Structural Insights into Ciona intestinalis Septins: Complexes Suggest a Mechanism for Nucleotide-dependent Interfacial Cross-talk.

Septins are filamentous nucleotide-binding proteins which can associate with membranes in a curvature-dependent manner leading to structural remodelling and barrier formation. Ciona intestinalis, a model for exploring the development and evolution of the chordate lineage, has only four septin-coding genes within its genome. These represent orthologues of the four classical mammalian subgroups, making it a minimalist non-redundant model for studying the modular assembly of septins into linear oligomers and thereby filamentous polymers.

Structural insights into the Smirnoff-Wheeler pathway for vitamin C production in the Amazon fruit camu-camu.

l-Ascorbic acid (AsA, vitamin C) is a pivotal dietary nutrient with multifaceted importance in living organisms. In plants, the Smirnoff-Wheeler pathway is the primary route for AsA biosynthesis, and understanding the mechanistic details behind its component enzymes has implications for plant biology, nutritional science, and biotechnology. As part of an initiative to determine the structures of all six core enzymes of the pathway, the present study focuses on three of them in the model species Myrciaria dubia (camu-camu): GDP-d-mannose 3',5'-epimerase (GME), l-galactose dehydrogenase (l-GalDH), and l-galactono-1,4-lactone dehydrogenase (l-GalLDH).

Engineering the catalytic activity of an Antarctic PET-degrading enzyme by loop exchange.

Several hydrolases have been described to degrade polyethylene terephthalate (PET) at moderate temperatures ranging from 25°C to 40°C. These mesophilic PET hydrolases (PETases) are less efficient in degrading this plastic polymer than their thermophilic homologs and have, therefore, been the subject of many protein engineering campaigns. However, enhancing their enzymatic activity through rational design or directed evolution poses a formidable challenge due to the need for exploring a large number of mutations.

Dissecting the Binding Interface of the Septin Polymerization Enhancer Borg BD3.

The molecular basis for septin filament assembly has begun to emerge over recent years. These filaments are essential for many septin functions which depend on their association with biological membranes or components of the cytoskeleton. Much less is known about how septins specifically interact with their binding partners.

Conservation and divergence of the G-interfaces of Drosophila melanogaster septins.

Septins possess a conserved guanine nucleotide-binding (G) domain that participates in the stabilization of organized hetero-oligomeric complexes which assemble into filaments, rings and network-like structures. The fruit fly, Drosophila melanogaster, has five such septin genes encoding Sep1, Sep2, Sep4, Sep5 and Pnut. Here, we report the crystal structure of the heterodimer formed between the G-domains of Sep1 and Sep2, the first from an insect to be described to date.

"We All Have a Job to Do in This World, It's up to Us": Farmworker and Farmer Mental Health in a Rural US-Mexico Border Region.

Improving mental health outcomes for agricultural populations is dependent on understanding the unique farming related stressors in context of the local culture and community. This study was designed to assess the prevalence of stressors and mental health risks among farmers and farmworkers in a rural, medically underserved US-Mexico border region. Of 135 study respondents, 55.

Structural Characterization of L-Galactose Dehydrogenase: An Essential Enzyme for Vitamin C Biosynthesis.

In plants, it is well-known that ascorbic acid (vitamin C) can be synthesized via multiple metabolic pathways but there is still much to be learned concerning their integration and control mechanisms. Furthermore, the structural biology of the component enzymes has been poorly exploited. Here we describe the first crystal structure for an L-galactose dehydrogenase [Spinacia oleracea GDH (SoGDH) from spinach], from the D-mannose/L-galactose (Smirnoff-Wheeler) pathway which converts L-galactose into L-galactono-1,4-lactone.

Protein structure, dynamics, and function-a 20th IUPAB Congress symposium.

A wide range of topics was raised by the four invited speakers who took part in the session on protein structure, dynamics, and function during the 20th IUPAB Congress. Most of the emphasis was placed on understanding the underlying biological phenomena of interest although applications in drug development were also mentioned. For both these purposes, it was clear that a complete description of the dynamics of the system was as important as the structures themselves.

X-ray diffraction and in vivo studies reveal the quinary structure of Trypanosoma cruzi nucleoside diphosphate kinase 1: a novel helical oligomer structure.

Trypanosoma cruzi is a flagellated protozoan parasite that causes Chagas disease, which represents a serious health problem in the Americas. Nucleoside diphosphate kinases (NDPKs) are key enzymes that are implicated in cellular energy management. TcNDPK1 is the canonical isoform in the T.

The Structural Biology of Septins and Their Filaments: An Update.

In order to fully understand any complex biochemical system from a mechanistic point of view, it is necessary to have access to the three-dimensional structures of the molecular components involved. Septins and their oligomers, filaments and higher-order complexes are no exception. Indeed, the spontaneous recruitment of different septin monomers to specific positions along a filament represents a fascinating example of subtle molecular recognition.

A special issue of dedicated to the 20th IUPAB (virtual) Congress "in" Foz do Iguaçu.

The 20th IUPAB Congress took place online, together with the annual meetings of the Brazilian Biophysical Society and the Brazilian Society for Biochemistry and Molecular Biology, from the 4th to the 8th of October, 2021. The ten keynote lectures, 24 symposia, two poster sessions, and a series of technical seminars covered the full diversity of current biophysical research and its interfaces with other fields. The event had over 1000 attendees, with an excellent gender balance.

Structural and Evolutionary Analyses of PR-4 SUGARWINs Points to a Different Pattern of Protein Function.

SUGARWINs are PR-4 proteins associated with sugarcane defense against phytopathogens. Their expression is induced in response to damage by larvae. These proteins play an important role in plant defense, in particular against fungal pathogens, such as (Went) and .

An atomic model for the human septin hexamer by cryo-EM.

In order to form functional filaments, human septins must assemble into hetero-oligomeric rod-like particles which polymerize end-to-end. The rules governing the assembly of these particles and the subsequent filaments are incompletely understood. Although crystallographic approaches have been successful in studying the separate components of the system, there has been difficulty in obtaining high resolution structures of the full particle.

Announcing the call for the Special Issue on the 20 International Congress of the International Union of Pure and Applied Biophysics (IUPAB)-virtual meeting, October 2021.

This Commentary describes a call for submissions for the upcoming Special Issue focused on the science presented at the 20 IUPAB Congress to be held in conjunction with the 45 Annual Meeting of the Brazilian Biophysical Society and the 49 Annual Meeting of the Brazilian Society for Biochemistry and Molecular Biology.

Orientational Ambiguity in Septin Coiled Coils and its Structural Basis.

Septins are an example of subtle molecular recognition whereby different paralogues must correctly assemble into functional filaments important for essential cellular events such as cytokinesis. Most possess C-terminal domains capable of forming coiled coils which are believed to be involved in filament formation and bundling. Here, we report an integrated structural approach which aims to unravel their architectural diversity and in so doing provide direct structural information for the coiled-coil regions of five human septins.

Assessing Connections in an Agricultural Community Using Social Network Analysis.

Agricultural workers experience higher rates of injury and illness than other occupational groups. NIOSH-supported agricultural centers in the U.S.

Molecular Recognition at Septin Interfaces: The Switches Hold the Key.

The assembly of a septin filament requires that homologous monomers must distinguish between one another in establishing appropriate interfaces with their neighbors. To understand this phenomenon at the molecular level, we present the first four crystal structures of heterodimeric septin complexes. We describe in detail the two distinct types of G-interface present within the octameric particles, which must polymerize to form filaments.

Molecular Structure and Functional Analysis of Pyocin S8 from Pseudomonas aeruginosa Reveals the Essential Requirement of a Glutamate Residue in the H-N-H Motif for DNase Activity.

Multidrug resistance (MDR) is a serious threat to public health, making the development of new antimicrobials an urgent necessity. Pyocins are protein antibiotics produced by strains to kill closely related cells during intraspecific competition. Here, we report an in-depth biochemical, microbicidal, and structural characterization of a new S-type pyocin, named S8.

Structures of substrate- and product-bound forms of a multi-domain copper nitrite reductase shed light on the role of domain tethering in protein complexes.

Copper-containing nitrite reductases (CuNiRs) are found in all three kingdoms of life and play a major role in the denitrification branch of the global nitro-gen cycle where nitrate is used in place of di-oxy-gen as an electron acceptor in respiratory energy metabolism. Several C- and N-terminal redox domain tethered CuNiRs have been identified and structurally characterized during the last decade. Our understanding of the role of tethered domains in these new classes of three-domain CuNiRs, where an extra cytochrome or cupredoxin domain is tethered to the catalytic two-domain CuNiRs, has remained limited.

Reverse protein engineering of a novel 4-domain copper nitrite reductase reveals functional regulation by protein-protein interaction.

Cu-containing nitrite reductases that convert NO to NO are critical enzymes in nitrogen-based energy metabolism. Among organisms in the order Rhizobiales, we have identified two copies of nirK, one encoding a new class of 4-domain CuNiR that has both cytochrome and cupredoxin domains fused at the N terminus and the other, a classical 2-domain CuNiR (Br NiR). We report the first enzymatic studies of a novel 4-domain CuNiR from Bradyrhizobium sp.

Correction: Structural characterization of a pathogenicity-related superoxide dismutase codified by a probably essential gene in Xanthomonas citri subsp. citri.

[This corrects the article DOI: 10.1371/journal.pone.

A revised order of subunits in mammalian septin complexes.

Septins are GTP binding proteins considered to be novel components of the cytoskeleton. They polymerize into filaments based on hexameric or octameric core particles in which two copies of either three or four different septins, respectively, assemble into a specific sequence. Viable combinations of the 13 human septins are believed to obey substitution rules in which the different septins involved must come from distinct subgroups.