Substrate clustering potently regulates the activity of WW-HECT domain–containing ubiquitin ligases

AbstractUbiquitination-mediated proteolysis or regulation of proteins, ultimately executed by E3 ubiquitin ligases, control a wide array of cellular processes, including transcription, cell cycle, autophagy and apoptotic cell death. HECT-type E3 ubiquitin ligases can be distinguished from other subfamilies of E3 ubiquitin ligases because they have a C-terminal HECT domain that directly catalyzes the covalent attachment of ubiquitin to their substrate proteins. Deregulation of HECT-type E3-mediated ubiquitination plays a prominent role in cancer development and chemoresistance. Several members of this subfamily are indeed frequently deregulated in human cancers as a result of genetic mutations and altered expression or activity. HECT-type E3s contribute to tumorigenesis by regulating the ubiquitination rate of substrates that function as either tumour suppressors or oncogenes. While the pathological roles of the HECT family members in solid tumors are quite well established, their contribution to the pathogenesis of hematological malignancies has only recently emerged. This review aims to provide a comprehensive overview of the involvement of the HECT-type E3s in leukemogenesis.

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Control of the activity of WW‐HECT domain E3 ubiquitin ligases by NDFIP proteins

EMBO Reports ◽

10.1038/embor.2009.30 ◽

2009 ◽

Vol 10 (5) ◽

pp. 501-507 ◽

Cited By ~ 100

Author(s):

Thomas Mund ◽

Hugh R B Pelham

Keyword(s):

Ubiquitin Ligases ◽

E3 Ubiquitin Ligases ◽

Hect Domain

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Polyubiquitination by HECT E3s and the Determinants of Chain Type Specificity

Molecular and Cellular Biology ◽

10.1128/mcb.00240-09 ◽

2009 ◽

Vol 29 (12) ◽

pp. 3307-3318 ◽

Cited By ~ 159

Author(s):

Hyung Cheol Kim ◽

Jon M. Huibregtse

Keyword(s):

Saccharomyces Cerevisiae ◽

Amino Acids ◽

Ubiquitin Ligases ◽

Polyubiquitin Chain ◽

Polyubiquitin Chains ◽

Hect Domain ◽

E2 Protein ◽

Sequential Addition ◽

Chain Type

ABSTRACT Polyubiquitination can mediate several different biochemical functions, determined in part by which lysine of ubiquitin is used to link the polyubiquitin chain. Among the HECT domain ubiquitin ligases, some, such as human E6AP, preferentially catalyze the formation of K48-linked polyubiquitin chains, while others, including Saccharomyces cerevisiae Rsp5 and human Itch, preferentially catalyze the formation of K63-linked chains. The features of HECT E3s that determine their chain type specificities have not been identified. We show here that chain type specificity is a function solely of the Rsp5 HECT domain, that the identity of the cooperating E2 protein does not influence the chain type specificity, that single chains produced by Rsp5 contain between 12 and 30 ubiquitin moieties, and that the determinants of chain type specificity are located within the last 60 amino acids of the C lobe of the HECT domain. Our results are also consistent with a simple sequential-addition mechanism for polyubiquitination by Rsp5, rather than a mechanism involving the formation of either E2- or E3-linked polyubiquitin chain transfers.

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Degradation of the Tumor Suppressor Smad4 by WW and HECT Domain Ubiquitin Ligases

Journal of Biological Chemistry ◽

10.1074/jbc.m414027200 ◽

2005 ◽

Vol 280 (23) ◽

pp. 22115-22123 ◽

Cited By ~ 128

Author(s):

Anita Morén ◽

Takeshi Imamura ◽

Kohei Miyazono ◽

Carl-Henrik Heldin ◽

Aristidis Moustakas

Keyword(s):

Transforming Growth Factor ◽

Direct Interaction ◽

Ubiquitin Ligases ◽

Transforming Growth Factor Β ◽

Down Regulation ◽

Peripheral Cell ◽

Hect Domain ◽

E3 Ligases ◽

Mechanism Of Degradation ◽

Signaling Receptors

Smad4 mediates signaling by the transforming growth factor-β (TGF-β) superfamily of cytokines. Smad signaling is negatively regulated by inhibitory (I) Smads and ubiquitin-mediated processes. Known mechanisms of proteasomal degradation of Smads depend on the direct interaction of specific E3 ligases with Smads. Alternatively, I-Smads elicit degradation of the TGF-β receptor by recruiting the WW and HECT domain E3 ligases, Smurfs, WWP1, or NEDD4–2. We describe an equivalent mechanism of degradation of Smad4 by the above E3 ligases, via formation of ternary complexes between Smad4 and Smurfs, mediated by R-Smads (Smad2) or I-Smads (Smad6/7), acting as adaptors. Smurfs, which otherwise cannot directly bind to Smad4, mediated poly-ubiquitination of Smad4 in the presence of Smad6 or Smad7. Smad4 co-localized with Smad7 and Smurf1 primarily in the cytoplasm and in peripheral cell protrusions. Smad2 or Smad7 mutants defective in Smad4 interaction failed to induce Smurf1-mediated down-regulation of Smad4. A Smad4 mutant defective in Smad2 or Smad7 interaction could not be effectively down-regulated by Smurf1. We propose that Smad4 is targeted for degradation by multiple ubiquitin ligases that can simultaneously act on R-Smads and signaling receptors. Such mechanisms of down-regulation of TGF-β signaling may be critical for proper physiological response to this pathway.

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Faculty Opinions recommendation of Different HECT domain ubiquitin ligases employ distinct mechanisms of polyubiquitin chain synthesis.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1030176.358430 ◽

2006 ◽

Author(s):

Jane Endicott

Keyword(s):

Ubiquitin Ligases ◽

Polyubiquitin Chain ◽

Hect Domain ◽

Chain Synthesis

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Structural mechanisms of HECT-type ubiquitin ligases

Biological Chemistry ◽

10.1515/hsz-2017-0184 ◽

2018 ◽

Vol 399 (2) ◽

pp. 127-145 ◽

Cited By ~ 43

Author(s):

Sonja Lorenz

Keyword(s):

Ubiquitin Ligases ◽

Structural Level ◽

Hect Domain ◽

Target Proteins ◽

Structural And Functional Properties ◽

E2 Enzymes ◽

Key Aspects ◽

Structural Mechanisms ◽

Regulatory Functions ◽

Structural Insights

AbstractUbiquitin ligases (E3 enzymes) transfer ubiquitin from ubiquitin-conjugating (E2) enzymes to target proteins. By determining the selection of target proteins, modification sites on those target proteins, and the types of ubiquitin modifications that are formed, E3 enzymes are key specificity factors in ubiquitin signaling. Here, I summarize our knowledge of the structural mechanisms in the HECT E3 subfamily, many members of which play important roles in human disease. I discuss interactions of the conserved HECT domain with E2 enzymes, ubiquitin and target proteins, as well as macromolecular interactions with regulatory functions. While we understand individual steps in the catalytic cycle of HECT E3 enzymes on a structural level, this review also highlights key aspects that have yet to be elucidated. For instance, it remains unclear how diverse target proteins are presented to the catalytic center and how certain HECT E3 enzymes achieve specificity in ubiquitin linkage formation. The structural and functional properties of the N-terminal regions of HECT E3 enzymes that likely act as signaling hubs are also largely unknown. Structural insights into these aspects may open up routes for a therapeutic intervention with specific HECT E3 functions in distinct pathophysiological settings.

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