitochondrially generated phosphorylcreatine. This established a molecular basis for a phosphorylcreatine-creatine shuttle for energy transport in heart and skeletal muscle and provided an explanation for the inability to demonstrate experimentally a direct relation between muscle activity and the concentrations of adenosine triphosphate and adenosine diphosphate.

Biochemical and ultrastructural aspects of Mr 165,000 M-protein in cross-striated chicken muscle

To better understand the relationship between the Mr 165,000 M-line protein (M-protein) and H-zone structure in skeletal and in cardiac muscle, as well as the possible interaction of M-protein with another skeletal muscle M-line component, the homodimeric creatine kinase isoenzyme composed of two M subunits (MM-CK), we performed biochemical, immunological, and ultrastructural studies on myofibrils extracted by different procedures. In contrast to MM-CK, M-protein could not be completely removed from myofibrils by low ionic strength extraction. Fab-fragments of antibodies against M-protein could not release M-protein quantitatively from either breast or heart myofibrils but remained bound to the myofibrillar structure, whereas monovalent antibodies against MM-CK cause the specific release of MM-CK and the concomitant disappearance of the M-line from chicken skeletal muscle myofibrils. When MM-CK was removed from skeletal myofibrils by low ionic strength extraction or, more specifically, by incubation with anti-MM-CK Fab, M-protein was still not released quantitatively upon treatment with anti-M-protein Fab as judged from immunofluorescence data. In the ultrastructural investigation of low ionic strength extracted muscle fibers, M protein could be localized in two stripes on both sides of the former M-line, suggesting a reduced attachment to the residual H-zone structure, whereas the specific removal of MM-CK resulted in the same dense staining pattern for M-protein within the M-line as observed in untreated fibers. However, the binding of M-protein to the residual M-line structure seemed to be reduced, as a considerable amount of this protein could be identified in the supernate of sequentially incubated myofibrils. The results indicate a strong binding of M-protein within the H-zone structure of skeletal as well as heart myofibrils.

Physicochemical studies on the creatine kinase M-line protein and its interaction with myosin and myosin fragments

The M-line protein which is identical to the muscle form of creatine kinase was purified from rabbit skeletal muscle using ion exchange chromatography. Gel electrophoresis in the presence and absence of sodium dodecyl sulfate revealed the protein to be homogeneous. Sodium dodecyl sulfate gel electrophoresis gave 44 000 +/- 2000 as the minimum molecular weight while low speed sedimentation equilibrium experiments yielded a molecular weight of 84 000 +/- 4000, suggesting that the parent molecule is a dimer. Circular dichroism spectra revealed the presence of two negative dichroic bands located at 218 and 208 nm suggesting the presence of some beta-structure. Ellipticity values at these two wavelengths were -8000 +/- 400 and -9000 +/- 400 deg-cm2-dmol-1. Circular dichroism measurements indicated the protein to interact with myosin, heavy meromyosin and heavy meromyosin subfragment 1 (S1). The Ca2+-activated ATPase activities of myosin, heavy meromyosin and subfragment 1 were inhibited by the addition of M-line protein. When the protein was mixed with subfragment 1 in a 1:1 mole ratio in 0.15 M KC1, 50 mM Tris pH 8, low speed sedimentation equilibrium studies gave a molecular weight of 205 000 +/- 10 000 for the complex, indicative of an interaction of the two components. Both circular dichroism and sedimentation equilibrium studies indicated no interaction of M-line protein with light meromyosin.