PT  - JOURNAL ARTICLE
AU  - Hosoda, Kazuo
AU  - Imamura, Aya
AU  - Katoh, Etsuko
AU  - Hatta, Tomohisa
AU  - Tachiki, Mari
AU  - Yamada, Hisami
AU  - Mizuno, Takeshi
AU  - Yamazaki, Toshimasa
TI  - Molecular Structure of the GARP Family of Plant Myb-Related DNA Binding Motifs of the Arabidopsis Response Regulators
AID  - 10.1105/tpc.002733
DP  - 2002 Sep 01
TA  - The Plant Cell
PG  - 2015--2029
VI  - 14
IP  - 9
4099  - http://www.plantcell.org/content/14/9/2015.short
4100  - http://www.plantcell.org/content/14/9/2015.full
SO  - Plant Cell2002 Sep 01; 14
AB  - The B motif is a signature of type-B response regulators (ARRs) involved in His-to-Asp phosphorelay signal transduction systems in Arabidopsis. Homologous motifs occur widely in the GARP family of plant transcription factors. To gain general insight into the structure and function of B motifs (or GARP motifs), we characterized the B motif derived from a representative ARR, ARR10, which led to a number of intriguing findings. First, the B motif of ARR10 (named ARR10-B and extending from Thr-179 to Ser-242) possesses a nuclear localization signal, as indicated by the intracellular localization of a green fluorescent protein–ARR10-B fusion protein in onion epidermal cells. Second, the purified ARR10-B molecule binds specifically in vitro to DNA with the core sequence AGATT. This was demonstrated by several in vitro approaches, including PCR-assisted DNA binding site selection, gel retardation assays, and surface plasmon resonance analysis. Finally, the three-dimensional structure of ARR10-B in solution was determined by NMR spectroscopy, showing that it contains a helix-turn-helix structure. Furthermore, the mode of interaction between ARR10-B and the target DNA was assessed extensively by NMR spectroscopy. Together, these results lead us to propose that the mechanism of DNA recognition by ARR10-B is essentially the same as that of homeodomains. We conclude that the B motif is a multifunctional domain responsible for both nuclear localization and DNA binding and suggest that these insights could be applicable generally to the large GARP family of plant transcription factors.