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1.
Mol Microbiol ; 121(6): 1245-1261, 2024 06.
Artigo em Inglês | MEDLINE | ID: mdl-38750617

RESUMO

Linear, unbranched (1,3;1,4)-ß-glucans (mixed-linkage glucans or MLGs) are commonly found in the cell walls of grasses, but have also been detected in basal land plants, algae, fungi and bacteria. Here we show that two family GT2 glycosyltransferases from the Gram-positive bacterium Sarcina ventriculi are capable of synthesizing MLGs. Immunotransmission electron microscopy demonstrates that MLG is secreted as an exopolysaccharide, where it may play a role in organizing individual cells into packets that are characteristic of Sarcina species. Heterologous expression of these two genes shows that they are capable of producing MLGs in planta, including an MLG that is chemically identical to the MLG secreted from S. ventriculi cells but which has regularly spaced (1,3)-ß-linkages in a structure not reported previously for MLGs. The tandemly arranged, paralogous pair of genes are designated SvBmlgs1 and SvBmlgs2. The data indicate that MLG synthases have evolved different enzymic mechanisms for the incorporation of (1,3)-ß- and (1,4)-ß-glucosyl residues into a single polysaccharide chain. Amino acid variants associated with the evolutionary switch from (1,4)-ß-glucan (cellulose) to MLG synthesis have been identified in the active site regions of the enzymes. The presence of MLG synthesis in bacteria could prove valuable for large-scale production of MLG for medical, food and beverage applications.


Assuntos
Glicosiltransferases , beta-Glucanas , Glicosiltransferases/metabolismo , Glicosiltransferases/genética , beta-Glucanas/metabolismo , Parede Celular/metabolismo , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Polissacarídeos Bacterianos/biossíntese , Polissacarídeos Bacterianos/metabolismo
2.
Plant Physiol ; 192(1): 119-132, 2023 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-36797772

RESUMO

The role of glycoproteins as key cell surface molecules during development and stress is well established; yet, the relationship between their structural features and functional mechanisms is poorly defined. FASCICLIN-LIKE ARABINOGALACTAN PROTEINs (FLAs), which impact plant growth and development, are an excellent example of a glycoprotein family with a complex multidomain structure. FLAs combine globular fasciclin-like (FAS1) domains with regions that are intrinsically disordered and contain glycomotifs for directing the addition of O-linked arabinogalactan (AG) glycans. Additional posttranslational modifications on FLAs include N-linked glycans in the FAS1 domains, a cleaved signal peptide at the N terminus, and often a glycosylphosphatidylinositol (GPI) anchor signal sequence at the C terminus. The roles of glycosylation, the GPI anchor, and FAS1 domain functions in the polysaccharide-rich extracellular matrix of plants remain unclear, as do the relationships between them. In this study, we examined sequence-structure-function relationships of Arabidopsis (Arabidopsis thaliana) FLA11, demonstrated to have roles in secondary cell wall (SCW) development, by introducing domain mutations and functional specialization through domain swaps with FLA3 and FLA12. We identified FAS1 domains as essential for FLA function, differentiating FLA11/FLA12, with roles in SCW development, from FLA3, specific to flowers and involved in pollen development. The GPI anchor and AG glycosylation co-regulate the cell surface location and release of FLAs into cell walls. The AG glycomotif sequence closest to the GPI anchor (AG2) is a major feature differentiating FLA11 from FLA12. The results of our study show that the multidomain structure of different FLAs influences their subcellular location and biological functions during plant development.


Assuntos
Arabidopsis , Proteínas de Plantas , Proteínas de Plantas/metabolismo , Mucoproteínas/genética , Mucoproteínas/metabolismo , Arabidopsis/metabolismo , Glicoproteínas/metabolismo , Polissacarídeos/metabolismo
3.
BMC Biol ; 21(1): 121, 2023 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-37226201

RESUMO

BACKGROUND: The ShK toxin from Stichodactyla helianthus has established the therapeutic potential of sea anemone venom peptides, but many lineage-specific toxin families in Actiniarians remain uncharacterised. One such peptide family, sea anemone 8 (SA8), is present in all five sea anemone superfamilies. We explored the genomic arrangement and evolution of the SA8 gene family in Actinia tenebrosa and Telmatactis stephensoni, characterised the expression patterns of SA8 sequences, and examined the structure and function of SA8 from the venom of T. stephensoni. RESULTS: We identified ten SA8-family genes in two clusters and six SA8-family genes in five clusters for T. stephensoni and A. tenebrosa, respectively. Nine SA8 T. stephensoni genes were found in a single cluster, and an SA8 peptide encoded by an inverted SA8 gene from this cluster was recruited to venom. We show that SA8 genes in both species are expressed in a tissue-specific manner and the inverted SA8 gene has a unique tissue distribution. While the functional activity of the SA8 putative toxin encoded by the inverted gene was inconclusive, its tissue localisation is similar to toxins used for predator deterrence. We demonstrate that, although mature SA8 putative toxins have similar cysteine spacing to ShK, SA8 peptides are distinct from ShK peptides based on structure and disulfide connectivity. CONCLUSIONS: Our results provide the first demonstration that SA8 is a unique gene family in Actiniarians, evolving through a variety of structural changes including tandem and proximal gene duplication and an inversion event that together allowed SA8 to be recruited into the venom of T. stephensoni.


Assuntos
Anêmonas-do-Mar , Animais , Anêmonas-do-Mar/genética , Genômica , Inversão Cromossômica , Cisteína , Dissulfetos
4.
Semin Cell Dev Biol ; 88: 107-118, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-29432955

RESUMO

Plant defensins are an extensive family of small cysteine rich proteins characterised by a conserved cysteine stabilised alpha beta protein fold which resembles the structure of insect and vertebrate defensins. However, secondary structure and disulphide topology indicates two independent superfamilies of defensins with similar structures that have arisen via an extreme case of convergent evolution. Defensins from plants and insects belong to the cis-defensin superfamily whereas mammalian defensins belong to the trans-defensin superfamily. Plant defensins are produced by all species of plants and although the structure is highly conserved, the amino acid sequences are highly variable with the exception of the cysteine residues that form the stabilising disulphide bonds and a few other conserved residues. The majority of plant defensins are components of the plant innate immune system but others have evolved additional functions ranging from roles in sexual reproduction and development to metal tolerance. This review focuses on the antifungal mechanisms of plant defensins. The activity of plant defensins is not limited to plant pathogens and many of the described mechanisms have been elucidated using yeast models. These mechanisms are more complex than simple membrane permeabilisation induced by many small antimicrobial peptides. Common themes that run through the characterised mechanisms are interactions with specific lipids, production of reactive oxygen species and induction of cell wall stress. Links between sequence motifs and functions are highlighted where appropriate. The complexity of the interactions between plant defensins and fungi helps explain why this protein superfamily is ubiquitous in plant innate immunity.


Assuntos
Defensinas/imunologia , Fungos/efeitos dos fármacos , Doenças das Plantas/imunologia , Imunidade Vegetal/genética , Proteínas de Plantas/imunologia , Plantas/imunologia , Parede Celular/química , Parede Celular/efeitos dos fármacos , Sequência Conservada , Defensinas/genética , Defensinas/farmacologia , Resistência à Doença/genética , Evolução Molecular , Fungos/química , Fungos/metabolismo , Regulação da Expressão Gênica de Plantas/imunologia , Interações Hospedeiro-Patógeno , Lipídeos/química , Lipídeos/imunologia , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Proteínas de Plantas/farmacologia , Plantas/genética , Plantas/microbiologia , Dobramento de Proteína , Estrutura Secundária de Proteína , Espécies Reativas de Oxigênio/imunologia , Espécies Reativas de Oxigênio/metabolismo
5.
Mol Biol Evol ; 37(8): 2155-2172, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32359163

RESUMO

Approaches for studying the evolution of globular proteins are now well established yet are unsuitable for disordered sequences. Our understanding of the evolution of proteins containing disordered regions therefore lags that of globular proteins, limiting our capacity to estimate their evolutionary history, classify paralogs, and identify potential sequence-function relationships. Here, we overcome these limitations by using new analytical approaches that project representations of sequence space to dissect the evolution of proteins with both ordered and disordered regions, and the correlated changes between these. We use the fasciclin-like arabinogalactan proteins (FLAs) as a model family, since they contain a variable number of globular fasciclin domains as well as several distinct types of disordered regions: proline (Pro)-rich arabinogalactan (AG) regions and longer Pro-depleted regions. Sequence space projections of fasciclin domains from 2019 FLAs from 78 species identified distinct clusters corresponding to different types of fasciclin domains. Clusters can be similarly identified in the seemingly random Pro-rich AG and Pro-depleted disordered regions. Sequence features of the globular and disordered regions clearly correlate with one another, implying coevolution of these distinct regions, as well as with the N-linked and O-linked glycosylation motifs. We reconstruct the overall evolutionary history of the FLAs, annotated with the changing domain architectures, glycosylation motifs, number and length of AG regions, and disordered region sequence features. Mapping these features onto the functionally characterized FLAs therefore enables their sequence-function relationships to be interrogated. These findings will inform research on the abundant disordered regions in protein families from all kingdoms of life.


Assuntos
Evolução Molecular , Proteínas Intrinsicamente Desordenadas/genética , Mucoproteínas/genética , Família Multigênica , Plantas/genética , Proteínas de Plantas/genética , Domínios Proteicos
6.
Bioinformatics ; 35(5): 743-752, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30102339

RESUMO

MOTIVATION: The cis-defensins are a superfamily of small, cationic, cysteine-rich proteins, sharing a common scaffold, but highly divergent sequences and varied functions from host-defence to signalling. Superfamily members are most abundant in plants (with some genomes containing hundreds of members), but are also found across fungi and invertebrates. However, of the thousands of cis-defensin sequences in databases, only have a handful have solved structures or assigned activities. Non-phylogenetic sequence-analysis methods are therefore necessary to use the relationships within the superfamily to classify members, and to predict and engineer functions. RESULTS: We show that the generation of a quantitative map of sequence space allows these highly divergent sequences to be usefully analyzed. This information-rich technique can identify natural groupings of sequences with similar biophysical properties, detect interpretable covarying properties, and provide information on typical or intermediate sequences for each cluster. The cis-defensin superfamily contains clearly-defined groups, identifiable based on their biophysical properties and motifs. The organization of sequences within this space also provides a foundation of understanding the ancient evolution of the superfamily. AVAILABILITY AND IMPLEMENTATION: A webtool for exploring and querying the space is hosted at TS404.shinyapps.io/DefSpace. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.


Assuntos
Sequência de Aminoácidos , Defensinas , Evolução Molecular , Genoma
7.
Proteins ; 87(7): 551-560, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30811678

RESUMO

Many of the small, cysteine-rich ion-channel modulatory peptides found in Cnidaria are distantly related to vertebrate defensins (of the trans-defensin superfamily). Transcriptomic and proteomic studies of the endemic Australian speckled sea anemone (Oulactis sp.) yielded homologous peptides to known defensin sequences. We extended these data using existing and custom-built hidden Markov models to extract defensin-like families from the transcriptomes of seven endemic Australian cnidarian species. Newly sequenced transcriptomes include three species of Actiniaria (true sea anemones); the speckled anemone (Oulactis sp.), Oulactis muscosa, Dofleinia cf. armata and a species of Corallimorpharia, Rhodactis sp. We analyzed these novel defensin-like sequences along with published homologues to study the evolution of their physico-chemical properties in vertebrate and invertebrate fauna. The cnidarian trans-defensins form a distinct cluster within the chemical space of the superfamily, with a unique set of motifs and biophysical properties. This cluster contains identifiable subgroups, whose distribution in chemical space also correlates with the divergent evolution of their structures. These sequences, currently restricted to cnidarians, form an evolutionarily distinct clade within the trans-defensin superfamily.


Assuntos
Defensinas/genética , Anêmonas-do-Mar/genética , Transcriptoma , Animais , Cisteína/química , Cisteína/genética , Defensinas/química , Evolução Molecular , Modelos Moleculares , Filogenia , Conformação Proteica , Anêmonas-do-Mar/química
9.
J Biomed Inform ; 99: 103292, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31557529

RESUMO

Created in October 2012, Wikidata is a large-scale, human-readable, machine-readable, multilingual, multidisciplinary, centralized, editable, structured, and linked knowledge-base with an increasing diversity of use cases. Here, we raise awareness of the potential use of Wikidata as a useful resource for biomedical data integration and semantic interoperability between biomedical computer systems. We show the data model and characteristics of Wikidata and explain how this database can be automatically processed by users as well as by computer methods and programs. Then, we give an overview of the medical entities and relations provided by the database and how they can be useful for various medical purposes such as clinical decision support.


Assuntos
Ontologias Biológicas , Sistemas de Gerenciamento de Base de Dados , Internet , Bases de Dados Factuais , Registros Eletrônicos de Saúde , Humanos , Multilinguismo , Semântica
10.
PLoS Comput Biol ; 13(5): e1005457, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28545146

RESUMO

Transcriptomics technologies are the techniques used to study an organism's transcriptome, the sum of all of its RNA transcripts. The information content of an organism is recorded in the DNA of its genome and expressed through transcription. Here, mRNA serves as a transient intermediary molecule in the information network, whilst noncoding RNAs perform additional diverse functions. A transcriptome captures a snapshot in time of the total transcripts present in a cell. The first attempts to study the whole transcriptome began in the early 1990s, and technological advances since the late 1990s have made transcriptomics a widespread discipline. Transcriptomics has been defined by repeated technological innovations that transform the field. There are two key contemporary techniques in the field: microarrays, which quantify a set of predetermined sequences, and RNA sequencing (RNA-Seq), which uses high-throughput sequencing to capture all sequences. Measuring the expression of an organism's genes in different tissues, conditions, or time points gives information on how genes are regulated and reveals details of an organism's biology. It can also help to infer the functions of previously unannotated genes. Transcriptomic analysis has enabled the study of how gene expression changes in different organisms and has been instrumental in the understanding of human disease. An analysis of gene expression in its entirety allows detection of broad coordinated trends which cannot be discerned by more targeted assays.


Assuntos
Perfilação da Expressão Gênica/métodos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Análise de Sequência de RNA/métodos , Animais , Análise por Conglomerados , Humanos , Processamento de Imagem Assistida por Computador , Camundongos , Análise de Sequência com Séries de Oligonucleotídeos , Especificidade de Órgãos , RNA/análise , RNA/genética , RNA/isolamento & purificação , RNA/metabolismo , Ratos
11.
Cell Mol Life Sci ; 74(4): 663-682, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27557668

RESUMO

Defensins are a well-characterised group of small, disulphide-rich, cationic peptides that are produced by essentially all eukaryotes and are highly diverse in their sequences and structures. Most display broad range antimicrobial activity at low micromolar concentrations, whereas others have other diverse roles, including cell signalling (e.g. immune cell recruitment, self/non-self-recognition), ion channel perturbation, toxic functions, and enzyme inhibition. The defensins consist of two superfamilies, each derived from an independent evolutionary origin, which have subsequently undergone extensive divergent evolution in their sequence, structure and function. Referred to as the cis- and trans-defensin superfamilies, they are classified based on their secondary structure orientation, cysteine motifs and disulphide bond connectivities, tertiary structure similarities and precursor gene sequence. The utility of displaying loops on a stable, compact, disulphide-rich core has been exploited by evolution on multiple occasions. The defensin superfamilies represent a case where the ensuing convergent evolution of sequence, structure and function has been particularly extreme. Here, we discuss the extent, causes and significance of these convergent features, drawing examples from across the eukaryotes.


Assuntos
Defensinas/genética , Defensinas/metabolismo , Filogenia , Sequência de Aminoácidos , Animais , Anti-Infecciosos/química , Anti-Infecciosos/metabolismo , Defensinas/química , Evolução Molecular , Dosagem de Genes , Humanos , Modelos Moleculares , Conformação Proteica , Alinhamento de Sequência
12.
Biochim Biophys Acta ; 1858(6): 1099-109, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26896695

RESUMO

Plant defensins interact with phospholipids in bilayers as part of their cytotoxic activity. Solanaceous class II defensins with the loop 5 sequence pattern "S-[KR]-[ILVQ]-[ILVQ]-[KR]-[KR]" interact with PI(4,5)P2. Here, the prototypical defensin of this class, NaD1, is used to characterise the biophysical interactions between these defensins and phospholipid bilayers. Binding of NaD1 to bilayers containing PI(4,5)P2 occurs rapidly and the interaction is very strong. Dual polarisation interferometry revealed that NaD1 does not dissociate from bilayers containing PI(4,5)P2. Binding of NaD1 to bilayers with or without PI(4,5)P2 induced disorder in the bilayer. However, permeabilisation assays revealed that NaD1 only permeabilised liposomes with PI(4,5)P2 in the bilayer, suggesting a role for this protein-lipid interaction in the plasma membrane permeabilising activity of this defensin. No defensins in the available databases have the PI(4,5)P2 binding sequence outside the solanaceous class II defensins, leading to the hypothesis that PI(4,5)P2 binding co-evolved with the C-terminal propeptide to protect the host cell against the effects of the tight binding of these defensins to their cognate lipid as they travel along the secretory pathway. This data has allowed us to develop a new model to explain how this class of defensins permeabilises plasma membranes to kill target cells.


Assuntos
Proteínas de Arabidopsis/fisiologia , Lipídeos de Membrana/metabolismo , NADH Desidrogenase/fisiologia , Fosfatidilinositol 4,5-Difosfato/metabolismo , Sequência de Aminoácidos , Proteínas de Arabidopsis/química , Bicamadas Lipídicas , Dados de Sequência Molecular , NADH Desidrogenase/química , Ligação Proteica , Homologia de Sequência de Aminoácidos
13.
Mol Biol Evol ; 33(9): 2345-56, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27297472

RESUMO

The defensin and defensin-like proteins are an extensive group of small, cationic, disulfide-rich proteins found in animals, plants, and fungi and mostly perform roles in host defense. The term defensin was originally used for small mammalian proteins found in neutrophils and was subsequently applied to insect proteins and plant γ-thionins based on their perceived sequence and structural similarity. Defensins are often described as ancient innate immunity molecules and classified as a single superfamily and both sequence alignments and phylogenies have been constructed. Here, we present evidence that the defensins have not all evolved from a single ancestor. Instead, they consist of two analogous superfamilies, and extensive convergent evolution is the source of their similarities. Evidence of common origin necessarily gets weaker for distantly related genes, as is the case for defensins, which are both divergent and small. We show that similarities that have been used as evidence for common origin are all expected by chance in short, constrained, disulfide-rich proteins. Differences in tertiary structure, secondary structure order, and disulfide bond connectivity indicate convergence as the likely source of the similarity. We refer to the two evolutionarily independent groups as the cis-defensins and trans-defensins based on the orientation of the most conserved pair of disulfides.


Assuntos
Defensinas/química , Defensinas/genética , Sequência de Aminoácidos , Animais , Evolução Biológica , Defensinas/metabolismo , Drosophila melanogaster , Evolução Molecular , Humanos , Modelos Moleculares , Filogenia , Estrutura Secundária de Proteína , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Relação Estrutura-Atividade
14.
BMC Bioinformatics ; 17(1): 434, 2016 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-27784265

RESUMO

BACKGROUND: Alternative sequence alignment algorithms yield different results. It is therefore useful to quantify the similarities and differences between alternative alignments of the same sequences. These measurements can identify regions of consensus that are likely to be most informative in downstream analysis. They can also highlight systematic differences between alignments that relate to differences in the alignment algorithms themselves. RESULTS: Here we present a simple method for aligning two alternative multiple sequence alignments to one another and assessing their similarity. Differences are categorised into merges, splits or shifts in one alignment relative to the other. A set of graphical visualisations allow for intuitive interpretation of the data. CONCLUSIONS: AlignStat enables the easy one-off online use of MSA similarity comparisons or into R pipelines. The web-tool is available at AlignStat.Science.LaTrobe.edu.au. The R package, readme and example data are available on CRAN and GitHub.com/TS404/AlignStat.


Assuntos
Biologia Computacional/métodos , Interpretação Estatística de Dados , Alinhamento de Sequência/métodos , Software , Algoritmos , Sequência de Aminoácidos , Humanos , Homologia de Sequência de Aminoácidos
15.
Antimicrob Agents Chemother ; 60(10): 6302-12, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27503651

RESUMO

The plant defensin NaD1 is a potent antifungal molecule that also targets tumor cells with a high efficiency. We examined the features of NaD1 that contribute to these two activities by producing a series of chimeras with NaD2, a defensin that has relatively poor activity against fungi and no activity against tumor cells. All plant defensins have a common tertiary structure known as a cysteine-stabilized α-ß motif which consists of an α helix and a triple-stranded ß-sheet stabilized by four disulfide bonds. The chimeras were produced by replacing loops 1 to 7, the sequences between each of the conserved cysteine residues on NaD1, with the corresponding loops from NaD2. The loop 5 swap replaced the sequence motif (SKILRR) that mediates tight binding with phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and is essential for the potent cytotoxic effect of NaD1 on tumor cells. Consistent with previous reports, there was a strong correlation between PI(4,5)P2 binding and the tumor cell killing activity of all of the chimeras. However, this correlation did not extend to antifungal activity. Some of the loop swap chimeras were efficient antifungal molecules, even though they bound poorly to PI(4,5)P2, suggesting that additional mechanisms operate against fungal cells. Unexpectedly, the loop 1B swap chimera was 10 times more active than NaD1 against filamentous fungi. This led to the conclusion that defensin loops have evolved as modular components that combine to make antifungal molecules with variable mechanisms of action and that artificial combinations of loops can increase antifungal activity compared to that of the natural variants.


Assuntos
Antifúngicos/farmacologia , Defensinas/química , Defensinas/farmacologia , Nicotiana/química , Antifúngicos/química , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/farmacologia , Linhagem Celular Tumoral , Membrana Celular/efeitos dos fármacos , Defensinas/genética , Defensinas/metabolismo , Avaliação Pré-Clínica de Medicamentos/métodos , Fusarium/efeitos dos fármacos , Humanos , Lipossomos , Neomicina/farmacologia , Permeabilidade , Fosfatidilinositol 4,5-Difosfato/metabolismo , Dobramento de Proteína , Proteínas Recombinantes/genética , Proteínas Recombinantes/farmacologia , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/metabolismo
16.
Chembiochem ; 16(13): 1866-1869, 2015 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-26097079

RESUMO

Mutation of the tobacco etch virus (TEV) protease nucleophile from cysteine to serine causes an approximately ∼104 -fold loss in activity. Ten rounds of directed evolution of the mutant, TEVSer , overcame the detrimental effects of nucleophile exchange to recover near-wild-type activity in the mutant TEVSer X. Rather than respecialising TEV to the new nucleophile, all the enzymes along the evolutionary trajectory also retained the ability to use the original cysteine nucleophile. Therefore the adaptive evolution of TEVSer is paralleled by a neutral trajectory for TEVCys , in which mutations that increase serine nucleophile reactivity hardly affect the reactivity of cysteine. This apparent nucleophile permissiveness explains how nucleophile switches can occur in the phylogeny of the chymotrypsin-like protease PA superfamily. Despite the changed key component of their chemical mechanisms, the evolved variants TEVSer X and TEVCys X have similar activities; this could potentially facilitate escape from adaptive conflict to enable active-site evolution.

17.
J Fungi (Basel) ; 10(1)2024 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-38248963

RESUMO

Plant defensins are a large family of small cationic proteins with diverse functions and mechanisms of action, most of which assert antifungal activity against a broad spectrum of fungi. The partial mechanism of action has been resolved for a small number of members of plant defensins, and studies have revealed that many act by more than one mechanism. The plant defensin Ppdef1 has a unique sequence and long loop 5 with fungicidal activity against a range of human fungal pathogens, but little is known about its mechanism of action. We screened the S. cerevisiae non-essential gene deletion library and identified the involvement of the mitochondria in the mechanism of action of Ppdef1. Further analysis revealed that the hyperpolarisation of the mitochondrial membrane potential (MMP) activates ROS production, vacuolar fusion and cell death and is an important step in the mechanism of action of Ppdef1, and it is likely that a similar mechanism acts in Trichophyton rubrum.

18.
J Cell Sci ; 124(Pt 12): 2058-69, 2011 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-21610089

RESUMO

Non-coding Y RNAs are required for the initiation of chromosomal DNA replication in mammalian cells. It is unknown how they perform this function or if they associate with a nuclear structure during DNA replication. Here, we investigate the association of Y RNAs with chromatin and their interaction with replication proteins during DNA replication in a human cell-free system. Our results show that fluorescently labelled Y RNAs associate with unreplicated euchromatin in late G1 phase cell nuclei before the initiation of DNA replication. Following initiation, Y RNAs are displaced locally from nascent and replicated DNA present in replication foci. In intact human cells, a substantial fraction of endogenous Y RNAs are associated with G1 phase nuclei, but not with G2 phase nuclei. Y RNAs interact and colocalise with the origin recognition complex (ORC), the pre-replication complex (pre-RC) protein Cdt1, and other proteins implicated in the initiation of DNA replication. These data support a molecular 'catch and release' mechanism for Y RNA function during the initiation of chromosomal DNA replication, which is consistent with Y RNAs acting as replication licensing factors.


Assuntos
Cromatina/metabolismo , Replicação do DNA , Eucromatina/metabolismo , Complexo de Reconhecimento de Origem/metabolismo , RNA não Traduzido/genética , RNA não Traduzido/metabolismo , Sequência de Bases , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Cromatina/genética , Eucromatina/genética , Fase G1/genética , Humanos , Microscopia Confocal , Dados de Sequência Molecular , Complexo de Reconhecimento de Origem/genética
19.
PeerJ Comput Sci ; 8: e1085, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36262159

RESUMO

Urgent global research demands real-time dissemination of precise data. Wikidata, a collaborative and openly licensed knowledge graph available in RDF format, provides an ideal forum for exchanging structured data that can be verified and consolidated using validation schemas and bot edits. In this research article, we catalog an automatable task set necessary to assess and validate the portion of Wikidata relating to the COVID-19 epidemiology. These tasks assess statistical data and are implemented in SPARQL, a query language for semantic databases. We demonstrate the efficiency of our methods for evaluating structured non-relational information on COVID-19 in Wikidata, and its applicability in collaborative ontologies and knowledge graphs more broadly. We show the advantages and limitations of our proposed approach by comparing it to the features of other methods for the validation of linked web data as revealed by previous research.

20.
Res Involv Engagem ; 8(1): 31, 2022 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-35854364

RESUMO

BACKGROUND AND OBJECTIVE: There is currently no standardised way to share information across disciplines about initiatives, including fields such as health, environment, basic science, manufacturing, media and international development. All problems, including complex global problems such as air pollution and pandemics require reliable data sharing between disciplines in order to respond effectively. Current reporting methods also lack information about the ways in which different people and organisations are involved in initiatives, making it difficult to collate and appraise data about the most effective ways to involve different people. The objective of STARDIT (Standardised Data on Initiatives) is to address current limitations and inconsistencies in sharing data about initiatives. The STARDIT system features standardised data reporting about initiatives, including who has been involved, what tasks they did, and any impacts observed. STARDIT was created to help everyone in the world find and understand information about collective human actions, which are referred to as 'initiatives'. STARDIT enables multiple categories of data to be reported in a standardised way across disciplines, facilitating appraisal of initiatives and aiding synthesis of evidence for the most effective ways for people to be involved in initiatives. This article outlines progress to date on STARDIT; current usage; information about submitting reports; planned next steps and how anyone can become involved. METHOD: STARDIT development is guided by participatory action research paradigms, and has been co-created with people from multiple disciplines and countries. Co-authors include cancer patients, people affected by rare diseases, health researchers, environmental researchers, economists, librarians and academic publishers. The co-authors also worked with Indigenous peoples from multiple countries and in partnership with an organisation working with Indigenous Australians. RESULTS AND DISCUSSION: Over 100 people from multiple disciplines and countries have been involved in co-designing STARDIT since 2019. STARDIT is the first open access web-based data-sharing system which standardises the way that information about initiatives is reported across diverse fields and disciplines, including information about which tasks were done by which stakeholders. STARDIT is designed to work with existing data standards. STARDIT data will be released into the public domain (CC0) and integrated into Wikidata; it works across multiple languages and is both human and machine readable. Reports can be updated throughout the lifetime of an initiative, from planning to evaluation, allowing anyone to be involved in reporting impacts and outcomes. STARDIT is the first system that enables sharing of standardised data about initiatives across disciplines. A working Beta version was publicly released in February 2021 (ScienceforAll.World/STARDIT). Subsequently, STARDIT reports have been created for peer-reviewed research in multiple journals and multiple research projects, demonstrating the usability. In addition, organisations including Cochrane and Australian Genomics have created prospective reports outlining planned initiatives. CONCLUSIONS: STARDIT can help create high-quality standardised information on initiatives trying to solve complex multidisciplinary global problems.


All major problems, including complex global problems such as air pollution and pandemics, require reliable data sharing between disciplines in order to respond effectively. Such problems require evidence-informed collaborative methods, multidisciplinary research and interventions in which the people who are affected are involved in every stage. However, there is currently no standardised way to share information about initiatives and problem-solving across and between fields such as health, environment, basic science, manufacturing, education, media and international development. A multi-disciplinary international team of over 100 citizens, experts and data-users has been involved in co-creating STARDIT to help everyone in the world share, find and understand information about collective human actions, which are referred to as 'initiatives'. STARDIT is an open access data-sharing system to standardise the way that information about initiatives is reported, including information about which tasks were done by different people. Reports can be updated at all stages, from planning to evaluation, and can report impacts in many languages, using Wikidata. STARDIT is free to use, and data can be submitted by anyone. Report authors can be verified to improve trust and transparency, and data checked for quality. STARDIT can help create high-quality standardised information on initiatives trying to solve complex multidisciplinary global problems. Among its main benefits, STARDIT offers those carrying out research and interventions access to standardised information which enables well-founded comparisons of the effectiveness of different methods. This article outlines progress to date; current usage; information about submitting reports; planned next steps and how anyone can become involved.

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