A yeast two-hybrid screen in Arabidopsis thaliana suggests FORKED1 forms homodimers and the ARFA1 family has a role in cotyledon vein patterning

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Erickson, Jessica
University of Lethbridge. Faculty of Arts and Science
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Lethbridge, Alta. : University of Lethbridge, Department of Biological Sciences
The plant hormone auxin is essential for cell differentiation into vascular tissue, and leaf cells that will become veins show asymmetric distribution of the plasma membrane protein PINFORMED1 (PIN1), which directs auxin flux. The formation, sorting and transport of PIN1 vesicles within the endomembrane system leads to a high concentration of PIN1 on one membrane face. Many proteins involved in directing PIN1 to target membranes, including FORKED1 (FKD1). A yeast two-hybrid cDNA library screen was performed to identify protein interacters that might provide information about the molecular mechanism of FKD1. Results suggested that FKD1 is capable of forming homodimers through its DUF828 domain, but that this interaction depends on the absence of the 57 N-terminal amino acids. A second protein interacter was identified, ARFA1e, but later found to be a false positive. Despite the lack of interaction with FKD1, arfa1e-1 mutants displayed subtle vascular cotyledon phenotype characterized by increased vein number and increased vein meeting. The arfa1e-2 allele and mutants closely related genes (arfa1a and arfa1b) displayed similar defects. Double mutants showed an increase in phenotypic severity, supporting the notion that these proteins are acting redundantly during establishment of cotyledon vein pattern.
auxin , homodimers , cotyledon vein pattern , plasma membrane protein , PINFORMED1 , FORKED1 , DUF828 , ARFA1e protein , amino acids , vascular patterning