Dynamic assembly and disassembly of the actin cytoskeleton are crucial for polarized pollen tube growth. However, the molecular mechanisms underlying the dynamic disassembly and rapid turnover of the actin cytoskeleton remains largely unknown in pollen tubes. In the newly published paper, Dr. Huang and his colleagues discovered that the pollen specific Arabidopsis ADF7 prefers ADP-actin over ATP-actin and inhibits nucleotide exchange on actin as well as severs actin filaments, and is required for normal pollen tube growth. Importantly, they provide convincing evidence that ADF7 decorates filamentous actin, and demonstrate unambiguously that ADF7 promotes actin filaments turnover via its severing activity (Zheng et al., 2013, Plant Cell, 10.1105/tpc.113.117820). Thus, this study enriches our knowledge regarding the molecular mechanisms underlying the dynamic turnover of the actin cytoskeleton in pollen tubes, and provides insight into the regulation of polarized pollen tube growth.
Figure 1. ADF7 Promotes Actin Turnover via Severing Actin Filaments and Enhancing Monomer Off-rate
(A) Actin filaments dynamics in a wild-type pollen tube. (a) Filament severing events, (b) Filaments depolymerization.
(B) Actin filaments dynamics in an adf7 pollen tube. (a) Filament severing events, (b) Filaments depolymerization. Scale bar = 3 mm.
(C) Quantification of actin filaments dynamic parameters showed that the average severing frequency and monomer off-rate decreased in adf7 pollen tubes.
Dynamic assembly and disassembly of the actin cytoskeleton are crucial for polarized pollen tube growth. However, the molecular mechanisms underlying the dynamic disassembly and rapid turnover of the actin cytoskeleton remains largely unknown in pollen tubes. In the newly published paper, Dr. Huang and his colleagues discovered that the pollen specific Arabidopsis ADF7 prefers ADP-actin over ATP-actin and inhibits nucleotide exchange on actin as well as severs actin filaments, and is required for normal pollen tube growth. Importantly, they provide convincing evidence that ADF7 decorates filamentous actin, and demonstrate unambiguously that ADF7 promotes actin filaments turnover via its severing activity (Zheng et al., 2013, Plant Cell, 10.1105/tpc.113.117820). Thus, this study enriches our knowledge regarding the molecular mechanisms underlying the dynamic turnover of the actin cytoskeleton in pollen tubes, and provides insight into the regulation of polarized pollen tube growth.
Figure 1. ADF7 Promotes Actin Turnover via Severing Actin Filaments and Enhancing Monomer Off-rate
(A) Actin filaments dynamics in a wild-type pollen tube. (a) Filament severing events, (b) Filaments depolymerization.
(B) Actin filaments dynamics in an adf7 pollen tube. (a) Filament severing events, (b) Filaments depolymerization. Scale bar = 3 mm.
(C) Quantification of actin filaments dynamic parameters showed that the average severing frequency and monomer off-rate decreased in adf7 pollen tubes.