Interaction of elongation factor 1α from <i>Zea mays</i> (ZmEF‐1α) with F‐actin and interplay with the maize actin severing protein, ZmADF3

Gungabissoon, Ravine A.; Khan, Safina; Hussey, Patrick J.; Maciver, Sutherland K.

doi:10.1002/cm.1024

Cited by 28 publications

(14 citation statements)

References 43 publications

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“…Gelsolin-severed short actin filaments (up to 1:50 molar ratios of gelsolin and actin) were efficiently bundled by UNC-87 (our unpublished data), suggesting that the inhibitory effect of UNC-60B is not simply due to shortening of the filaments. This antagonistic effect contrasts the previously reported synergistic effects on actin bundling between ADF/cofilin and ␣-actinin (Maciver et al, 1991a) or elongation factor 1␣ (Gungabissoon et al, 2001). …”

Section: Unc-87contrasting

confidence: 98%

UNC-87, a calponin-related protein in C. elegans, antagonizes ADF/cofilin-mediated actin filament dynamics

Yamashiro

Gimona²,

Ono

2007

Journal of Cell Science

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Stabilization of actin filaments is critical for supporting actomyosin-based contractility and for maintaining stable cellular structures. Tropomyosin is a well-characterized ubiquitous actin stabilizer that inhibits ADF/cofilindependent actin depolymerization. Here, we show that UNC-87, a calponin-related Caenorhabditis elegans protein with seven calponin-like repeats, competes with ADF/cofilin for binding to actin filaments and inhibits ADF/cofilin-dependent filament severing and depolymerization in vitro. Mutations in the unc-87 gene suppress the disorganized actin phenotype in an ADF/cofilin mutant in the C. elegans body wall muscle, supporting their antagonistic roles in regulating actin stability in vivo. UNC-87 and tropomyosin exhibit synergistic effects in stabilizing actin filaments against ADF/cofilin, and direct comparison reveals that UNC-87 effectively stabilizes actin filaments at much lower concentrations than tropomyosin. However, the in vivo functions of UNC-87 and tropomyosin appear different, suggesting their distinct roles in the regulation of actomyosin assembly and cellular contractility. Our results demonstrate that actin binding via calponin-like repeats competes with ADF/cofilin-driven cytoskeletal turnover, and is critical for providing the spatiotemporal regulation of actin filament stability.

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Section: Unc-87contrasting

confidence: 98%

UNC-87, a calponin-related protein in C. elegans, antagonizes ADF/cofilin-mediated actin filament dynamics

Yamashiro

Gimona²,

Ono

2007

Journal of Cell Science

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“…The regulation of fimbrin binding activity to F-actin is still unclear, but its activity is [Ca 21 ] insensitive (Kovar et al, 2000). Elongation factor-1a is a dual-function protein with aminoacyl tRNA binding as well as actin-binding and -bundling activities (Gungabissoon et al, 2001). In this study, we demonstrated that pH and [Ca 21 ] can simultaneously regulate the F-actin binding of LlLIM1.…”

mentioning

confidence: 76%

An Actin-Binding Protein, LlLIM1, Mediates Calcium and Hydrogen Regulation of Actin Dynamics in Pollen Tubes

2008

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Actin microfilaments are crucial for polar cell tip growth, and their configurations and dynamics are regulated by the actions of various actin-binding proteins (ABPs). We explored the function of a lily (Lilium longiflorum) pollen-enriched LIM domain-containing protein, LlLIM1, in regulating the actin dynamics in elongating pollen tube. Cytological and biochemical assays verified LlLIM1 functioning as an ABP, promoting filamentous actin (F-actin) bundle assembly and protecting F-actin against latrunculin B-mediated depolymerization. Overexpressed LlLIM1 significantly disturbed pollen tube growth and morphology, with multiple tubes protruding from one pollen grain and coaggregation of FM4-64-labeled vesicles and Golgi apparatuses at the subapex of the tube tip. Moderate expression of LlLIM1 induced an oscillatory formation of asterisk-shaped F-actin aggregates that oscillated with growth period but in different phases at the subapical region. These results suggest that the formation of LlLIM1-mediated overstabilized F-actin bundles interfered with endomembrane trafficking to result in growth retardation. Cosedimentation assays revealed that the binding affinity of LlLIM1 to F-actin was simultaneously regulated by both pH and Ca2+: LlLIM1 showed a preference for F-actin binding under low pH and low Ca2+ concentration. The potential functions of LlLIM1 as an ABP sensitive to pH and calcium in integrating endomembrane trafficking, oscillatory pH, and calcium circumstances to regulate tip-focused pollen tube growth are discussed.

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“…Weak severing activity is known for non-plant ADF/cofilin proteins (71). Severing has never been demonstrated directly for a plant ADF, although it is often inferred from depolymerization and polymerization assays (72,73). The relative contribution of severing versus enhancing the off-rate at pointed ends to ADF/ cofilin depolymerizing activity remains controversial (74 -76).…”

Section: Discussionmentioning

confidence: 99%

A Gelsolin-like Protein from Papaver rhoeas Pollen (PrABP80) Stimulates Calcium-regulated Severing and Depolymerization of Actin Filaments

Huang

Blanchoin

Chaudhry

et al. 2004

Journal of Biological Chemistry

104

110

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The cytoskeleton is a key regulator of plant morphogenesis, sexual reproduction, and cellular responses to extracellular stimuli. During the self-incompatibility response of Papaver rhoeas L. (field poppy) pollen, the actin filament network is rapidly depolymerized by a flood of cytosolic free Ca 2؉ that results in cessation of tip growth and prevention of fertilization. Attempts to model this dramatic cytoskeletal response with known pollen actin-binding proteins (ABPs) revealed that the major G-actin-binding protein profilin can account for only a small percentage of the measured depolymerization. We have identified an 80-kDa, Ca 2؉ -regulated ABP from poppy pollen (PrABP80) and characterized its biochemical properties in vitro. Sequence determination by mass spectrometry revealed that PrABP80 is related to gelsolin and villin. The molecular weight, lack of filament cross-linking activity, and a potent severing activity are all consistent with PrABP80 being a plant gelsolin. Kinetic analysis of actin assembly/disassembly reactions revealed that substoichiometric amounts of PrABP80 can nucleate actin polymerization from monomers, block the assembly of profilin-actin complex onto actin filament ends, and enhance profilin-mediated actin depolymerization. Fluorescence microscopy of individual actin filaments provided compelling, direct evidence for filament severing and confirmed the actin nucleation and barbed end capping properties. This is the first direct evidence for a plant gelsolin and the first example of efficient severing by a plant ABP. We propose that PrABP80 functions at the center of the selfincompatibility response by creating new filament pointed ends for disassembly and by blocking barbed ends from profilin-actin assembly.

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Interaction of elongation factor 1α from Zea mays (ZmEF‐1α) with F‐actin and interplay with the maize actin severing protein, ZmADF3

Cited by 28 publications

References 43 publications

UNC-87, a calponin-related protein in C. elegans, antagonizes ADF/cofilin-mediated actin filament dynamics

UNC-87, a calponin-related protein in C. elegans, antagonizes ADF/cofilin-mediated actin filament dynamics

An Actin-Binding Protein, LlLIM1, Mediates Calcium and Hydrogen Regulation of Actin Dynamics in Pollen Tubes

A Gelsolin-like Protein from Papaver rhoeas Pollen (PrABP80) Stimulates Calcium-regulated Severing and Depolymerization of Actin Filaments

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