Genome-wide analysis of the plant-specific PLATZ proteins in maize and identification of their general role in interaction with RNA polymerase III complex.

BACKGROUND: PLATZ proteins are a novel class of plant-specific zinc-dependent DNA-binding proteins that are classified as transcription factors (TFs). However, their common biochemical features and functions are poorly understood.

RESULT: Here, we identified and cloned 17 PLATZ genes in the maize (Zea mays) genome. All ZmPLATZs were located in nuclei, consistent with their predicted role as TFs. However, none of ZmPLATZs was found to have intrinsic activation properties in yeast. Our recent work shows that FL3 (ZmPLATZ12) interacts with RPC53 and TFC1, two critical factors in the RNA polymerase III (RNAPIII) transcription complex. Using the yeast two-hybrid assay, we determined that seven other PLATZs interacted with both RPC53 and TFC1, whereas three had no protein-protein interaction with these two factors. The other six PLATZs interacted with either RPC53 or TFC1. These findings indicate that ZmPLATZ proteins are generally involved in the modulation of RNAPIII-mediated small non-coding RNA transcription. We also identified all of the PLATZ members in rice (Oryza sativa) and Arabidopsis thaliana and constructed a Maximum likelihood phylogenetic tree for ZmPLATZs. The resulting tree included 44 members and 5 subfamilies.

CONCLUSIONS: This study provides insight into understanding of the phylogenetic relationship, protein structure, expression pattern and cellular localization of PLATZs in maize. We identified nine and thirteen ZmPLATZs that have protein-protein interaction with RPC53 and TFC1 in the current study, respectively. Overall, the characterization and functional analysis of the PLATZ family in maize will pave the way to understanding RNAPIII-mediated regulation in plant development.