title: Structural basis of RNA binding by leucine zipper GCN4.
abstract: Recently, we showed that leucine zipper (LZ) motifs of basic leucine zipper (bZIP) transcription factors GCN4 and c-Jun are capable of catalyzing degradation of RNA (Nikolaev et al., PLoS ONE 2010; 5:e10765). This observation is intriguing given the tight regulation of RNA turnover control and the antiquity of bZIP transcription factors. To support further mechanistic studies, herein, we elucidated RNA binding interface of the GCN4 leucine zipper motif from yeast. Solution NMR experiments showed that the LZ-RNA interaction interface is located in the first two heptads of LZ moiety, and that only the dimeric (coiled coil) LZ conformation is capable of binding RNA. Site-directed mutagenesis of the LZ-GCN4 RNA binding interface showed that substrate binding is facilitated by lysine and arginine side chains, and that at least one nucleophilic residue is located in proximity to the RNA phosphate backbone. Further studies in the context of full-length bZIP factors are envisaged to address the biological relevance of LZ RNase activity.
authors.affiliation: Biozentrum of University Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland. yaroslav@trosy.com
authors.forename: Yaroslav
authors.initials: Y
authors.lastname: Nikolaev
authors.forename: Konstantin
authors.initials: K
authors.lastname: Pervushin
mesh_terms: D000595:Amino Acid Sequence; D050976:Basic-Leucine Zipper Transcription Factors / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D011487:Protein Conformation; D012313:RNA / Q000737:chemistry / Q000378:metabolism*; D012260:Ribonucleases / Q000737:chemistry / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; C501391:GCN4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D012313:RNA; D012260:Ribonucleases