Myosin-1a Is Critical for Normal Brush Border Structure and Composition

Tyska, Matthew J.; Mackey, Andrew T.; Huang, Jian; Copeland, Neal G.; Jenkins, Nancy A.; Mooseker, Mark S.

doi:10.1091/mbc.e04-12-1116

Cited by 173 publications

(253 citation statements)

References 49 publications

Supporting

Mentioning

236

Contrasting

Order By: Relevance

“…If we assume a rigid myo1b lever arm, and we assume that the powerstroke must be completed before ADP is released, we estimate the effect of force on the duty ratio of myo1b (36)(37)(38), (6) where k +5,force ′ is the rate of ADP release in the presence of external force, F is the external force, d is the distance the end of the lever arm travels upon release of ADP, and k b T is thermal energy (4.3 pN·nm at 37 °C). Assuming d = 5.5 nm (35), a plot of the duty ratio as a function of force shows that the duty ratio of myo1b is greater than 0.5 at resisting forces as low as 2 pN.…”

Section: Duty Ratiomentioning

confidence: 99%

Temperature Dependence of Nucleotide Association and Kinetic Characterization of Myo1b

et al. 2006

View full text Add to dashboard Cite

Myo1b is a widely expressed myosin-I isoform that concentrates on endosomal and ruffling membranes and is thought to play roles in membrane trafficking and dynamics. It is one of the best characterized myosin-I isoforms and appears to have unique biochemical properties tuned for tension sensing or tension maintenance. We determined the key biochemical rate constants that define the actomyo1b ATPase cycle at 37 °C and measured the temperature dependence of ATP binding, ADP release, and the transition from a nucleotide inaccessible state to a nucleotide accessible state (kalpha). The rate of ATP binding is highly temperature sensitive, with an Arrhenius activation energy 2-3 fold greater than other characterized myosins (e.g, myosin-II and myosin-V). ATP hydrolysis is fast, and phosphate release is slow and rate limiting with an actin dependence that is nearly identical to the steady-state ATPase parameters (V max and K ATPase ). ADP release is not as temperature dependent as ATP binding. The rates and temperature dependence of ADP release are similar to kalpha suggesting a similar structural change is responsible for both transitions. We calculate a duty ratio of 0.08 based on the biochemical kinetics. However, this duty ratio is likely to be highly sensitive to strain.Myosin-Is are the single-headed, low-molecular-weight members of the myosin superfamily that are proposed to link cellular membranes with the actin cytoskeleton. Myosin-I isoforms bind phosphoinositides directly (1) and function in several important cellular processes, including membrane retraction, macropinocytosis, phagocytosis, membrane trafficking, cellcell adhesion, and mechanical signal transduction (2-8).The biochemical mechanisms of long-tail and short-tail myosin-I isoforms have been studied (9-12), with myo1b being the best characterized short-tail isoform (13)(14)(15). The myo1b ATPase mechanism (Scheme 1) is notable in that (a) the maximum rate of ATP binding and population of the myo1b IQ weakly-bound states is > 30-fold slower than myosin-II, (b) nucleotide-free myo1b is in equilibrium between a state that binds nucleotide (AM′) and a state that does not bind nucleotide (AM), (c) the rate of transition between AM and AM′ (k +α ) states is similar to the rate of ADP release (k +5 ′), and (d) ADP release is slow and is accompanied by a rotation of the lever arm.We proposed that the strikingly slow actomyo1b ATPase rate constants are a property of all short-tail myosin-I isoforms (11,16). However, it has been shown recently that short-tailed Dictyostelium myosin-IE (not to be confused with vertebrate long-tail myo1e (11)) has kinetic rate constants that are substantially faster than vertebrate short-tail isoforms (12). Because of † EMO was supported by grants from the National Institutes of Health (GM57247 and AR051174). JHL was supported by a training grant from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (AR053461). *Corresponding author: E. Michael Ostap, Department of Physiology, University of Pe...

show abstract

Section: Duty Ratiomentioning

confidence: 99%

Temperature Dependence of Nucleotide Association and Kinetic Characterization of Myo1b

et al. 2006

View full text Add to dashboard Cite

show abstract

“…One candidate molecule for carrying out this task is myosin-1a (Myo1a), a monomeric actin-based motor protein that is present at high levels in the microvillus and is known to bind directly to phospholipids by virtue of its basic C-terminal tail homology 1 (TH1) domain (9,10). Myo1a KO mice exhibit large apical membrane herniations that are morphologically similar to ''blebs'' (11,12). Because blebs represent complete delamination of membrane from the actin cytoskeleton, these results suggest that Myo1a makes a major contribution to membrane-cytoskeleton adhesion in the brush border.…”

mentioning

confidence: 99%

Control of cell membrane tension by myosin-I

Nambiar

McConnell²,

Tyska³

2009

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

166

137

View full text Add to dashboard Cite

All cell functions that involve membrane deformation or a change in cell shape (e.g., endocytosis, exocytosis, cell motility, and cytokinesis) are regulated by membrane tension. While molecular contacts between the plasma membrane and the underlying actin cytoskeleton are known to make significant contributions to membrane tension, little is known about the molecules that mediate these interactions. We used an optical trap to directly probe the molecular determinants of membrane tension in isolated organelles and in living cells. Here, we show that class I myosins, a family of membrane-binding, actin-based motor proteins, mediate membrane/cytoskeleton adhesion and thus, make major contributions to membrane tension. These studies show that class I myosins directly control the mechanical properties of the cell membrane; they also position these motor proteins as master regulators of cellular events involving membrane deformation.actin ͉ brush border ͉ cytoskeleton ͉ microvilli ͉ optical trap

show abstract

“…30,31 A long BB with high expression of membranous transporters and enzymes is a hallmark of fully differentiated epithelial cells. As a prominent site for digestive and absorptive functions, the length of the BB on epithelial cells of the small intestine is longer than that of the large intestine.…”

Section: Brush Bordersmentioning

confidence: 99%

Commensal bacterial internalization by epithelial cells: An alternative portal for gut leakiness

2015

Tissue Barriers

View full text Add to dashboard Cite

Myosin-1a Is Critical for Normal Brush Border Structure and Composition

Cited by 173 publications

References 49 publications

Temperature Dependence of Nucleotide Association and Kinetic Characterization of Myo1b

Temperature Dependence of Nucleotide Association and Kinetic Characterization of Myo1b

Control of cell membrane tension by myosin-I

Commensal bacterial internalization by epithelial cells: An alternative portal for gut leakiness

Contact Info

Product

Resources

About