12 research outputs found
Recent insights into the complexity of Tank-binding kinase 1 signaling networks: The emerging role of cellular localization in the activation and substrate specificity of TBK1
AbstractTank-binding kinase 1 (TBK1) serves as an important component of multiple signaling pathways. While the majority of research on TBK1 has focused on its role in innate immunity, critical functions for TBK1 in autophagy and cancer are beginning to emerge. This review highlights recent structural and biochemical studies that provide insights into the molecular mechanism of TBK1 activation and summarizes what is known to date about TBK1 substrate selection. Growing evidence suggests that both processes rely on TBK1 subcellular localization, with a variety of adaptor proteins each directing TBK1 to discrete signaling complexes for different cellular responses. Further study of TBK1-mediated pathways will require careful consideration of TBK1 mechanisms of activation and specificity for proper dissection of these distinct signaling cascades
Molecular determinants of origin discrimination by Orc1 initiators in archaea
Unlike bacteria, many eukaryotes initiate DNA replication from genomic sites that lack apparent sequence conservation. These loci are identified and bound by the origin recognition complex (ORC), and subsequently activated by a cascade of events that includes recruitment of an additional factor, Cdc6. Archaeal organisms generally possess one or more Orc1/Cdc6 homologs, belonging to the Initiator clade of ATPases associated with various cellular activities (AAA+) superfamily; however, these proteins recognize specific sequences within replication origins. Atomic resolution studies have shown that archaeal Orc1 proteins contact double-stranded DNA through an N-terminal AAA+ domain and a C-terminal winged-helix domain (WHD), but use remarkably few base-specific contacts. To investigate the biochemical effects of these associations, we mutated the DNA-interacting elements of the Orc1-1 and Orc1-3 paralogs from the archaeon Sulfolobus solfataricus, and tested their effect on origin binding and deformation. We find that the AAA+ domain has an unpredicted role in controlling the sequence selectivity of DNA binding, despite an absence of base-specific contacts to this region. Our results show that both the WHD and ATPase region influence origin recognition by Orc1/Cdc6, and suggest that not only DNA sequence, but also local DNA structure help define archaeal initiator binding sites
<i>N</i>-<i>tert</i>-Butoxycarbonyl‑<i>N</i>‑(2-(tritylthio)ethoxy)glycine as a Building Block for Peptide Ubiquitination
N-Boc-N-(2-(tritylthio)ethoxy)glycine
has been developed as a building block for peptide ubiquitination,
which is fully compatible with solid-phase Fmoc chemistry and common
peptide modifications including phosphorylation, methylation, acetylation,
biotinylation, and fluorescence labeling. The optimal conditions for
peptide cleavage and auxiliary removal were obtained. The utility
of this building block in peptide ubiquitination was demonstrated
by the synthesis of seven ubiquitinated histone and Tau peptides bearing
various modifications. Cys residues
were well tolerated and did not require orthogonal protection. The
structural integrity and folding of the synthesized ubiquitinated
peptides were confirmed by enzymatic deubiquitination of a fluorescently
labeled ubiquitin conjugate. The synthetic strategy using this building
block provides a practical approach for the preparation of ubiquitinated
peptides with diverse modifications
c-IAP1 and UbcH5 promote K11-linked polyubiquitination of RIP1 in TNF signalling
Canonical Lys48- and Lys63-linked as well as non-canonical linear polyubiquitin chains are involved in receptor-mediated NF-κB activation. This study identifies c-IAP1-generated Lys11-linked chains, so far implicated only in cell-cycle control and proteasome targeting, as an additional signal in this pathway