The Arabidopsis thaliana F-box protein FBL17 is essential for progression through the second mitosis during pollen development.
In fungi and metazoans, the SCF-type Ubiquitin protein ligases (E3s) play a critical role in cell cycle regulation by degrading negative regulators, such as cell cycle-dependent kinase inhibitors (CKIs) at the G1-to-S-phase checkpoint. Here we report that FBL17, an Arabidopsis thaliana F-box protein, is involved in cell cycle regulation during male gametogenesis. FBL17 expression is strongly enhanced in plants co-expressing E2Fa and DPa, transcription factors that promote S-phase entry. FBL17 loss-of-function mutants fail to undergo pollen mitosis II, which generates the two sperm cells in mature A. thaliana pollen. Nonetheless, the single sperm cell-like cell in fbl17 mutants is functional but will exclusively fertilize the egg cell of the female gametophyte, giving rise to an embryo that will later abort, most likely due to the lack of functional endosperm. Seed abortion can, however, be overcome by mutations in FIE, a component of the Polycomb group complex, overall resembling loss-of-function mutations in the A. thaliana cyclin-dependent kinase CDKA;1. Finally we identified ASK11, as an SKP1-like partner protein of FBL17 and discuss a possible mechanism how SCF(FBL17) may regulate cell division during male gametogenesis.
Gusti
Andi
A
Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg, France.
Baumberger
Nicolas
N
Nowack
Moritz
M
Pusch
Stefan
S
Eisler
Herfried
H
Potuschak
Thomas
T
De Veylder
Lieven
L
Schnittger
Arp
A
Genschik
Pascal
P
D017360:Arabidopsis / Q000196:embryology / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology; D044782:F-Box Motifs; D044783:F-Box Proteins / Q000502:physiology*; D005306:Fertilization; D018525:Germination; D006801:Humans; D008938:Mitosis / Q000502:physiology; D010447:Peptide Hydrolases / Q000378:metabolism; D011058:Pollen / Q000166:cytology / Q000254:growth & development*; D011499:Protein Processing, Post-Translational; D012097:Repressor Proteins / Q000502:physiology; D012639:Seeds; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000502:physiology; D054875:Ubiquitination
C541682:ASK11 protein, Arabidopsis; C532796:AT3G54650 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; D044783:F-Box Proteins; C118816:FIE protein, Arabidopsis; D012097:Repressor Proteins; D044767:Ubiquitin-Protein Ligases; D010447:Peptide Hydrolases