Is peptide bond cis/trans isomerization a key stage in the chemo-mechanical cycle of motor proteins?
Motor proteins such as myosin and kinesin are responsible for actively directed movement in vivo. The physicochemical mechanism underlying their function is still obscure. A novel and unifying model concerning the motors driving mechanism is suggested here. This model resides within the framework of the well-studied "swinging lever-arm" hypothesis, stating that cis/trans peptide bond isomerization (CTI) is a key stage in the chemo-mechanical coupling within actomyosin--the complex of the motor (myosin) and its specific track (actin). CTI is suggested to propel myosin's lever-arm swing. The model addresses on the submolecular level a broad spectrum of actomyosin's functional characteristics, such as kinetics, energetics, force exertion, stepping, and directionality. The model may be tested first with relative ease in kinesin--a smaller motor that could be specifically modified with unnatural amino acids using bacterial expression. Suggested modifications may be used for labeling and functional decoupling.
Tchaicheeyan
Oren
O
Biomedical Engineering Department, Technion-Israel Institute of Technology, Haifa, 32000, Israel. toren@tx.technion.ac.il
D000205:Actomyosin / Q000737:chemistry / Q000502:physiology; D000255:Adenosine Triphosphate / Q000502:physiology; D000818:Animals; D001696:Biomechanical Phenomena; D004735:Energy Transfer; D007536:Isomerism; D016547:Kinesins / Q000737:chemistry / Q000502:physiology; D008954:Models, Biological; D020409:Molecular Motor Proteins / Q000737:chemistry* / Q000502:physiology; D009218:Myosins / Q000502:physiology; D019696:Peptidylprolyl Isomerase / Q000502:physiology; D011487:Protein Conformation; D011817:Rabbits; D013329:Structure-Activity Relationship; D019745:cis-trans-Isomerases / Q000502:physiology*
D020409:Molecular Motor Proteins; D000255:Adenosine Triphosphate; D000205:Actomyosin; D009218:Myosins; D016547:Kinesins; D019745:cis-trans-Isomerases; D019696:Peptidylprolyl Isomerase