Characterization of the VIER F-BOX PROTEINE genes from Arabidopsis reveals their importance for plant growth and development.
E3 ubiquitin ligases (E3s) target proteins for degradation by the 26S proteasome. In SKP1/CDC53/F-box protein-type E3s, substrate specificity is conferred by the interchangeable F-box protein subunit. The vast majority of the 694 F-box proteins encoded by the Arabidopsis thaliana genome remain to be understood. We characterize the VIER F-BOX PROTEINE (VFB; German for FOUR F-BOX PROTEINS) genes from Arabidopsis that belong to subfamily C of the Arabidopsis F-box protein superfamily. This subfamily also includes the F-box proteins TRANSPORT INHIBITOR RESPONSE1 (TIR1)/AUXIN SIGNALING F-BOX (AFB) proteins and EIN3 BINDING F-BOX proteins, which regulate auxin and ethylene responses, respectively. We show that loss of VFB function causes delayed plant growth and reduced lateral root formation. We find that the expression of a number of auxin-responsive genes and the activity of DR5:beta-glucuronidase, a reporter for auxin response, are reduced in the vfb mutants. This finding correlates with an increase in the abundance of an AUXIN/INDOLE-3-ACETIC ACID repressor. However, we also find that auxin responses are not affected in the vfb mutants and that a representative VFB family member, VFB2, cannot functionally complement the tir1-1 mutant. We therefore exclude the possibility that VFBs are functional orthologs of TIR1/AFB proteins.
Schwager
Katja M
KM
Department of Developmental Genetics, Centre for Plant Molecular Biology, Tübingen University, 72076 Tübingen, Germany.
Calderon-Villalobos
Luz Irina A
LI
Dohmann
Esther M N
EM
Willige
Björn C
BC
Knierer
Stephan
S
Nill
Carola
C
Schwechheimer
Claus
C
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000145:classification / Q000235:genetics* / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics*; D001483:Base Sequence; D003062:Codon; D044783:F-Box Proteins / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D016296:Mutagenesis; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D018749:RNA, Plant / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D003062:Codon; D044783:F-Box Proteins; D018749:RNA, Plant