DiANNA 1.1: an extension of the DiANNA web server for ternary cysteine classification

DiANNA is a recent state-of-the-art artificial neural network and web server, which determines the cysteine oxidation state and disulfide connectivity of a protein, given only its amino acid sequence. Version 1.0 of DiANNA uses a feed-forward neural network to determine which cysteines are involved in a disulfide bond, and employs a novel architecture neural network to predict which half-cystines are covalently bound to which other half-cystines. In version 1.1 of DiANNA, described here, we extend functionality by applying a support vector machine with spectrum kernel for the cysteine classification problem—to determine whether a cysteine is reduced (free in sulfhydryl state), half-cystine (involved in a disulfide bond) or bound to a metallic ligand. In the latter case, DiANNA predicts the ligand among iron, zinc, cadmium and carbon. Available at:

Purification and characterization of DR_2577 (SlpA) a major S-layer protein from Deinococcus radiodurans

The protein DR_2577 is a major Surface layer component of the radio-resistant bacterium Deinococcus radiodurans. In the present study DR_2577 has been purified and its oligomeric profile characterized by means of size exclusion chromatography and gel electrophoresis. DR_2577 was found to be organized into three hierarchical orders characterized by monomers, stable dimers formed by the occurrence of disulfide bonds, and hexamers resulting from a combination of dimers. The structural implications of these findings are discussed providing new elements for a more integrated model of this S-layer

Folding machineries displayed on a cation-exchanger for the concerted refolding of cysteine- or proline-rich proteins

<p>Abstract</p> <p>Background</p> <p><it>Escherichia coli </it>has been most widely used for the production of valuable recombinant proteins. However, over-production of heterologous proteins in <it>E. coli </it>frequently leads to their misfolding and aggregation yielding inclusion bodies. Previous attempts to refold the inclusion bodies into bioactive forms usually result in poor recovery and account for the major cost in industrial production of desired proteins from recombinant <it>E. coli</it>. Here, we describe the successful use of the immobilized folding machineries for <it>in vitro </it>refolding with the examples of high yield refolding of a ribonuclease A (RNase A) and cyclohexanone monooxygenase (CHMO).</p> <p>Results</p> <p>We have generated refolding-facilitating media immobilized with three folding machineries, mini-chaperone (a monomeric apical domain consisting of residues 191–345 of GroEL) and two foldases (DsbA and human peptidyl-prolyl <it>cis-trans </it>isomerase) by mimicking oxidative refolding chromatography. For efficient and simple purification and immobilization simultaneously, folding machineries were fused with the positively-charged consecutive 10-arginine tag at their C-terminal. The immobilized folding machineries were fully functional when assayed in a batch mode. When the refolding-facilitating matrices were applied to the refolding of denatured and reduced RNase A and CHMO, both of which contain many cysteine and proline residues, RNase A and CHMO were recovered in 73% and 53% yield of soluble protein with full enzyme activity, respectively.</p> <p>Conclusion</p> <p>The refolding-facilitating media presented here could be a cost-efficient platform and should be applicable to refold a wide range of <it>E. coli </it>inclusion bodies in high yield with biological function.</p

Functionally confirmed compound heterozygous ADAM17 missense loss-of-function variants cause neonatal inflammatory skin and bowel disease 1

A disintegrin and metalloprotease 17 (ADAM17) is the major sheddase that processes more than 80 substrates, including tumour necrosis factor-α (TNFα). The homozygous genetic deficiency of ADAM17 causing a complete loss of ADAM17 expression was reported to be linked to neonatal inflammatory skin and bowel disease 1 (NISBD1). Here we report for the first time, a family with NISBD1 caused by functionally confirmed compound heterozygous missense variants of ADAM17, namely c.1699T>C (p.Cys567Arg) and c.1799G>A (p.Cys600Tyr). Both variants were detected in two siblings with clinical features of NISBD1, such as erythroderma with exudate in whole body, recurrent skin infection and sepsis and prolonged diarrhoea. In a cell-based assay using Adam10/17 double-knockout mouse embryonic fibroblasts (Adam10/17−/− mEFs) exogenously expressing each of these mutants, phorbol 12-myristate 13-acetate-stimulated shedding was strongly reduced compared with wild-type ADAM17. Thus, in vitro functional assays demonstrated that both missense variants cause the loss-of-function of ADAM17, resulting in the development of NISBD1. Our study further expands the spectrum of genetic pathology underlying ADAM17 in NISBD1 and establishes functional assay systems for its missense variants

A simplified approach to disulfide connectivity prediction from protein sequences

<p>Abstract</p> <p>Background</p> <p>Prediction of disulfide bridges from protein sequences is useful for characterizing structural and functional properties of proteins. Several methods based on different machine learning algorithms have been applied to solve this problem and public domain prediction services exist. These methods are however still potentially subject to significant improvements both in terms of prediction accuracy and overall architectural complexity.</p> <p>Results</p> <p>We introduce new methods for predicting disulfide bridges from protein sequences. The methods take advantage of two new decomposition kernels for measuring the similarity between protein sequences according to the amino acid environments around cysteines. Disulfide connectivity is predicted in two passes. First, a binary classifier is trained to predict whether a given protein chain has at least one intra-chain disulfide bridge. Second, a multiclass classifier (plemented by 1-nearest neighbor) is trained to predict connectivity patterns. The two passes can be easily cascaded to obtain connectivity prediction from sequence alone. We report an extensive experimental comparison on several data sets that have been previously employed in the literature to assess the accuracy of cysteine bonding state and disulfide connectivity predictors.</p> <p>Conclusion</p> <p>We reach state-of-the-art results on bonding state prediction with a simple method that classifies chains rather than individual residues. The prediction accuracy reached by our connectivity prediction method compares favorably with respect to all but the most complex other approaches. On the other hand, our method does not need any model selection or hyperparameter tuning, a property that makes it less prone to overfitting and prediction accuracy overestimation.</p

PREDIÇÃO FÍSICO-QUÍMICA, MODELAGEM E ANÁLISE DO MECANISMO DE INTERAÇÃO DA QUITINASE Mo-chi1 [Moringa oleifera, LAM.], COM POLI-β-(1-4)-N-ACETIL-D-GLUCOSAMINE: UMA ABORDAGEM in silico

Chitinases are enzymes capable of hydrolyzing β-(1,4) bonds between N-acetyl-β-D-glucosamine residues (GlcNAc), present in several organisms.&nbsp;To elucidate the physicochemical properties of Mo-chi1 identified in the Moringa oleifera plant using in silico tools. After searching the Chinese Herbal Plant Genome Database, the sequence (ID: 10006495) was analyzed for signal peptide, physicochemical properties, sulfide bridges, domains, secondary structures, modeling. The mode of interaction between Mo-chi1 and chitin was predicted with the AutoDock Vina program. &nbsp;Mo-chi1 possesses signal peptide with 19 amino acids in length (cleaved: Ala19 and Ile20), forming mature polypeptide of 379 residues. The mature has Mr = 39.56 kDa, pI = 5.44, II = 35.61 and GRAVY = -0.135. It has a sulfide bridge (5Cys-Cys398). Belong to the GH18 family with E-value of 7.43e-153 (CDD) and 2.3e-90 (SMART). It has a predominance of β-sheet (16.85-37%), followed by α-Helix (23.3-30.34%) and loops (39.5-52.81%). The molecular docking study showed favorable energy for the interaction between Mo-chi1 and GlcNAc with E-value = -5.9 kcal.mol-1. &nbsp;Although Mo-chi1 showed similar physicochemical properties to other GH18 chitinases, more refined studies are needed to identify its true potential.Las quitinasas son enzimas capaces de hidrolizar enlaces β-(1,4) entre residuos de N-acetil-β-D-glucosamina (GlcNAc), presentes en varios organismos. Conocer las propiedades fisicoquímicas de Mo-chi1 identificadas en la planta de Moringa oleifera utilizando herramientas in silico. Después de buscar en la base de datos del genoma chino de plantas herbales, se analizó la secuencia (ID: 10006495) para péptido señal, propiedades fisicoquímicas, puentes de sulfuro, dominios, estructuras secundarias, modelado. El modo de interacción entre Mo-chi1 y quitina se predijo con el programa AutoDock Vina. Mo-chi1 posee péptido señal con 19 aminoácidos de longitud (escindido: Ala19 e Ile20), formando un polipéptido maduro de 379 residuos. El maduro tiene Mr = 39.56 kDa, pI = 5.44, II = 35.61 y GRAVY = -0.135. Tiene un puente de sulfuro (5Cys-Cys398). Pertenecen a la familia GH18 con un valor E de 7.43e-153 (CDD) y 2.3e-90 (SMART). Tiene un predominio de β-sheet (16.85-37%), seguido de α-Helix (23.3-30.34%) y loops (39.5-52.81%). El estudio de acoplamiento molecular mostró energía favorable para la interacción entre Mo-chi1 y GlcNAc con un valor E = -5.9 kcal.mol-1. Aunque Mo-chi1 mostró propiedades fisicoquímicas similares a otras quitinasas GH18, se necesitan estudios más refinados para identificar su verdadero potencial.Quitinases são enzimas capazes de hidrolisar ligações β-(1,4) entre os resíduos de N-acetil-β-D-glucosamina (GlcNAc), presente em diversos organismos. &nbsp;Elucidar as propriedades físico-químicas da Mo-chi1 identificada na planta Moringa oleifera empregando ferramentas in silico. &nbsp;Após busca no Chinese Herbal Plant Genome Database, a sequência (ID: 10006495) foi analisada quanto ao peptídeo sinal, propriedades físico-químicas, pontes de sulfeto, domínios, estruturas secundárias, modelagem. O modo de interação entre Mo-chi1 e quitina foi predito com o programa AutoDock Vina. &nbsp;A Mo-chi1 possui peptídeo sinal com 19 aminoácidos de comprimento (clivado: Ala19 e Ile20), formando polipeptídio maduro de 379 resíduos. A madura possui Mr = 39,56 kDa, pI = 5.44, II = 35.61 e GRAVY = -0.135. Possui uma ponte de sulfeto (5Cys-Cys398). Pertencer à família das GH18 com E-value de 7.43e-153 (CDD) e de 2.3e-90 (SMART). Detém predominância de β-folha (16,85–37%), seguidas de α-Helix (23,3–30,34%) e alças (39,5–52,81%). O estudo de docking molecular mostrou energia favorável a interação entre Mo-chi1 e GlcNAc com E-valor = &nbsp;-5.9 kcal.mol-1. Embora a Mo-chi1 tenha apresentado propriedades físico-químicas semelhantes a outras quitinases GH18, são necessários estudos mais refinados a fim de identificar seu real potencial

The logic of kinetic regulation in the thioredoxin system

<p>Abstract</p> <p>Background</p> <p>The thioredoxin system consisting of NADP(H), thioredoxin reductase and thioredoxin provides reducing equivalents to a large and diverse array of cellular processes. Despite a great deal of information on the kinetics of individual thioredoxin-dependent reactions, the kinetic regulation of this system as an integrated whole is not known. We address this by using kinetic modeling to identify and describe kinetic behavioral motifs found within the system.</p> <p>Results</p> <p>Analysis of a realistic computational model of the <it>Escherichia coli </it>thioredoxin system revealed several modes of kinetic regulation in the system. In keeping with published findings, the model showed that thioredoxin-dependent reactions were adaptable (i.e. changes to the thioredoxin system affected the kinetic profiles of these reactions). Further and in contrast to other systems-level descriptions, analysis of the model showed that apparently unrelated thioredoxin oxidation reactions can affect each other via their combined effects on the thioredoxin redox cycle. However, the scale of these effects depended on the kinetics of the individual thioredoxin oxidation reactions with some reactions more sensitive to changes in the thioredoxin cycle and others, such as the Tpx-dependent reduction of hydrogen peroxide, less sensitive to these changes. The coupling of the thioredoxin and Tpx redox cycles also allowed for ultrasensitive changes in the thioredoxin concentration in response to changes in the thioredoxin reductase concentration. We were able to describe the kinetic mechanisms underlying these behaviors precisely with analytical solutions and core models.</p> <p>Conclusions</p> <p>Using kinetic modeling we have revealed the logic that underlies the functional organization and kinetic behavior of the thioredoxin system. The thioredoxin redox cycle and associated reactions allows for a system that is adaptable, interconnected and able to display differential sensitivities to changes in this redox cycle. This work provides a theoretical, systems-biological basis for an experimental analysis of the thioredoxin system and its associated reactions.</p

A Monoallelic Variant in REST Is Associated with Non-Syndromic Autosomal Dominant Hearing Impairment in a South African Family

Hearing impairment (HI) is a sensory disorder with a prevalence of 0.0055 live births in South Africa. DNA samples from a South African family presenting with progressive, autosomal dominant non-syndromic HI were subjected to whole-exome sequencing, and a novel monoallelic variant in REST [c.1244GC; p.(C415S)], was identified as the putative causative variant. The co-segregation of the variant was confirmed with Sanger Sequencing. The variant is absent from databases, 103 healthy South African controls, and 52 South African probands with isolated HI. In silico analysis indicates that the p.C415S variant in REST substitutes a conserved cysteine and results in changes to the surrounding secondary structure and the disulphide bonds, culminating in alteration of the tertiary structure of REST. Localization studies using ectopically expressed GFP-tagged Wild type (WT) and mutant REST in HEK-293 cells show that WT REST localizes exclusively to the nucleus; however, the mutant protein localizes throughout the cell. Additionally, mutant REST has an impaired ability to repress its known target AF1q. The data demonstrates that the identified mutation compromises the function of REST and support its implication in HI. This study is the second report, worldwide, to implicate REST in HI and suggests that it should be included in diagnostic HI panels

Transport genes and chemotaxis in Laribacter hongkongensis: a genome-wide analysis

<p>Abstract</p> <p>Background</p> <p><it>Laribacter hongkongensis </it>is a Gram-negative, sea gull-shaped rod associated with community-acquired gastroenteritis. The bacterium has been found in diverse freshwater environments including fish, frogs and drinking water reservoirs. Using the complete genome sequence data of <it>L. hongkongensis</it>, we performed a comprehensive analysis of putative transport-related genes and genes related to chemotaxis, motility and quorum sensing, which may help the bacterium adapt to the changing environments and combat harmful substances.</p> <p>Results</p> <p>A genome-wide analysis using Transport Classification Database TCDB, similarity and keyword searches revealed the presence of a large diversity of transporters (n = 457) and genes related to chemotaxis (n = 52) and flagellar biosynthesis (n = 40) in the <it>L. hongkongensis </it>genome. The transporters included those from all seven major transporter categories, which may allow the uptake of essential nutrients or ions, and extrusion of metabolic end products and hazardous substances. <it>L. hongkongensis </it>is unique among closely related members of <it>Neisseriaceae </it>family in possessing higher number of proteins related to transport of ammonium, urea and dicarboxylate, which may reflect the importance of nitrogen and dicarboxylate metabolism in this assacharolytic bacterium. Structural modeling of two C^₄-dicarboxylate transporters showed that they possessed similar structures to the determined structures of other DctP-TRAP transporters, with one having an unusual disulfide bond. Diverse mechanisms for iron transport, including hemin transporters for iron acquisition from host proteins, were also identified. In addition to the chemotaxis and flagella-related genes, the <it>L. hongkongensis </it>genome also contained two copies of <it>qseB/qseC </it>homologues of the AI-3 quorum sensing system.</p> <p>Conclusions</p> <p>The large number of diverse transporters and genes involved in chemotaxis, motility and quorum sensing suggested that the bacterium may utilize a complex system to adapt to different environments. Structural modeling will provide useful insights on the transporters in <it>L. hongkongensis</it>.</p