Regulation of Drosophila myosin ATPase activity by phosphorylation of myosin light chains--II. Flightless mfd- fly
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S Takahashi1, H Takano-Ohmuro, K Maruyama
1Department of Biology, Faculty of Science, Chiba University, Japan.
Abstract:
1. The Ca2(+)-activated and Mg2+ actin-activated myosin ATPase activities of flightless mfd- mutant Drosophila flight muscle myosin were one-half and one-third of those of the wild-type fly muscle myosin, respectively. 2. In the two-dimensional gel electrophoresis, the spots corresponding to phosphorylated myosin light chains, Lfl and Ltl, were hardly detected in mfd- mutant myosin. 3. These results support not only the conclusion that phosphorylation of myosin light chains regulates Drosophila myosin ATPase activity but also the assumption that the phosphorylation of myosin light chains is directly involved in flight function of the Drosophila fly.
Insights
Phosphorylation of myosin light chains is crucial for Drosophila flight muscle function. Reduced phosphorylation in flightless mutants significantly impairs myosin ATPase activity, highlighting its role in flight.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Myosin ATPase activity is essential for muscle contraction.
- Myosin light chains (MLCs) are regulatory subunits of myosin.
- Phosphorylation of MLCs is implicated in regulating myosin function.
Purpose of the Study:
- To investigate the role of myosin light chain phosphorylation in Drosophila flight muscle.
- To determine the impact of impaired flight function on myosin ATPase activity and phosphorylation status.
Main Methods:
- Biochemical assays to measure Ca2+-activated and Mg2+-actin-activated myosin ATPase activities.
- Two-dimensional gel electrophoresis to analyze myosin light chain phosphorylation patterns.
Main Results:
- Flightless mfd- mutant Drosophila flight muscle myosin exhibited significantly reduced Ca2+-activated (50%) and Mg2+-actin-activated (33%) ATPase activities compared to wild-type.
- Two-dimensional gel electrophoresis revealed a near absence of phosphorylated myosin light chains (Lfl and Ltl) in the mfd- mutant myosin.
Conclusions:
- Myosin light chain phosphorylation directly regulates Drosophila myosin ATPase activity.
- The phosphorylation of myosin light chains is essential for proper flight function in Drosophila.