Organ polarity in Arabidopsis. NOZZLE physically interacts with members of the YABBY family.
Plant lateral organs exhibit proximal-distal and adaxial-abaxial polarity. In Arabidopsis, abaxial cell fate is regulated in part by putative transcription factors of the YABBY family, such as FILAMENTOUS FLOWER (FIL) and INNER NO OUTER (INO), by a mechanism that currently is not fully understood. NOZZLE (NZZ) encodes a plant-specific nuclear protein. Genetic evidence has shown that NZZ is involved in the positive feedback regulation of INO, thereby acting both as a temporal and spatial repressor of INO transcription. This mechanism allows the ovule primordium to complete its proximal-distal organization, prior to the onset of adaxial-abaxial development in the chalaza. During our study, we isolated FIL in a yeast two-hybrid screen using NZZ as bait. In vitro pull-down experiments confirmed the NZZ-FIL interaction. NZZ also bound INO and YABBY3, suggesting that NZZ generally interacts with YABBY proteins in vitro. The polar-charged region of NZZ was necessary and sufficient to bind to the zinc finger of INO and to interact with its C terminus carrying the high mobility group-like domain. We suggest that NZZ coordinates proximal-distal patterning and adaxial-abaxial polarity establishment in the developing ovule by directly binding to INO.
Institute of Plant Biology and Zürich-Basel Plant Science Center, University of Zürich, 8008 Zurich, Switzerland.
Patrick
P
Sieber
Michael
M
Petrascheck
Alcide
A
Barberis
Kay
K
Schneitz
D017360:Arabidopsis / Q000033:anatomy & histology* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D017931:DNA Primers; D035264:Flowers / Q000378:metabolism / Q000648:ultrastructure; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D016335:Zinc Fingers
D029681:Arabidopsis Proteins; D017931:DNA Primers; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C416221:SPL protein, Arabidopsis; C121842:YABBY3 protein, Arabidopsis