PE/PPE Proteome and ESX-5 Substrate Spectrum in .

PE/PPE proteins secreted by the ESX-5 type VII secretion system constitute a major protein repertoire in pathogenic mycobacteria and are essential for bacterial survival, pathogenicity, and host-pathogen interaction; however, little is known about their expression and secretion. The scarcity of arginine and lysine residues in PE/PPE protein sequences and the high homology of their N-terminal domains limit protein identification using classical trypsin-based proteomic methods. This study used endoproteinase AspN and trypsin to characterize the proteome of Twenty-seven PE/PPE proteins were uniquely identified in AspN digests, especially PE_PGRS proteins.

Structural insights into the assembly pathway of the Helicobacter pylori CagT4SS outer membrane core complex.

Cag type IV secretion system (CagT4SS) translocates oncoprotein cytotoxin-associated gene A (CagA) into host cells and plays a key role in the pathogenesis of Helicobacter pylori. The structure of the outer membrane core complex (OMCC) in CagT4SS consists of CagX, CagY, CagM, CagT, and Cag3 in a stoichiometric ratio of 1:1:2:2:5 with 14-fold symmetry. However, the assembly pathway of OMCC remains elusive.

Cryo-EM structures of ClC-2 chloride channel reveal the blocking mechanism of its specific inhibitor AK-42.

ClC-2 transports chloride ions across plasma membranes and plays critical roles in cellular homeostasis. Its dysfunction is involved in diseases including leukodystrophy and primary aldosteronism. AK-42 was recently reported as a specific inhibitor of ClC-2.

Comparative Genomics Reveals Insights into the Divergent Evolution of Astigmatic Mites and Household Pest Adaptations.

Highly diversified astigmatic mites comprise many medically important human household pests such as house dust mites causing ∼1-2% of all allergic diseases globally; however, their evolutionary origin and diverse lifestyles including reversible parasitism have not been illustrated at the genomic level, which hampers allergy prevention and our exploration of these household pests. Using six high-quality assembled and annotated genomes, this study not only refuted the monophyly of mites and ticks, but also thoroughly explored the divergence of Acariformes and the diversification of astigmatic mites. In monophyletic Acariformes, Prostigmata known as notorious plant pests first evolved, and then rapidly evolving Astigmata diverged from soil oribatid mites.

Cryo-electron Tomography Reveals the Roles of FliY in Flagellar Motor Assembly.

Helicobacter pylori plays a causative role in gastric diseases. The pathogenicity of H. pylori depends on its ability to colonize the stomach guided by motility.

RNA mA methylation regulates dissemination of cancer cells by modulating expression and membrane localization of β-catenin.

N6-methyladenosine (mA) methylation, which is modified by the METTL3/METTL14 complex, is a dominant internal modification in mammalian RNA and tightly linked to cancer progression. Here we reveal that METTL3-promoted cell migration, invasion, and epithelial-to-mesenchymal transition (EMT) are associated with expression and membrane localization of β-catenin (encoded by CTNNB1), as opposed to Wnt signaling activation in various types of cancer cells, including cervical, lung, and liver cancer. Specifically, METTL3 regulates the transcription, mRNA decay, translation, and subcellular localization of β-catenin.

Mining of linear B cell epitopes of SARS-CoV-2 ORF8 protein from COVID-19 patients.

Given the on-going SARS-CoV-2 pandemic, identification of immunogenic targets against the viral protein will provide crucial advances towards the development of sensitive diagnostic tools and vaccination strategies. Our previous study has found that ORF8 protein of SARS-CoV-2 is highly immunogenic and shows high sensitivity in identifying COVID-19 disease. In this study, by employing overlapping linear peptides, we characterized the IgG immunodominant regions on SARS-CoV-2 ORF8 protein that are seropositive in the sera from SARS-CoV-2-infected patients.

Structure of mouse cytosolic sulfotransferase SULT2A8 provides insight into sulfonation of 7α-hydroxyl bile acids.

Cytosolic sulfotransferases (SULTs) catalyze the transfer of a sulfonate group from the cofactor 3'-phosphoadenosine 5'-phosphosulfate to a hydroxyl (OH) containing substrate and play a critical role in the homeostasis of endogenous compounds, including hormones, neurotransmitters, and bile acids. In human, SULT2A1 sulfonates the 3-OH of bile acids; however, bile acid metabolism in mouse is dependent on a 7α-OH sulfonating SULT2A8 via unknown molecular mechanisms. In this study, the crystal structure of SULT2A8 in complex with adenosine 3',5'-diphosphate and cholic acid was resolved at a resolution of 2.

Accurate Diagnosis of COVID-19 by a Novel Immunogenic Secreted SARS-CoV-2 orf8 Protein.

An accurate diagnostic test for early severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is the key weapon to control the coronavirus disease 2019 (COVID-19) pandemic. We previously reported that the SARS-CoV-2 genome contains a unique orf8 accessory gene absent from other human-pathogenic coronaviruses. Here, we characterized the SARS-CoV-2 orf8 as a novel immunogenic secreted protein and utilized it for the accurate diagnosis of COVID-19.

Crystal Structure of Flagellar Export Chaperone FliS in Complex With Flagellin and HP1076 of .

Functional flagella formation is a widespread virulence factor that plays a critical role in survival and host colonization. Flagellar synthesis is a complex and highly coordinated process. The assembly of the axial structure beyond the cell membrane is mediated by export chaperone proteins that transport their cognate substrates to the export gate complex.

Modular enzyme assembly for enhanced cascade biocatalysis and metabolic flux.

Enzymatic reactions in living cells are highly dynamic but simultaneously tightly regulated. Enzyme engineers seek to construct multienzyme complexes to prevent intermediate diffusion, to improve product yield, and to control the flux of metabolites. Here we choose a pair of short peptide tags (RIAD and RIDD) to create scaffold-free enzyme assemblies to achieve these goals.

Synthetic Multienzyme Complexes, Catalytic Nanomachineries for Cascade Biosynthesis .

Multienzyme complexes, or metabolons, are assemblies or clusters of sequential enzymes that naturally exist in metabolic pathways. These nanomachineries catalyze the conversion of metabolites more effectively than the freely floating enzymes by minimizing the diffusion of intermediates . Bioengineers have devised synthetic versions of multienzyme complexes in cells to synergize heterologous biosynthesis, to improve intracellular metabolic flux, and to achieve higher titer of valuable chemical products.

Cryo-EM structures of vacuolating cytotoxin A oligomeric assemblies at near-atomic resolution.

Human gastric pathogen () is the primary risk factor for gastric cancer and is one of the most prevalent carcinogenic infectious agents. Vacuolating cytotoxin A (VacA) is a key virulence factor secreted by and induces multiple cellular responses. Although structural and functional studies of VacA have been extensively performed, the high-resolution structure of a full-length VacA protomer and the molecular basis of its oligomerization are still unknown.

Three SpoA-domain proteins interact in the creation of the flagellar type III secretion system in .

Bacterial flagella are rotary nanomachines that contribute to bacterial fitness in many settings, including host colonization. The flagellar motor relies on the multiprotein flagellar motor-switch complex to govern flagellum formation and rotational direction. Different bacteria exhibit great diversity in their flagellar motors.

Crystal structure of the FliF-FliG complex from yields insight into the assembly of the motor MS-C ring in the bacterial flagellum.

The bacterial flagellar motor is a self-assembling supramolecular nanodevice. Its spontaneous biosynthesis is initiated by the insertion of the MS ring protein FliF into the inner membrane, followed by attachment of the switch protein FliG. Assembly of this multiprotein complex is tightly regulated to avoid nonspecific aggregation, but the molecular mechanisms governing flagellar assembly are unclear.

Degradation of nuclear Ubc9 induced by listeriolysin O is dependent on K efflux.

Listeriolysin O (LLO) is a pore-forming toxin produced by L. monocytogenes, and is belonged to a protein family of cholesterol-dependent cytolysins (CDCs). Previous studies have demonstrated that LLO triggers Ubc9 degradation and disrupts host SUMOylation to facilitate bacterial infection.

A putative spermidine synthase interacts with flagellar switch protein FliM and regulates motility in Helicobacter pylori.

The flagellar motor is an important virulence factor in infection by many bacterial pathogens. Motor function can be modulated by chemotactic proteins and recently appreciated proteins that are not part of the flagellar or chemotaxis systems. How these latter proteins affect flagellar activity is not fully understood.

Structural basis of the PE-PPE protein interaction in .

(), the causative agent of tuberculosis, has developed multiple strategies to adapt to the human host. The five type VII secretion systems, ESX-1-5, direct the export of many virulence-promoting protein effectors across the complex mycobacterial cell wall. One class of ESX substrates is the PE-PPE family of proteins, which is unique to mycobacteria and essential for infection, antigenic variation, and host-pathogen interactions.

PACT Facilitates RNA-Induced Activation of MDA5 by Promoting MDA5 Oligomerization.

MDA5 is a RIG-I-like cytoplasmic sensor of dsRNA and certain RNA viruses, such as encephalomyocarditis virus, for the initiation of the IFN signaling cascade in the innate antiviral response. The affinity of MDA5 toward dsRNA is low, and its activity becomes optimal in the presence of unknown cellular coactivators. In this article, we report an essential coactivator function of dsRNA-binding protein PACT in mediating the MDA5-dependent type I IFN response.

Helicobacter pylori does not use spermidine synthase to produce spermidine.

Helicobacter pylori is the primary pathogen associated to gastritis and gastric cancer. Growth of H. pylori depends on the availability of spermidine in vivo.

Suppression of PACT-induced type I interferon production by herpes simplex virus 1 Us11 protein.

Herpes simplex virus 1 (HSV-1) Us11 protein is a double-stranded RNA-binding protein that suppresses type I interferon production through the inhibition of the cytoplasmic RNA sensor RIG-I. Whether additional cellular mediators are involved in this suppression remains to be determined. In this study, we report on the requirement of cellular double-stranded RNA-binding protein PACT for Us11-mediated perturbation of type I interferon production.

Structural basis of FliG-FliM interaction in Helicobacter pylori.

FliG and FliM are switch proteins that regulate the rotation and switching of the flagellar motor. Several assembly models for FliG and FliM have recently been proposed; however, it remains unclear whether the assembly of the switch proteins is conserved among different bacterial species. We applied a combination of pull-down, thermodynamic and structural analyses to characterize the FliM-FliG association from the mesophilic bacterium Helicobacter pylori.

Genetically encodable design of ligand "bundling" on the surface of nanoparticles.

Polyhistidine peptide dendrimer self-assembles on CdSe/ZnS quantum dots (QDs) with very high affinity and stability, a property ascribable to its multivalent geometry. Here we designed a fluorescent protein, GCN-mCherry, that exists as an oligomeric bundled structure in solution as well as on the surface to imitate the structure of a synthetic dendrimer. GCN-mCherry forms a very stable assembly with QDs, which can resist displacement by 500 mM imidazole and the dendrimer peptide, as measured by the Förster resonance energy transfer from QD to mCherry.

Influenza polymerase activity correlates with the strength of interaction between nucleoprotein and PB2 through the host-specific residue K/E627.

The ribonucleoprotein (RNP) complex is the essential transcription-replication machinery of the influenza virus. It is composed of the trimeric polymerase (PA, PB1 and PB2), nucleoprotein (NP) and RNA. Elucidating the molecular mechanisms of RNP assembly is central to our understanding of the control of viral transcription and replication and the dependence of these processes on the host cell.

Structural basis for RNA binding and homo-oligomer formation by influenza B virus nucleoprotein.

Influenza virus nucleoprotein (NP) is the major component of the viral ribonucleoprotein complex, which is crucial for the transcription and replication of the viral genome. We have determined the crystal structure of influenza B virus NP to a resolution of 3.2 Å.