Gut microbiota DPP4-like enzymes are increased in type-2 diabetes and contribute to incretin inactivation.

BACKGROUND: The gut microbiota controls broad aspects of human metabolism and feeding behavior, but the basis for this control remains largely unclear. Given the key role of human dipeptidyl peptidase 4 (DPP4) in host metabolism, we investigate whether microbiota DPP4-like counterparts perform the same function. RESULTS: We identify novel functional homologs of human DPP4 in several bacterial species inhabiting the human gut, and specific associations between Parabacteroides and Porphyromonas DPP4-like genes and type 2 diabetes (T2D). We also find that the DPP4-like enzyme from the gut symbiont Parabacteroides merdae mimics the proteolytic activity of the human enzyme on peptide YY, neuropeptide Y, gastric inhibitory polypeptide (GIP), and glucagon-like peptide 1 (GLP-1) hormones in vitro. Importantly, administration of E. coli overexpressing the P. merdae DPP4-like enzyme to lipopolysaccharide-treated mice with impaired gut barrier function reduces active GIP and GLP-1 levels, which is attributed to increased DPP4 activity in the portal circulation and the cecal content. Finally, we observe that linagliptin, saxagliptin, sitagliptin, and vildagliptin, antidiabetic drugs with DPP4 inhibitory activity, differentially inhibit the activity of the DPP4-like enzyme from P. merdae. CONCLUSIONS: Our findings confirm that proteolytic enzymes produced by the gut microbiota are likely to contribute to the glucose metabolic dysfunction that underlies T2D by inactivating incretins, which might inspire the development of improved antidiabetic therapies.

The Complement Inhibitor Factor H Generates an Anti-Inflammatory and Tolerogenic State in Monocyte-Derived Dendritic Cells.

The activation of the complement system is a key initiating step in the protective innate immune-inflammatory response against injury, although it may also cause harm if left unchecked. The structurally related soluble complement inhibitors C4b-binding protein (C4BP) and factor H (FH) exert a tight regulation of the classical/lectin and alternative pathways of complement activation, respectively, attenuating the activity of the C3/C5 convertases and, consequently, avoiding serious damage to host tissues. We recently reported that the acute-phase C4BP isoform C4BP lacking the ß-chain plays a pivotal role in the modulation of the adaptive immune responses. In this study, we demonstrate that FH acts in the early stages of monocyte to dendritic cell (DC) differentiation and is able to promote a distinctive tolerogenic and anti-inflammatory profile on monocyte-derived DCs (MoDCs) challenged by a proinflammatory stimulus. Accordingly, FH-treated and LPS-matured MoDCs are characterized by altered cytoarchitecture, resembling immature MoDCs, lower expression of the maturation marker CD83 and the costimulatory molecules CD40, CD80, and CD86, decreased production of key proinflammatory Th1-cytokines (IL-12, TNF-α, IFN-γ, IL-6, and IL-8), and preferential production of immunomodulatory mediators (IL-10 and TGF-ß). Moreover, FH-treated MoDCs show low Ag uptake and, when challenged with LPS, display reduced CCR7 expression and chemotactic migration, impaired CD4(+) T cell alloproliferation, inhibition of IFN-γ secretion by the allostimulated T cells, and, conversely, induction of CD4(+)CD127(low/negative)CD25(high)Foxp3(+) regulatory T cells. Thus, this novel noncanonical role of FH as an immunological brake able to directly affect the function of MoDCs in an inflammatory environment may exhibit therapeutic potential in hypersensitivity, transplantation, and autoimmunity.

Pangenome-wide and molecular evolution analyses of the Pseudomonas aeruginosa species.

BACKGROUND: Drug treatments and vaccine designs against the opportunistic human pathogen Pseudomonas aeruginosa have multiple issues, all associated with the diverse genetic traits present in this pathogen, ranging from multi-drug resistant genes to the molecular machinery for the biosynthesis of biofilms. Several candidate vaccines against P. aeruginosa have been developed, which target the outer membrane proteins; however, major issues arise when attempting to establish complete protection against this pathogen due to its presumably genotypic variation at the strain level. To shed light on this concern, we proposed this study to assess the P. aeruginosa pangenome and its molecular evolution across multiple strains. RESULTS: The P. aeruginosa pangenome was estimated to contain more than 16,000 non-redundant genes, and approximately 15 % of these constituted the core genome. Functional analyses of the accessory genome indicated a wide presence of genetic elements directly associated with pathogenicity. An in-depth molecular evolution analysis revealed the full landscape of selection forces acting on the P. aeruginosa pangenome, in which purifying selection drives evolution in the genome of this human pathogen. We also detected distinctive positive selection in a wide variety of outer membrane proteins, with the data supporting the concept of substantial genetic variation in proteins probably recognized as antigens. Approaching the evolutionary information of genes under extremely positive selection, we designed a new Multi-Locus Sequencing Typing assay for an informative, rapid, and cost-effective genotyping of P. aeruginosa clinical isolates. CONCLUSIONS: We report the unprecedented pangenome characterization of P. aeruginosa on a large scale, which included almost 200 bacterial genomes from one single species and a molecular evolutionary analysis at the pangenome scale. Evolutionary information presented here provides a clear explanation of the issues associated with the use of protein conjugates from pili, flagella, or secretion systems as antigens for vaccine design, which exhibit high genetic variation in terms of non-synonymous substitutions in P. aeruginosa strains.

Evolutionary and sequence-based relationships in bacterial AdoMet-dependent non-coding RNA methyltransferases.

BACKGROUND: RNA post-transcriptional modification is an exciting field of research that has evidenced this editing process as a sophisticated epigenetic mechanism to fine tune the ribosome function and to control gene expression. Although tRNA modifications seem to be more relevant for the ribosome function and cell physiology as a whole, some rRNA modifications have also been seen to play pivotal roles, essentially those located in central ribosome regions. RNA methylation at nucleobases and ribose moieties of nucleotides appear to frequently modulate its chemistry and structure. RNA methyltransferases comprise a superfamily of highly specialized enzymes that accomplish a wide variety of modifications. These enzymes exhibit a poor degree of sequence similarity in spite of using a common reaction cofactor and modifying the same substrate type. RESULTS: Relationships and lineages of RNA methyltransferases have been extensively discussed, but no consensus has been reached. To shed light on this topic, we performed amino acid and codon-based sequence analyses to determine phylogenetic relationships and molecular evolution. We found that most Class I RNA MTases are evolutionarily related to protein and cofactor/vitamin biosynthesis methyltransferases. Additionally, we found that at least nine lineages explain the diversity of RNA MTases. We evidenced that RNA methyltransferases have high content of polar and positively charged amino acid, which coincides with the electrochemistry of their substrates. CONCLUSIONS: After studying almost 12,000 bacterial genomes and 2,000 patho-pangenomes, we revealed that molecular evolution of Class I methyltransferases matches the different rates of synonymous and non-synonymous substitutions along the coding region. Consequently, evolution on Class I methyltransferases selects against amino acid changes affecting the structure conformation.

Impairing methylations at ribosome RNA, a point mutation-dependent strategy for aminoglycoside resistance: the rsmG case.

INTRODUCTION: Aminoglycosides like streptomycin are well-known for binding at specific regions of ribosome RNA and then acting as translation inhibitors. Nowadays, several pathogens have been detected to acquire an undefined strategy involving mutation at non structural ribosome genes like those acting as RNA methylases. rsmG is one of those genes which encodes an AdoMet-dependent methyltransferase responsible for the synthesis of m 7 G527 in the 530 loop of bacterial 16S rRNA. This loop is universally conserved, plays a key role in ribosomal accuracy, and is a target for streptomycin binding. Loss of the m 7 G527 modification confers low-level streptomycin resistance and may affect ribosomal functioning. OBJECTIVES: After taking into account genetic information indicating that some clinical isolates of human pathogens show streptomycin resistance associated with mutations at rsmG , we decided to explore new hot spots for mutation capable of impairing the RsmG in vivo function and of promoting low-level streptomycin resistance. MATERIALS AND METHODS: To gain insights into the molecular and genetic mechanism of acquiring this aminoglycoside resistance phenotype and the emergence of high-level streptomycin resistance in rsmG mutants, we mutated Escherichia coli rsmG and also performed a genotyping study on rpsL from several isolates showing the ability to grow at higher streptomycin concentrations than parental strains. RESULTS: We found that the mutations at rpsL were preferentially present in these mutants, and we observed a clear synergy between rsmG and rpsL genes to induce streptomycin resistance. CONCLUSION: We contribute to understand a common mechanism that is probably transferable to other ribosome RNA methylase genes responsible for modifications at central sites for ribosome function.

Impairing methylations at ribosome RNA, a point mutation-dependent strategy for aminoglycoside resistance: The rsmG case / Mutaciones en genes modificadores de ARN ribosómico y la resistencia a aminoglucósidos: el caso del gen rsmG

Introduction: Aminoglycosides like streptomycin are well-known for binding at specific regions of ribosome RNA and then acting as translation inhibitors. Nowadays, several pathogens have been detected to acquire an undefined strategy involving mutation at non structural ribosome genes like those acting as RNA methylases. rsmG is one of those genes which encodes an AdoMet-dependent methyltransferase responsible for the synthesis of m 7 G527 in the 530 loop of bacterial 16S rRNA. This loop is universally conserved, plays a key role in ribosomal accuracy, and is a target for streptomycin binding. Loss of the m 7 G527 modification confers low-level streptomycin resistance and may affect ribosomal functioning. Objectives: After taking into account genetic information indicating that some clinical isolates of human pathogens show streptomycin resistance associated with mutations at rsmG , we decided to explore new hot spots for mutation capable of impairing the RsmG in vivo function and of promoting low-level streptomycin resistance. Materials and methods: To gain insights into the molecular and genetic mechanism of acquiring this aminoglycoside resistance phenotype and the emergence of high-level streptomycin resistance in rsmG mutants, we mutated Escherichia coli rsmG and also performed a genotyping study on rpsL from several isolates showing the ability to grow at higher streptomycin concentrations than parental strains. Results: We found that the mutations at rpsL were preferentially present in these mutants, and we observed a clear synergy between rsmG and rpsL genes to induce streptomycin resistance. Conclusion: We contribute to understand a common mechanism that is probably transferable to other ribosome RNA methylase genes responsible for modifications at central sites for ribosome function.

Introducción. Los aminoglucósidos son moléculas antibióticas capaces de inhibir la síntesis de proteínas bacterianas tras su unión al ribosoma procariota. La resistencia a aminoglucósidos está clásicamente asociada a mutaciones en genes estructurales del ribosoma bacteriano; sin embargo, varios estudios recientes han demostrado, de forma recurrente, la presencia de un nuevo mecanismo dependiente de mutación que no involucra genes estructurales. El gen rsmG es uno de ellos y se caracteriza por codificar una metiltransferasa que sintetiza el nucleósido m 7 G527 localizado en el loop 530 del ribosoma bacteriano, este último caracterizado como sitio preferencial al cual se une la estreptomicina. Objetivo. Partiendo de las recientes asociaciones clínicas entre las mutaciones en el gen rsmG y la resistencia a estreptomicina, este estudio se propuso la caracterización de nuevos puntos calientes de mutación en este gen que puedan causar resistencia a estreptomicina usando Escherichia coli como modelo de estudio. Materiales y métodos. Se indagó sobre el mecanismo genético y molecular por el cual se adquiere la resistencia a estreptomicina y su transición a la resistencia a altas dosis mediante mutagénesis dirigida del gen rsmG y genotipificación del gen rpsL . Resultados. Se encontró que la mutación N39A en rsmG inactiva la proteína y se reportó un nuevo conjunto de mutaciones en rpsL que confieren resistencia a altas dosis de estreptomicina. Conclusiones. Aunque los mecanismos genéticos subyacentes permanecen sin esclarecer, se concluyó que dichos patrones secuenciales de mutación podrían tener lugar en otros genes modificadores del ARN bacteriano debido a la conservación evolutiva y al papel crítico que juegan tales modificaciones en la síntesis de proteínas.

A practical guide for the computational selection of residues to be experimentally characterized in protein families.

In recent years, numerous biocomputational tools have been designed to extract functional and evolutionary information from multiple sequence alignments (MSAs) of proteins and genes. Most biologists working actively on the characterization of proteins from a single or family perspective use the MSA analysis to retrieve valuable information about amino acid conservation and the functional role of residues in query protein(s). In MSAs, adjustment of alignment parameters is a key point to improve the quality of MSA output. However, this issue is frequently underestimated and/or misunderstood by scientists and there is no in-depth knowledge available in this field. This brief review focuses on biocomputational approaches complementary to MSA to help distinguish functional residues in protein families. These additional analyses involve issues ranging from phylogenetic to statistical, which address the detection of amino acids pivotal for protein function at any level. In recent years, a large number of tools has been designed for this very purpose. Using some of these relevant, useful tools, we have designed a practical pipeline to perform in silico studies with a view to improving the characterization of family proteins and their functional residues. This review-guide aims to present biologists a set of specially designed tools to study proteins. These tools are user-friendly as they use web servers or easy-to-handle applications. Such criteria are essential for this review as most of the biologists (experimentalists) working in this field are unfamiliar with these biocomputational analysis approaches.

[Bioinformatics in Colombia: state of the art and perspectives]. / Bioinformática en Colombia: presente y futuro de la investigación biocomputacional.

Bioinformatics emerged about 50 years ago, but it was developed greatly during the early 1980s by robust databases such as GenBank, EMBL, and DNA Database of Japan (DDBJ). Bioinformatic routines were rapidly adapted once the main algorithms for sequence analysis became available worldwide. As in other science fields, bioinformatics had minimal impact in low-income countries of Latin America until the last decade. We revised the bioinformatics state of art in Colombia and found a few bioinformatics groups carrying out basic computational biology research. Nowadays, bioinformatics in Colombia has a hopeful scenario thanks to recent science policies adopted by the Colombian Government. Such policies have been adopted in order to establish a new model of sustainable scientific research. In this brief report we revise the bioinformatics state of the art in Colombia. Finally, we conclude with some considerations for the proposed science model and we describe different perspectives of interest for the Colombian scientific community.

Bioinformática en Colombia: presente y futuro de la investigación biocomputacional / Bioinformatics in Colombia: state of the art and perspectives

La bioinformática, como la conocemos hoy en día, es una de las ciencias con mayor proyección en la adquisición de conocimiento científico. Contrario a lo que se piensa, esta ciencia tuvo sus inicios en los años 50, pero no fue sino hasta hace un par de décadas cuando tuvo su verdadero auge con la creación de las primeras bases de datos y el desarrollo de algoritmos computacionales diseñados para el análisis de secuencia. El desarrollo científico y tecnológico alcanzado a nivel mundial, constantemente nos lleva a evaluar las posibilidades de transferencia de esos logros a nuestra sociedad científica. En este punto, la bioinformática se ha sumado a la larga lista de retrasos científicos de los cuales padece constantemente nuestra sociedad. No obstante, las nuevas proyecciones y políticas de investigación y desarrollo logradas recientemente en nuestro país, han abierto definitivamente el camino para la aplicación y desarrollo de la bioinformática, la cual durante años ha sido mantenida tímidamente como objeto de estudio por pocos grupos de investigación de nuestro país. Una vez fueron propuestos los actuales modelos de sostenimiento y desarrollo con base biotecnológica, se ha dado un salto generacional en la investigación computacional en Colombia y nuestros objetivos científicos, aunque a largo plazo, están trazados al mismo nivel de países como Chile, Argentina, Brasil y México, que son los referentes inmediatos para la región. En este breve ensayo queremos resaltar la situación actual en la investigación bioinformática llevada a cabo en nuestro país, así como también, plantear las perspectivas que se esperan para esta ciencia de gran impacto a nivel mundial.

Bioinformatics emerged about 50 years ago, but it was developed greatly during the early 1980’s by robust databases such as GenBank, EMBL, and DNA Database of Japan (DDBJ). Bioinformatic routines were rapidly adapted once the main algorithms for sequence analysis became available worldwide. As in other science fields, bioinformatics had minimal impact in low-income countries of Latin America until the last decade.We revised the bioinformatics state of art in Colombia and found a few bioinformatics groups carrying out basic computational biology research. Nowadays, bioinformatics in Colombia has a hopeful scenario thanks to recent science policies adopted by the Colombian Government. Such policies have been adopted in order to establish a new model of sustainable scientific research. In this brief report we revise the bioinformatics state of the art in Colombia. Finally, we conclude with some considerations for the proposed science model and we describe different perspectives of interest for the Colombian scientific community.

Dissection of functional residues in receptor activity-modifying proteins through phylogenetic and statistical analyses.

Type I and type-II functional divergences have been stated to highlight specific residues carrying out differential functions in evolutionary-divergent protein clusters from a single common ancestor. Briefly, type I analysis is based on residue constraints reflecting a gain of function just in one cluster of an entire family of proteins; while the type-II approach is based on residue constraints showing a different chemical nature in every cluster of a protein family. This last evidence is understood as differential functionality among clusters. The Receptor Activity-Modifying Proteins constitute a family characterized by its paralogous distribution in vertebrates. They are known as G-Protein Coupled Receptor modulators. Although several studies have determined their involvement in ligand binding, specificity, and enhancement of signal transduction, the responsible residues supporting those functions are unclear. Using different bioinformatic approaches, we predicted residues involved in different RAMP functional tasks. Many residues localized in an extracellular coil of RAMP proteins were predicted to be under functional divergence suggesting a gain of function in their respective proteins. Interestingly, the transmembrane region also showed important results for residues playing relevant roles where most of them showed a biased distribution on the structure. A relevant role was conferred by the enrichment of type-II residues observed in their sequences. We show a collection of residues explaining possible gain of function and differential functionality in RAMP proteins. These residues are still experimentally unexplored with regards to functionality. Finally, an evolutionary history could be discerned. Mainly, the RAMP2 cluster has evolved in a higher manner than other RAMP clusters. However, a deacceleration in the aminoacid substitution rate of RAMP2 was observed in mammals. Such effect could be caused by the co-evolution of ligands and receptors interacting with RAMP2 through evolution and/or the specialization of this cluster in GPCR modulation.