The auxin-binding protein 1 is essential for the control of cell cycle.
The phytohormone auxin has been known for >50 years to be required for entry into the cell cycle. Despite the critical effects exerted by auxin on the control of cell division, the molecular mechanism by which auxin controls this pathway is poorly understood, and how auxin is perceived upstream of any change in the cell cycle is unknown. Auxin Binding Protein 1 (ABP1) is considered to be a candidate auxin receptor, triggering early modification of ion fluxes across the plasma membrane in response to auxin. ABP1 has also been proposed to mediate auxin-dependent cell expansion, and is essential for early embryonic development. We investigated whether ABP1 has a role in the cell cycle. Functional inactivation of ABP1 in the model plant cell system BY2 was achieved through cellular immunization via the conditional expression of a single-chain fragment variable (scFv). This scFv was derived from a well characterized anti-ABP1 monoclonal antibody previously shown to block the activity of the protein. We demonstrate that functional inactivation of ABP1 results in cell-cycle arrest, and provide evidence that ABP1 plays a critical role in regulation of the cell cycle by acting at both the G1/S and G2/M checkpoints. We conclude that ABP1 is essential for the auxin control of cell division and is likely to constitute the first step of the auxin-signalling pathway mediating auxin effects on the cell cycle.
David
Karine M
KM
Institut des Sciences du Végétal, CNRS, 91198 Gif sur Yvette, France.
Couch
Daniel
D
Braun
Nils
N
Brown
Spencer
S
Grosclaude
Jeanne
J
Perrot-Rechenmann
Catherine
C
D000818:Animals; D002453:Cell Cycle / Q000502:physiology*; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D005434:Flow Cytometry; D016193:G1 Phase / Q000502:physiology; D016195:G2 Phase / Q000502:physiology; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D047468:Immunoprecipitation; D051379:Mice; D010940:Plant Proteins / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D030821:Plants, Genetically Modified; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D020349:Surface Plasmon Resonance; D014026:Nicotiana / Q000166:cytology / Q000235:genetics / Q000378:metabolism
D007135:Immunoglobulin Variable Region; D010940:Plant Proteins; D011956:Receptors, Cell Surface; C083846:auxin-binding protein 1