scholarly journals OsFH3 Encodes a Type II Formin Required for Rice Morphogenesis

2021 ◽  
Vol 22 (24) ◽  
pp. 13250
Shuwei Chang ◽  
Zhanhong Ren ◽  
Chang Liu ◽  
Pingzhou Du ◽  
Jingbin Li ◽  

The actin cytoskeleton is crucial for plant morphogenesis, and organization of actin filaments (AF) is dynamically regulated by actin-binding proteins. However, the roles of actin-binding proteins, particularly type II formins, in this process remain poorly understood in plants. Here, we report that a type II formin in rice, Oryza sativa formin homolog 3 (OsFH3), acts as a major player to modulate AF dynamics and contributes to rice morphogenesis. osfh3 mutants were semi-dwarf with reduced size of seeds and unchanged responses to light or gravity compared with mutants of osfh5, another type II formin in rice. osfh3 osfh5 mutants were dwarf with more severe developmental defectiveness. Recombinant OsFH3 could nucleate actin, promote AF bundling, and cap the barbed end of AF to prevent elongation and depolymerization, but in the absence of profilin, OsFH3 could inhibit AF elongation. Different from other reported type II formins, OsFH3 could bind, but not bundle, microtubules directly. Furthermore, its N-terminal phosphatase and tensin homolog domain played a key role in modulating OsFH3 localization at intersections of AF and punctate structures of microtubules, which differed from other reported plant formins. Our results, thus, provide insights into the biological function of type II formins in modulating plant morphology by acting on AF dynamics.

1987 ◽  
Vol 104 (4) ◽  
pp. 1005-1017 ◽  
DL Stokes ◽  
DJ DeRosier

Previous studies demonstrated that actin filaments have variable twist in which the intersubunit angles vary by approximately +/- 10 degrees within a filament. In this work we show that this variability was unchanged when different methods were used to prepare filaments for electron microscopy. We also show that actin-binding proteins can modulate the variability in twist. Three preparations of actin filaments were photographed in the electron microscope: negatively stained filaments, replicas of rapidly frozen, etched filaments, and frozen hydrated filaments. In addition, micrographs of actin + tropomyosin + troponin (thin filaments), of actin + myosin S1 (decorated filaments), and of filaments frayed from the acrosomal process of Limulus sperm (Limulus filaments) were obtained. We used two independent methods to measure variable twist based on Fourier transforms of single filaments. The first involved measuring layer line intensity versus filament length and the second involved measuring layer line position. We measured a variability in the intersubunit angle of actin filaments of approximately 12 degrees independent of the method of preparation or of measurement. Thin filaments have 15 degrees of variability, but the increase over pure actin is not statistically significant. Decorated filaments and Limulus filaments, however, have significantly less variability (approximately 2 and 1 degree, respectively), indicating a torsional stiffening relative to actin. The results from actin alone using different preparative methods are evidence that variable twist is a property of actin in solution. The results from actin filaments in the presence of actin-binding proteins suggest that the angular variability can be modulated, depending on the biological function.

2006 ◽  
Vol 39 ◽  
pp. S240
M. Bathe ◽  
M. Claessens ◽  
E. Frey ◽  
A. Bausch

2007 ◽  
Vol 36 (1) ◽  
pp. 121-125 ◽  
Ricardo Uribe ◽  
David Jay

2011 ◽  
Vol 100 (3) ◽  
pp. 106a-107a
María del Rocío Cantero ◽  
Horacio F. Cantiello

1996 ◽  
Vol 325 (2) ◽  
pp. 183-189 ◽  
K.-P. Janssen ◽  
L. Eichinger ◽  
P.A. Janmey ◽  
A.A. Noegel ◽  
M. Schliwa ◽  

1988 ◽  
Vol 9 (4-5) ◽  
pp. 521-530 ◽  
Michael Schleicher ◽  
Elisabeth André ◽  
Herbert Hartmann ◽  
Angelika A. Noegel

1994 ◽  
Vol 125 (2) ◽  
pp. 381-391 ◽  
J Mulholland ◽  
D Preuss ◽  
A Moon ◽  
A Wong ◽  
D Drubin ◽  

We characterized the yeast actin cytoskeleton at the ultrastructural level using immunoelectron microscopy. Anti-actin antibodies primarily labeled dense, patchlike cortical structures and cytoplasmic cables. This localization recapitulates results obtained with immunofluorescence light microscopy, but at much higher resolution. Immuno-EM double-labeling experiments were conducted with antibodies to actin together with antibodies to the actin binding proteins Abp1p and cofilin. As expected from immunofluorescence experiments, Abp1p, cofilin, and actin colocalized in immuno-EM to the dense patchlike structures but not to the cables. In this way, we can unambiguously identify the patches as the cortical actin cytoskeleton. The cortical actin patches were observed to be associated with the cell surface via an invagination of plasma membrane. This novel cortical cytoskeleton-plasma membrane interface appears to consist of a fingerlike invagination of plasma membrane around which actin filaments and actin binding proteins are organized. We propose a possible role for this unique cortical structure in wall growth and osmotic regulation.

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