Structural highlights
Publication Abstract from PubMedFIC proteins regulate molecular processes from bacteria to humans by catalyzing post-translational modifications (PTM), the most frequent being the addition of AMP or AMPylation. In many AMPylating FIC proteins, a structurally conserved glutamate represses AMPylation and, in mammalian FICD, also supports deAMPylation of BiP/GRP78, a key chaperone of the unfolded protein response. Currently, a direct signal regulating these FIC proteins has not been identified. Here, we use X-ray crystallography and in vitro PTM assays to address this question. We discover that Enterococcus faecalis FIC (EfFIC) catalyzes both AMPylation and deAMPylation and that the glutamate implements a multi-position metal switch whereby Mg(2+) and Ca(2+) control AMPylation and deAMPylation differentially without a conformational change. Remarkably, Ca(2+) concentration also tunes deAMPylation of BiP by human FICD. Our results suggest that the conserved glutamate is a signature of AMPylation/deAMPylation FIC bifunctionality and identify metal ions as diffusible signals that regulate such FIC proteins directly. A Ca(2+)-regulated deAMPylation switch in human and bacterial FIC proteins.,Veyron S, Oliva G, Rolando M, Buchrieser C, Peyroche G, Cherfils J Nat Commun. 2019 Mar 8;10(1):1142. doi: 10.1038/s41467-019-09023-1. PMID:30850593[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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