The extended AT-hook is a novel RNA binding motif

Michael Filarsky, Karina Zillner, Ingrid Araya, Ana Villar-Garea, Rainer Merkl, Gernot Längst & Attila Németh

RNA Biology
2015 vol: 12 issue: 8 pp: 864-876 doi: 10.1080/15476286.2015.1060394

Abstract
The AT-hook has been defined as a DNA binding peptide motif that contains a glycine-arginine-proline (G-R-P) tripeptide core flanked by basic amino acids. Recent reports documented variations in the sequence of AT-hooks and revealed RNA binding activity of some canonical AT-hooks, suggesting a higher structural and functional variability of this protein domain than previously anticipated. Here we describe the discovery and characterization of the extended AT-hook peptide motif (eAT-hook), in which basic amino acids appear symmetrical mainly at a distance of 12-15 amino acids from the G-R-P core. We identified 80 human and 60 mouse eAT-hook proteins and biochemically characterized the eAT-hooks of Tip5/BAZ2A, PTOV1 and GPBP1. Microscale thermophoresis and electrophoretic mobility shift assays reveal the nucleic acid binding features of this peptide motif, and show that eAT-hooks bind RNA with one order of magnitude higher affinity than DNA. In addition, cellular localization studies suggest a role for the N-terminal eAT-hook of PTOV1 in nucleocytoplasmic shuttling. In summary, our findings classify the eAT-hook as a novel nucleic acid binding motif, which potentially mediates various RNA-dependent cellular processes.

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Topics: AT-hook, GPBP1, Protein-RNA interaction, PTOV1, RNA-binding domain, Tip5, Monolith – MicroScale Thermophoresis, MST, Proteins, Publications