The structure of phosphorylated P38γ is monomeric and reveals a conserved activation-loop conformation

AbstractBackground: Mitogen-activated protein (MAP) kinases mediate the cellular response to stimuli such as pro-inflammatory cytokines and environmental stress. P38γ is a new member of the MAP kinase family, and is expressed at its highest levels in skeletal muscle. P38γ is 63% identical in sequence to P38α. The structure of P38α MAP kinase has been determined in the apo, unphosphorylated, inactive form. The structures of apo unphosphorylated ERK2, a related MAP kinase, and apo phosphorylated ERK2 have also been determined.Results: We have determined the structure of doubly phosphorylated P38γ in complex with an ATP analog by X-ray crystallography. This is the first report of a structure of an activated kinase in the P38 subfamily, and the first bound to a nucleotide. P38γ residue phosphoryl-Thr183 forms hydrogen bonds with five basic amino acids, and these interactions induce an interdomain rotation. The conformation of the activation loop of P38γ is almost identical to that observed in the structure of activated ERK2. However, unlike ERK2, the crystal structure and solution studies indicate that activated P38γ exists as a monomer.Conclusions: Interactions mediated by phosphoryl-Thr183 induce structural changes that direct the domains and active-site residues of P38γ into a conformation consistent with catalytic activity. The conformation of the phosphorylation loop is likely to be similar in all activated MAP kinases, but not all activated MAP kinases form dimers

A Subset of Human Bromodomains Recognizes Butyryllysine and Crotonyllysine Histone Peptide Modifications

SummaryBromodomains are epigenetic readers that are recruited to acetyllysine residues in histone tails. Recent studies have identified non-acetyl acyllysine modifications, raising the possibility that these might be read by bromodomains. Profiling the nearly complete human bromodomain family revealed that while most human bromodomains bind only the shorter acetyl and propionyl marks, the bromodomains of BRD9, CECR2, and the second bromodomain of TAF1 also recognize the longer butyryl mark. In addition, the TAF1 second bromodomain is capable of binding crotonyl marks. None of the human bromodomains tested binds succinyl marks. We characterized structurally and biochemically the binding to different acyl groups, identifying bromodomain residues and structural attributes that contribute to specificity. These studies demonstrate a surprising degree of plasticity in some human bromodomains but no single factor controlling specificity across the family. The identification of candidate butyryl- and crotonyllysine readers supports the idea that these marks could have specific physiological functions

Decontamination of prions in a plasma product manufacturing environment

International audienceBackground: The high resistance of prions to inactivating treatments requires the proper management of decontaminating procedures of equipment in contact with materials of human or animal origin destined for medical purposes. Sodium hydroxide (NaOH) is widely used today for this purpose as it inactivates a wide variety of pathogens including prions. Study Design and Methods: Several NaOH treatments were tested on prions bound to either stainless steel or chromatographic resins in industrial conditions with multiple prion strains. Results: Data show a strong correlation between inactivation results obtained by immunochemical detection of the prion protein and those obtained with infectivity assays and establish effective inactivation treatments for prions bound to stainless steel or chromatographic resins (ion exchange and affinity), including treatments with lower NaOH concentrations. Furthermore, no obvious strain-specific behavior difference was observed between experimental models. Conclusion: The results generated by these investigations show that industrial NaOH decontamination regimens (in combination with the NaCl elution in the case of the chromatography process) attain substantial prion inactivation and/or removal between batches, thus providing added assurance to the biologic safety of the final plasma-derived medicinal products