HypE-specific Nanobodies as Tools to modulate HypE-mediated Target AMPylation [Signal Transduction]

February 12th, 2015 by Truttmann, M. C., Wu, Q., Stiegeler, S., Duarte, J. N., Ingram, J., Ploegh, H. L.

The covalent addition of mono-AMP to target proteins (AMPylation) by Fic domain containing proteins is a poorly understood yet highly conserved post-translational modification. Here we describe the generation, evaluation and application of four HypE specific nanobodies, three of which inhibit HypE mediated target AMPylation in vitro, and a fourth that acts as an activator. All VHHs bind HypE when expressed as GFP-fusions in intact cells. We observe localization of HypE at the nuclear envelope and further identify histones H2 to H4, but not H1, as novel in vitro targets of the human Fic protein. Its role in histone modification provides a possible link between AMPylation and regulation of gene expression.