Kinetic mechanism of human myosin IIIA

Andréa C. Dosé, Shobana Ananthanarayanan, Judy E. Moore, Beth Burnside, Christopher M. Yengo

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Myosin IIIA is specifically expressed in photoreceptors and cochlea and is important for the phototransduction and hearing processes. In addition, myosin IIIA contains a unique N-terminal kinase domain and C-terminal tail actin-binding motif. We examined the kinetic properties of baculovirus expressed human myosin IIIA containing the kinase, motor, and two IQ domains. The maximum actin-activated ATPase rate is relatively slow (kcat = 0.77 ± 0.08 s-1), and high actin concentrations are required to fully activate the ATPase rate (KATPase = 34 ± 11 μM). However, actin co-sedimentation assays suggest that myosin III has a relatively high steady-state affinity for actin in the presence of ATP (Kactin ∼ 7 μM). The rate of ATP binding to the motor domain is quite slow both in the presence and absence of actin (K1 k+2 = 0.020 and 0.001 μM-1·s-1, respectively). The rate of actin-activated phosphate release is more than 100-fold faster (85 s -1) than the kcat, whereas ADP release in the presence of actin follows a two-step mechanism (7.0 and 0.6 s-1). Thus, our data suggest a transition between two actomyosin-ADP states is the rate-limiting step in the actomyosin III ATPase cycle. Our data also suggest the myosin III motor spends a large fraction of its cycle in an actomyosin ADP state that has an intermediate affinity for actin (Kd ∼ 5 μM). The long lived actomyosin-ADP state may be important for the ability of myosin III to function as a cellular transporter and actin cross-linker in the actin bundles of sensory cells.

Original languageEnglish (US)
Pages (from-to)216-231
Number of pages16
JournalJournal of Biological Chemistry
Volume282
Issue number1
DOIs
StatePublished - Jan 5 2007

Fingerprint

Myosins
Actins
Kinetics
Myosin Type III
Actomyosin
Adenosine Diphosphate
Adenosine Triphosphatases
Phosphotransferases
Adenosine Triphosphate
Light Signal Transduction
Aptitude
Baculoviridae
Cochlea
Audition
Sedimentation
Hearing
Tail
Assays
Phosphates

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Dosé, A. C., Ananthanarayanan, S., Moore, J. E., Burnside, B., & Yengo, C. M. (2007). Kinetic mechanism of human myosin IIIA. Journal of Biological Chemistry, 282(1), 216-231. https://doi.org/10.1074/jbc.M605964200
Dosé, Andréa C. ; Ananthanarayanan, Shobana ; Moore, Judy E. ; Burnside, Beth ; Yengo, Christopher M. / Kinetic mechanism of human myosin IIIA. In: Journal of Biological Chemistry. 2007 ; Vol. 282, No. 1. pp. 216-231.
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Dosé, AC, Ananthanarayanan, S, Moore, JE, Burnside, B & Yengo, CM 2007, 'Kinetic mechanism of human myosin IIIA', Journal of Biological Chemistry, vol. 282, no. 1, pp. 216-231. https://doi.org/10.1074/jbc.M605964200

Kinetic mechanism of human myosin IIIA. / Dosé, Andréa C.; Ananthanarayanan, Shobana; Moore, Judy E.; Burnside, Beth; Yengo, Christopher M.

In: Journal of Biological Chemistry, Vol. 282, No. 1, 05.01.2007, p. 216-231.

Research output: Contribution to journalArticle

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Dosé AC, Ananthanarayanan S, Moore JE, Burnside B, Yengo CM. Kinetic mechanism of human myosin IIIA. Journal of Biological Chemistry. 2007 Jan 5;282(1):216-231. https://doi.org/10.1074/jbc.M605964200