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. 2023 Dec 31;18(1):2092346.
doi: 10.1080/15592324.2022.2092346. Epub 2022 Jun 26.

Phosphatidic acid inhibits SCAB1-mediated F-actin bundling in Arabidopsis

Haiqi Fu  1 , Xinhao Yang  1 , Rong Hao  1 , Xiuli Han  1 , Shu Song  1 , Yan Guo  1 , Yongqing Yang  1
Affiliations

Phosphatidic acid inhibits SCAB1-mediated F-actin bundling in Arabidopsis

Haiqi Fu et al. Plant Signal Behav. .

Abstract

Stomatal closure-associated actin-binding protein 1 (SCAB1) regulates stomatal closure by mediating actin filament reorganization in Arabidopsis thaliana. Our previous study showed that phosphatidylinositol 3-phosphate (PI3P) binds to SCAB1 and inhibits its oligomerization, thereby inhibiting its activity on F-actin in guard cells during stomatal closure. In this study, we show that another phospholipid, phosphatidic acid (PA), also binds to SCAB1 and inhibits its actin-bundling activity but not its actin-binding activity. F-actin bundling was promoted in vivo by treating Col-0 seedlings with n-butanol, a suppressor of PA production, but this effect was absent in the scab1 mutant. These results indicate that the signaling molecule PA is involved in the modulation of SCAB1 activity in F-actin reorganization.

Keywords: Arabidopsis thaliana; F-actin bundling; PA; SCAB1.

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Conflict of interest statement

No potential conflict of interest was reported by the author(s).

Figures

Figure 1.
Figure 1.
PA binds to SCAB1. A, SCAB1 binds to PA in a protein-lipid overlay assay. Hydrophobic membranes spotted with different concentrations (1, 2, 5, and 10 nM) of PA or PI4P (control) were incubated with 1 μg/mL purified SCAB1 and immunoblotted with anti-GST antibodies. PA was dissolved in methanol.
Figure 2.
Figure 2.
(a) Low-speed co-sedimentation assays of SCAB1 with F-actin. Preassembled F-actin was incubated with SCAB1 (1 μM) treated with or without 20 μM PA. SCAB1 and F-actin were centrifugated at 5,000 g for 30 min and analyzed by SDS-PAGE. (b) High-speed co-sedimentation assays of SCAB1 with F-actin. Preassembled F-actin was incubated with SCAB1 (1 μM) treated with or without 20 μM PA. SCAB1 and F-actin were centrifugated at 100,000 g for 30 min and analyzed by SDS-PAGE.
Figure 3.
Figure 3.
Confocal images of fABD2-GFP-labeled microfilaments (MFs) in hypocotyl epidermal cells in the wild type (Col-0) or scab1 background. Six-day-old transgenic fABD2-GFP/Col-0 and fABD2-GFP/scab1 seedlings were treated in liquid MS medium with (top) or without (middle) 0.4% (v/v) n-butanol for 24 h. MS medium with 0.4% (v/v) 2-butanol (bottom) was used as a control. Scale bars, 25 μm.
See this image and copyright information in PMC

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