@article{1299944,

title = {A Tunable Brake for HECT Ubiquitin Ligases},

author = {Zan Chen and Hanjie Jiang and Wei Xu and Xiaoguang Li and Daniel R Dempsey and Xiangbin Zhang and Peter Devreotes and Cynthia Wolberger and L Mario Amzel and Sandra B Gabelli and Philip A Cole},

doi = {10.1016/j.molcel.2017.03.020},

issn = {1097-4164},

year  = {2017},

date = {2017-05-01},

journal = {Mol Cell},

volume = {66},

number = {3},

pages = {345-357.e6},

abstract = {The HECT E3 ligases ubiquitinate numerous transcription factors and signaling molecules, and their activity must be tightly controlled to prevent cancer, immune disorders, and other diseases. In this study, we have found unexpectedly that peptide linkers tethering WW domains in several HECT family members are key regulatory elements of their catalytic activities. Biochemical, structural, and cellular analyses have revealed that the linkers can lock the HECT domain in an inactive conformation and block the proposed allosteric ubiquitin binding site. Such linker-mediated autoinhibition of the HECT domain can be relieved by linker post-translational modifications, but complete removal of the brake can induce hyperactive autoubiquitination and E3 self destruction. These results clarify the mechanisms of several HECT protein cancer associated mutations and provide a new framework for understanding how HECT ubiquitin ligases must be finely tuned to ensure normal cellular behavior.},

keywords = {Allosteric Regulation, Endosomal Sorting Complexes Required for Transport, Enzyme Activation, Enzyme Stability, HeLa Cells, Humans, Models, Molecular, Mutation, Nedd4 Ubiquitin Protein Ligases, Phosphorylation, Post-Translational, Protein Domains, Protein Processing, Proteolysis, Repressor Proteins, Structure-Activity Relationship, Transfection, Ubiquitin-Protein Ligases},

pubstate = {published},

tppubtype = {article}

}

@article{1299945,

title = {Genetically encoded biosensors for visualizing live-cell biochemical activity at super-resolution},

author = {Gary C H Mo and Brian Ross and Fabian Hertel and Premashis Manna and Xinxing Yang and Eric Greenwald and Chris Booth and Ashlee M Plummer and Brian Tenner and Zan Chen and Yuxiao Wang and Eileen J Kennedy and Philip A Cole and Karen G Fleming and Amy Palmer and Ralph Jimenez and Jie Xiao and Peter Dedecker and Jin Zhang},

doi = {10.1038/nmeth.4221},

issn = {1548-7105},

year  = {2017},

date = {2017-04-01},

journal = {Nat Methods},

volume = {14},

number = {4},

pages = {427-434},

abstract = {Compartmentalized biochemical activities are essential to all cellular processes, but there is no generalizable method to visualize dynamic protein activities in living cells at a resolution commensurate with cellular compartmentalization. Here, we introduce a new class of fluorescent biosensors that detect biochemical activities in living cells at a resolution up to threefold better than the diffraction limit. These ’FLINC’ biosensors use binding-induced changes in protein fluorescence dynamics to translate kinase activities or protein-protein interactions into changes in fluorescence fluctuations, which are quantifiable through stochastic optical fluctuation imaging. A protein kinase A (PKA) biosensor allowed us to resolve minute PKA activity microdomains on the plasma membranes of living cells and to uncover the role of clustered anchoring proteins in organizing these activity microdomains. Together, these findings suggest that biochemical activities of the cell are spatially organized into an activity architecture whose structural and functional characteristics can be revealed by these new biosensors.},

keywords = {Biosensing Techniques, Cell Membrane, Cyclic AMP-Dependent Protein Kinases, Escherichia coli, Fluorescence Resonance Energy Transfer, Fluorescent Dyes, Green Fluorescent Proteins, HeLa Cells, Humans, Microscopy, Molecular Imaging, Mutagenesis, Protein Interaction Mapping, Site-Directed, Stochastic Processes},

pubstate = {published},

tppubtype = {article}

}