The identification of DNA binding factors specific for as-1-like sequences in auxin-responsive regions of parA, parB and parC.
We have identified the auxin-responsive region (Aux-RR) of the parA promoter; it is derived from a gene that is induced by auxin in tobacco mesophyll protoplasts. By analyses of gain-of-function and point mutations in transgenic tobacco plants, we showed that an as-1-like sequence was required, but not alone sufficient, for auxin responsiveness of the parA promoter, as has been also shown for the parC promoter in a recent study. A gel mobility shift assay revealed that the as-1-like sequence of the parA promoter bound specifically to the as-1 binding nuclear factor, ASF-1, while the as-1-like sequence of the parC promoter bound specifically to a novel nuclear factor named ALF-1 (as-1-like sequence binding factor-1). Since these bindings were correlated with auxin-induced activation of transcription, those results suggest that ALF-1 is a new nuclear factor involved in auxin responsiveness and that it is distinct from ASF-1. Furthermore, we found that an as-1-like sequence in the AuxRR of parB bound specifically to a tobacco nuclear factor, named ALF-2, which differed from ASF-1 and ALF-1. These results suggest that the auxin responsiveness of the auxin-inducible genes parA, parB and parC are regulated by different mechanisms, even though the cis-acting elements look similar.
Sakai
T
T
Department of Biological Sciences, Graduate School of Science, University of Tokyo, Japan.
Takahashi
Y
Y
Nagata
T
T
D001483:Base Sequence; D018744:DNA, Plant; D004268:DNA-Binding Proteins / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism
D018744:DNA, Plant; D004268:DNA-Binding Proteins; D007210:Indoleacetic Acids; D009687:Nuclear Proteins; D010940:Plant Proteins