title: Zea mays Taxilin protein negatively regulates opaque-2 transcriptional activity by causing a change in its sub-cellular distribution.
abstract: Zea mays (maize) Opaque-2 (ZmO2) protein is an important bZIP transcription factor that regulates the expression of major storage proteins (22-kD zeins) and other important genes during maize seed development. ZmO2 is subject to functional regulation through protein-protein interactions. To unveil the potential regulatory network associated with ZmO2, a protein-protein interaction study was carried out using the truncated version of ZmO2 (O2-2) as bait in a yeast two-hybrid screen with a maize seed cDNA library. A protein with homology to Taxilin was found to have stable interaction with ZmO2 in yeast and was designated as ZmTaxilin. Sequence analysis indicated that ZmTaxilin has a long coiled-coil domain containing three conserved zipper motifs. Each of the three zipper motifs is individually able to interact with ZmO2 in yeast. A GST pull-down assay demonstrated the interaction between GST-fused ZmTaxilin and ZmO2 extracted from developing maize seeds. Using onion epidermal cells as in vivo assay system, we found that ZmTaxilin could change the sub-cellular distribution of ZmO2. We also demonstrated that this change significantly repressed the transcriptional activity of ZmO2 on the 22-kD zein promoter. Our study suggests that a Taxilin-mediated change in sub-cellular distribution of ZmO2 may have important functional consequences for ZmO2 activity.
authors.affiliation: Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Zhang
authors.forename: Zhenyi
authors.initials: Z
authors.lastname: Qiao
authors.forename: Zheng
authors.initials: Z
authors.lastname: Liang
authors.forename: Bing
authors.initials: B
authors.lastname: Mei
authors.forename: Zhengkai
authors.initials: Z
authors.lastname: Xu
authors.forename: Rentao
authors.initials: R
authors.lastname: Song
mesh_terms: D000595:Amino Acid Sequence; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation; D033921:Vesicular Transport Proteins / Q000235:genetics* / Q000378:metabolism; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism; D015028:Zein / Q000235:genetics* / Q000378:metabolism
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D010940:Plant Proteins; D014157:Transcription Factors; D033921:Vesicular Transport Proteins; C067402:opaque-2 protein, Zea mays; D015028:Zein