Distribution and diversity of classical deacylases in bacteria.

Classical Zn-dependent deac(et)ylases play fundamental regulatory roles in life and are well characterized in eukaryotes regarding their structures, substrates and physiological roles. In bacteria, however, classical deacylases are less well understood. We construct a Generalized Profile (GP) and identify thousands of uncharacterized classical deacylases in bacteria, which are grouped into five clusters.

Lane formation in gravitationally driven colloid mixtures consisting of up to three different particle sizes.

Brownian dynamics simulations are utilized to study segregation phenomena far from thermodynamic equilibrium. In the present study, we expand upon the analysis of binary colloid mixtures and introduce a third particle species to further our understanding of colloidal systems. Gravitationally driven, spherical colloids immersed in an implicit solvent are confined in two-dimensional linear microchannels.

ERLIN1/2 scaffolds bridge TMUB1 and RNF170 and restrict cholesterol esterification to regulate the secretory pathway.

Complexes of ERLIN1 and ERLIN2 (ER lipid raft-associated 1 and 2) form large ring-like cup-shaped structures on the endoplasmic reticulum (ER) membrane and serve as platforms to bind cholesterol and E3 ubiquitin ligases, potentially defining functional nanodomains. Here, we show that ERLIN scaffolds mediate the interaction between the full-length isoform of TMUB1 (transmembrane and ubiquitin-like domain-containing 1) and RNF170 (RING finger protein 170). We identify a luminal N-terminal conserved region in TMUB1 and RNF170, which is required for this interaction.

Beyond the C-terminal Glycine of ATG8 Proteins - The Story of Some Neglected Amino Acids.

ATG8 proteins form a family of small ubiquitin-like modifiers, well-known for their importance in both macroautophagy and autophagy-independent processes. A unique feature of this protein family is their conjugation to membrane lipids through the covalent attachment of a glycine residue at the C-terminus of ATG8 proteins. Notably, most ATG8 proteins are expressed with additional amino acids at their C-terminus, shielding the key glycine residue.

N4BP1 functions as a dimerization-dependent linear ubiquitin reader which regulates TNF signalling.

Signalling through TNFR1 modulates proinflammatory gene transcription and programmed cell death, and its impairment causes autoimmune diseases and cancer. NEDD4-binding protein 1 (N4BP1) is a critical suppressor of proinflammatory cytokine production that acts as a regulator of innate immune signalling and inflammation. However, our current understanding about the molecular properties that enable N4BP1 to exert its suppressive potential remain limited.

Cytoplasmic calcium influx mediated by plant MLKLs confers TNL-triggered immunity.

The plant homolog of vertebrate necroptosis inducer mixed-lineage kinase domain-like (MLKL) contributes to downstream steps in Toll-interleukin-1 receptor domain NLR (TNL)-receptor-triggered immunity. Here, we show that Arabidopsis MLKL1 (AtMLKL1) clusters into puncta at the plasma membrane upon TNL activation and that this sub-cellular reorganization is dependent on the TNL signal transducer, EDS1. We find that AtMLKLs confer TNL-triggered immunity in parallel with RPW8-type HeLo-domain-containing NLRs (RNLs) and that the AtMLKL N-terminal HeLo domain is indispensable for both immunity and clustering.

The structural basis for deubiquitination by the fingerless USP-type effector TssM.

Intracellular bacteria are threatened by ubiquitin-mediated autophagy, whenever the bacterial surface or enclosing membrane structures become targets of host ubiquitin ligases. As a countermeasure, many intracellular pathogens encode deubiquitinase (DUB) effectors to keep their surfaces free of ubiquitin. Most bacterial DUBs belong to the OTU or CE-clan families.

The FAM104 proteins VCF1/2 promote the nuclear localization of p97/VCP.

The ATPase p97 (also known as VCP, Cdc48) has crucial functions in a variety of important cellular processes such as protein quality control, organellar homeostasis, and DNA damage repair, and its de-regulation is linked to neuromuscular diseases and cancer. p97 is tightly controlled by numerous regulatory cofactors, but the full range and function of the p97-cofactor network is unknown. Here, we identify the hitherto uncharacterized FAM104 proteins as a conserved family of p97 interactors.

Lysine deserts prevent adventitious ubiquitylation of ubiquitin-proteasome components.

In terms of its relative frequency, lysine is a common amino acid in the human proteome. However, by bioinformatics we find hundreds of proteins that contain long and evolutionarily conserved stretches completely devoid of lysine residues. These so-called lysine deserts show a high prevalence in intrinsically disordered proteins with known or predicted functions within the ubiquitin-proteasome system (UPS), including many E3 ubiquitin-protein ligases and UBL domain proteasome substrate shuttles, such as BAG6, RAD23A, UBQLN1 and UBQLN2.

The moonlighting of RAD23 in DNA repair and protein degradation.

A moonlighting protein is one, which carries out multiple, often wholly unrelated, functions. The RAD23 protein is a fascinating example of this, where the same polypeptide and the embedded domains function independently in both nucleotide excision repair (NER) and protein degradation via the ubiquitin-proteasome system (UPS). Hence, through direct binding to the central NER component XPC, RAD23 stabilizes XPC and contributes to DNA damage recognition.

A widely distributed family of eukaryotic and bacterial deubiquitinases related to herpesviral large tegument proteins.

Distinct families of eukaryotic deubiquitinases (DUBs) are regulators of ubiquitin signaling. Here, we report on the presence of an additional DUB class broadly distributed in eukaryotes and several bacteria. The only described members of this family are the large tegument proteins of herpesviruses, which are attached to the outside of the viral capsid.

Bioinformatical Approaches to the Discovery and Classification of Novel Deubiquitinases.

Deubiquitinating enzymes (DUBs) are active at multiple levels of the eukaryotic ubiquitin system. DUBs are important for ubiquitin activation and maintaining cellular ubiquitin levels but can also edit or dissolve ubiquitin chains or deconjugate ubiquitin from substrates. Eukaryotic DUBs can be grouped into seven molecular classes, most of which enzymes are cysteine proteases assuming the papain fold.

Cln5 represents a new type of cysteine-based -depalmitoylase linked to neurodegeneration.

Genetic variants are associated with childhood neurodegeneration and Alzheimer's disease; however, the molecular function of ceroid lipofuscinosis neuronal protein 5 (Cln5) is unknown. We solved the Cln5 crystal structure and identified a region homologous to the catalytic domain of members of the N1pC/P60 superfamily of papain-like enzymes. However, we observed no protease activity for Cln5; and instead, we discovered that Cln5 and structurally related PPPDE1 and PPPDE2 have efficient cysteine palmitoyl thioesterase (-depalmitoylation) activity using fluorescent substrates.

Bacterial ribosome collision sensing by a MutS DNA repair ATPase paralogue.

Ribosome stalling during translation is detrimental to cellular fitness, but how this is sensed and elicits recycling of ribosomal subunits and quality control of associated mRNA and incomplete nascent chains is poorly understood. Here we uncover Bacillus subtilis MutS2, a member of the conserved MutS family of ATPases that function in DNA mismatch repair, as an unexpected ribosome-binding protein with an essential function in translational quality control. Cryo-electron microscopy analysis of affinity-purified native complexes shows that MutS2 functions in sensing collisions between stalled and translating ribosomes and suggests how ribosome collisions can serve as platforms to deploy downstream processes: MutS2 has an RNA endonuclease small MutS-related (SMR) domain, as well as an ATPase/clamp domain that is properly positioned to promote ribosomal subunit dissociation, which is a requirement both for ribosome recycling and for initiation of ribosome-associated protein quality control (RQC).

A structural basis for the diverse linkage specificities within the ZUFSP deubiquitinase family.

Eukaryotic deubiquitinases are important regulators of ubiquitin signaling and can be subdivided into several structurally distinct classes. The ZUFSP family, with ZUP1 as its sole human member, has a modular architecture with a core catalytic domain highly active against the ubiquitin-derived peptide RLRGG, but not against ubiquitin itself. Ubiquitin recognition is conferred by additional non-catalytic domains, making full-length ZUP1 active against long K63-linked chains.

Discovery of a Family of Mixed Lineage Kinase Domain-like Proteins in Plants and Their Role in Innate Immune Signaling.

HeLo domain-containing mixed lineage kinase domain-like protein (MLKL), a pseudokinase, mediates necroptotic cell death in animals. Here, we report the discovery of a conserved protein family across seed plants that structurally resembles vertebrate MLKL. The Arabidopsis genome encodes three MLKLs (AtMLKLs) with overlapping functions in disease resistance mediated by Toll-interleukin 1-receptor domain intracellular immune receptors (TNLs).

An evolutionarily distinct chaperone promotes 20S proteasome α-ring assembly in plants.

The core protease (CP) subcomplex of the 26S proteasome houses the proteolytic active sites and assumes a barrel shape comprised of four co-axially stacked heptameric rings formed by structurally related α- and β-subunits. CP biogenesis typically begins with the assembly of the α-ring, which then provides a template for β-subunit integration. In eukaryotes, α-ring assembly is partially mediated by two hetero-dimeric chaperones, termed Pba1-Pba2 (Add66) and Pba3-Pba4 (also known as Irc25-Poc4) in yeast.

Proteasomal degradation induced by DPP9-mediated processing competes with mitochondrial protein import.

Plasticity of the proteome is critical to adapt to varying conditions. Control of mitochondrial protein import contributes to this plasticity. Here, we identified a pathway that regulates mitochondrial protein import by regulated N-terminal processing.

An evolutionary approach to systematic discovery of novel deubiquitinases, applied to .

Deubiquitinating enzymes (DUBs) are important regulators of the posttranslational protein ubiquitination system. Mammalian genomes encode about 100 different DUBs, which can be grouped into seven different classes. Members of other DUB classes are found in pathogenic bacteria, which use them to target the host defense.

Identification and characterization of diverse OTU deubiquitinases in bacteria.

Manipulation of host ubiquitin signaling is becoming an increasingly apparent evolutionary strategy among bacterial and viral pathogens. By removing host ubiquitin signals, for example, invading pathogens can inactivate immune response pathways and evade detection. The ovarian tumor (OTU) family of deubiquitinases regulates diverse ubiquitin signals in humans.