TY - JOUR
T1 - A Restrictive Cardiomyopathy Mutation in an Invariant Proline at the Myosin Head/Rod Junction Enhances Head Flexibility and Function, Yielding Muscle Defects in Drosophila
AU - Achal, Madhulika
AU - Trujillo, Adriana S.
AU - Melkani, Girish C.
AU - Farman, Gerrie P.
AU - Ocorr, Karen
AU - Viswanathan, Meera C.
AU - Kaushik, Gaurav
AU - Newhard, Christopher S.
AU - Glasheen, Bernadette M.
AU - Melkani, Anju
AU - Suggs, Jennifer A.
AU - Moore, Jeffrey R.
AU - Swank, Douglas M.
AU - Bodmer, Rolf
AU - Cammarato, Anthony
AU - Bernstein, Sanford I.
N1 - Funding Information:
We sincerely appreciate the molecular biology advice provided by William A. Kronert (SDSU) and the production of some of the myosin preparations by Floyd Sarsoza (SDSU). We thank Adam Engler (UCSD) for providing suggestions regarding the analysis of myosin head orientations and Tom Huxford (SDSU) for insights on myosin structure. This research was supported by NIH grants R01GM32443 to S.I.B. and R56HL124091 to A.C., as well as AHA grant 10SDG4180089 to A.C. A.S.T. is a fellow of the Rees-Stealy Research Foundation and the San Diego State University Heart Institute. G.K. was supported by a predoctoral fellowship from the American Heart Association ( 13PRE14410037 ). The content is solely the responsibility of the authors and does not necessarily represent the official views of the sponsoring organizations.
Funding Information:
This research was supported by NIH grants R01GM32443 to S.I.B. and R56HL124091 to A.C., as well as AHA grant 10SDG4180089 to A.C. A.S.T. is a fellow of the Rees-Stealy Research Foundation and the San Diego State University Heart Institute. G.K. was supported by a predoctoral fellowship from the American Heart Association (13PRE14410037).
Publisher Copyright:
© 2016 Elsevier Ltd. All rights reserved.
PY - 2016/6/5
Y1 - 2016/6/5
N2 - An "invariant proline" separates the myosin S1 head from its S2 tail and is proposed to be critical for orienting S1 during its interaction with actin, a process that leads to muscle contraction. Mutation of the invariant proline to leucine (P838L) caused dominant restrictive cardiomyopathy in a pediatric patient (Karam et al., Congenit. Heart Dis. 3:138-43, 2008). Here, we use Drosophila melanogaster to model this mutation and dissect its effects on the biochemical and biophysical properties of myosin, as well as on the structure and physiology of skeletal and cardiac muscles. P838L mutant myosin isolated from indirect flight muscles of transgenic Drosophila showed elevated ATPase and actin sliding velocity in vitro. Furthermore, the mutant heads exhibited increased rotational flexibility, and there was an increase in the average angle between the two heads. Indirect flight muscle myofibril assembly was minimally affected in mutant homozygotes, and isolated fibers displayed normal mechanical properties. However, myofibrils degraded during aging, correlating with reduced flight abilities. In contrast, hearts from homozygotes and heterozygotes showed normal morphology, myofibrillar arrays, and contractile parameters. When P838L was placed in trans to MHC5, an allele known to cause cardiac restriction in flies, it did not yield the constricted phenotype. Overall, our studies suggest that increased rotational flexibility of myosin S1 enhances myosin ATPase and actin sliding. Moreover, instability of P838L myofibrils leads to decreased function during aging of Drosophila skeletal muscle, but not cardiac muscle, despite the strong evolutionary conservation of the P838 residue.
AB - An "invariant proline" separates the myosin S1 head from its S2 tail and is proposed to be critical for orienting S1 during its interaction with actin, a process that leads to muscle contraction. Mutation of the invariant proline to leucine (P838L) caused dominant restrictive cardiomyopathy in a pediatric patient (Karam et al., Congenit. Heart Dis. 3:138-43, 2008). Here, we use Drosophila melanogaster to model this mutation and dissect its effects on the biochemical and biophysical properties of myosin, as well as on the structure and physiology of skeletal and cardiac muscles. P838L mutant myosin isolated from indirect flight muscles of transgenic Drosophila showed elevated ATPase and actin sliding velocity in vitro. Furthermore, the mutant heads exhibited increased rotational flexibility, and there was an increase in the average angle between the two heads. Indirect flight muscle myofibril assembly was minimally affected in mutant homozygotes, and isolated fibers displayed normal mechanical properties. However, myofibrils degraded during aging, correlating with reduced flight abilities. In contrast, hearts from homozygotes and heterozygotes showed normal morphology, myofibrillar arrays, and contractile parameters. When P838L was placed in trans to MHC5, an allele known to cause cardiac restriction in flies, it did not yield the constricted phenotype. Overall, our studies suggest that increased rotational flexibility of myosin S1 enhances myosin ATPase and actin sliding. Moreover, instability of P838L myofibrils leads to decreased function during aging of Drosophila skeletal muscle, but not cardiac muscle, despite the strong evolutionary conservation of the P838 residue.
KW - Drosophila melanogaster
KW - contraction
KW - electron microscopy
KW - motility
KW - myofibril
UR - http://www.scopus.com/inward/record.url?scp=84965042589&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84965042589&partnerID=8YFLogxK
U2 - 10.1016/j.jmb.2016.04.021
DO - 10.1016/j.jmb.2016.04.021
M3 - Article
C2 - 27107639
AN - SCOPUS:84965042589
SN - 0022-2836
VL - 428
SP - 2446
EP - 2461
JO - Journal of molecular biology
JF - Journal of molecular biology
IS - 11
ER -