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1.
J Neuropsychol ; 18 Suppl 1: 61-72, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37139904

RESUMO

A variety of cognitive, behavioural, and emotional impairments have been reported in the literature that are associated with the resection of the temporal cortex. Klüver-Bucy syndrome is one infrequently reported disorder in the paediatric population. This paper describes the neuropsychological findings of a female paediatric patient at 7 and 10 years of age with a diagnosis of partial Klüver-Bucy syndrome (pKBS) following total resection of the amygdala and right hippocampus to resect a glioma. The patient presented emotional problems, aggressiveness, hypermetamorphosis, social indifference, and behavioural dysexecutive syndrome, which was found at both 7 and 10 years, but with a decrease in the severity of alterations in attention, impulsivity, hyperactivity, and aggressive behaviour in a second evaluation after she had a neuropsychological intervention. These findings describe the neuropsychological profile of paediatric case with resection of the amygdala and right temporal lobe.


Assuntos
Apatia , Síndrome de Kluver-Bucy , Humanos , Feminino , Criança , Síndrome de Kluver-Bucy/complicações , Lobo Temporal/cirurgia , Tonsila do Cerebelo/cirurgia , Hipocampo
2.
Front Microbiol ; 14: 1124225, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36925471

RESUMO

Shewanella spp. are Gram-negative rods widely disseminated in aquatic niches that can also be found in human-associated environments. In recent years, reports of infections caused by these bacteria have increased significantly. Mobilome and resistome analysis of a few species showed that they are versatile; however, comprehensive comparative studies in the genus are lacking. Here, we analyzed the genetic traits of 144 genomes from Shewanella spp. isolates focusing on the mobilome, resistome, and virulome to establish their evolutionary relationship and detect unique features based on their genome content and habitat. Shewanella spp. showed a great diversity of mobile genetic elements (MGEs), most of them associated with monophyletic lineages of clinical isolates. Furthermore, 79/144 genomes encoded at least one antimicrobial resistant gene with their highest occurrence in clinical-related lineages. CRISPR-Cas systems, which confer immunity against MGEs, were found in 41 genomes being I-E and I-F the more frequent ones. Virulome analysis showed that all Shewanella spp. encoded different virulence genes (motility, quorum sensing, biofilm, adherence, etc.) that may confer adaptive advantages for survival against hosts. Our data revealed that key accessory genes are frequently found in two major clinical-related groups, which encompass the opportunistic pathogens Shewanella algae and Shewanella xiamenensis together with several other species. This work highlights the evolutionary nature of Shewanella spp. genomes, capable of acquiring different key genetic traits that contribute to their adaptation to different niches and facilitate the emergence of more resistant and virulent isolates that impact directly on human and animal health.

3.
Microorganisms ; 10(6)2022 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-35744620

RESUMO

Shewanella spp. are Gram-negative bacteria that thrive in aquatic niches and also can cause infectious diseases as opportunistic pathogens. Chromosomal (CI) and mobile integrons (MI) were previously described in some Shewanella isolates. Here, we evaluated the occurrence of integrase genes, the integron systems and their genetic surroundings in the genus. We identified 22 integrase gene types, 17 of which were newly described, showing traits of multiple events of lateral genetic transfer (LGT). Phylogenetic analysis showed that most of them were strain-specific, except for Shewanella algae, where SonIntIA-like may have co-evolved within the host as typical CIs. It is noteworthy that co-existence of up to five different integrase genes within a strain, as well as their wide dissemination to Alteromonadales, Vibrionales, Chromatiales, Oceanospirillales and Enterobacterales was observed. In addition, identification of two novel MIs suggests that continuous LGT events may have occurred resembling the behavior of class 1 integrons. The constant emergence of determinants associated to antimicrobial resistance worldwide, concomitantly with novel MIs in strains capable to harbor several types of integrons, may be an alarming threat for the recruitment of novel antimicrobial resistance gene cassettes in the genus Shewanella, with its consequent contribution towards multidrug resistance in clinical isolates.

4.
ISME J ; 15(3): 636-648, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33067586

RESUMO

Bacterial viruses are widespread and abundant across natural and engineered habitats. They influence ecosystem functioning through interactions with their hosts. Laboratory studies of phage-host pairs have advanced our understanding of phenotypic and genetic diversification in bacteria and phages. However, the dynamics of phage-host interactions have been seldom recorded in complex natural environments. We conducted an observational metagenomic study of the dynamics of interaction between Gordonia and their phages using a three-year data series of samples collected from a full-scale wastewater treatment plant. The aim was to obtain a comprehensive picture of the coevolution dynamics in naturally evolving populations at relatively high time resolution. Coevolution was followed by monitoring changes over time in the CRISPR loci of Gordonia metagenome-assembled genome, and reciprocal changes in the viral genome. Genome-wide analysis indicated low strain variability of Gordonia, and almost clonal conservation of the trailer end of the CRISPR loci. Incorporation of newer spacers gave rise to multiple coexisting bacterial populations. The host population carrying a shorter CRISPR locus that contain only ancestral spacers, which has not acquired newer spacers against the coexisting phages, accounted for more than half of the total host abundance in the majority of samples. Phages genome co-evolved by introducing directional changes, with no preference for mutations within the protospacer and PAM regions. Metagenomic reconstruction of time-resolved variants of host and viral genomes revealed how the complexity at the population level has important consequences for bacteria-phage coexistence.


Assuntos
Bacteriófagos , Bactérias , Bacteriófagos/genética , Biotecnologia , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Ecossistema
5.
Curr Microbiol ; 77(12): 4029-4036, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33048176

RESUMO

In the last years, an increasing number of untreatable infections caused by drug-resistant microbes have impacted the health care system. Worldwide, infections caused by carbapenem-resistant (CR) Gram-negative bacilli have dramatically increased. Among the CR-Gram-negative bacilli, those producing carbapenemases, such as NDM-1, are the main concern. Different Enterobacterales harboring NDM-1 have been reported lately. Providencia stuartii, a member of the Morganellaceae family, is ubiquitous in the environment, but is also known to cause nosocomial infections. Here we describe the genomic analysis of two NDM-1- producing P. stuartii strains recovered from the same patient as well as other carbapenem resistant strains recovered from the same hospital. As a result of the genomic analysis thirteen resistance genes, including three to ß-lactams (blaOXA-1, blaTEM-1, blaNDM-1), four to aminoglycosides (aphA6, aac(3)-IId, aac(2')-Ia, aac(6')-Ib-cr5), one to sulfonamides (sul1), two to chloramphenicol (catB3, catA3), one to rifampicin, one to bleomycin (ble), and one to tetracycline (tet(B)) were found. Moreover, a variety of mobile genetic elements, such as insertion sequences, plasmids and phage- related sequences, were found within P. stuartii genomes. The spread of carbapenem-resistant isolates remains a significant clinical and public health concern. Therefore, we considered that the detection of CR isolates is an essential step in addressing this problem.


Assuntos
Providencia , beta-Lactamases , Antibacterianos/farmacologia , Genômica , Humanos , Testes de Sensibilidade Microbiana , Plasmídeos , Providencia/genética , beta-Lactamases/genética
6.
Front Microbiol ; 11: 342, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32256462

RESUMO

Acinetobacter baumannii is one of the most important nosocomial pathogens able to rapidly develop extensive drug resistance. Here, we study the role of accessory genome in the success of the globally disseminated clone 1 (GC1) with functional and genomic approaches. Comparative genomics was performed with available GC1 genomes (n = 106) against other A. baumannii high-risk and sporadic clones. Genetic traits related to accessory genome were found common and conserved along time as two novel regions of genome plasticity, and a CRISPR-Cas system acquired before clonal diversification located at the same loci as "sedentary" modules. Although identified within hotspot for recombination, other block of accessory genome was also "sedentary" in lineage 1 of GC1 with signs of microevolution as the AbaR0-type genomic island (GI) identified in A144 and in A155 strains which were maintained one month in independent experiments without antimicrobial pressure. The prophage YMC/09/02/B1251_ABA_BP was found to be "mobile" since, although it was shared by all GC1 genomes, it showed high intrinsic microevolution as well as mobility to different insertion sites. Interestingly, a wide variety of Insertion Sequences (IS), probably acquired by the flow of plasmids related to Rep_3 superfamily was found. These IS showed dissimilar genomic location amongst GC1 genomes presumably associated with promptly niche adaptation. On the other hand, a type VI secretion system and three efflux pumps were subjected to deep processes of genomic loss in A. baumannii but not in GC1. As a whole, these findings suggest that preservation of some genetic modules of accessory genome harbored by strains from different continents in combination with great plasticity of IS and varied flow of plasmids, may be central features of the genomic structure of GC1. Competition of A144 and A155 versus A118 (ST 404/ND) without antimicrobial pressure suggested a higher ability of GC1 to grow over a clone with sporadic behavior which explains, from an ecological perspective, the global achievement of this successful pandemic clone in the hospital habitat. Together, these data suggest an essential role of still unknown properties of "mobile" and "sedentary" accessory genome that is preserved over time under different antibiotic or stress conditions.

7.
Sci Rep ; 9(1): 8045, 2019 05 29.
Artigo em Inglês | MEDLINE | ID: mdl-31142760

RESUMO

Integrative and conjugative elements (ICEs) are mobile genetic elements that contribute to horizontal gene transfer. The aim of this work was to study different types of ICEs in clinical isolates of the emergent pathogen Shewanella spp., to compare their transfer efficiency and their ability to integrate a new host. Here we show that 3 out of 10 clinical isolates contained an ICE. Two of these elements were similar to ICEs from the SXT/R391 family and the other one was similar to ICESh95, a hybrid platform. Mating assays showed that these elements co-exist for several generations in the same host. Furthermore, transfer rates and competition assays between ICESh95 and ICESh392, an SXT-like element, suggest that the latter has evolved into a well-oiled machine that efficiently spread to different bacteria. Our results provide strong evidence of the role that ICEs play in the dissemination of genetic traits in nature and the implications that they have in the global threat of antimicrobial resistance.


Assuntos
Elementos de DNA Transponíveis/genética , Farmacorresistência Bacteriana Múltipla/genética , Transferência Genética Horizontal/genética , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Shewanella/genética , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Proteínas de Bactérias/genética , Conjugação Genética/efeitos dos fármacos , Conjugação Genética/genética , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Evolução Molecular , Transferência Genética Horizontal/efeitos dos fármacos , Variação Genética/efeitos dos fármacos , Genoma Bacteriano/genética , Infecções por Bactérias Gram-Negativas/microbiologia , Especificidade de Hospedeiro/genética , Humanos , Integrases/genética , Anotação de Sequência Molecular , Filogenia , Análise de Sequência de DNA , Shewanella/efeitos dos fármacos , Shewanella/isolamento & purificação
8.
Front Genet ; 10: 57, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30853970

RESUMO

Multidrug resistant bacteria are a serious worldwide problem, especially carbapenem-resistant Enterobacteriaceae (such as Klebsiella pneumoniae and Escherichia coli), Acinetobacter baumannii and Pseudomonas aeruginosa. Since the emergence of extensive and pan-drug resistant bacteria there are few antibiotics left to treat patients, thus novel RNA-based strategies are being considered. Here, we examine the current situation of different non-coding RNAs found in bacteria as well as their function and potential application as antimicrobial agents. Furthermore, we discuss the factors that may contribute in the efficient development of RNA-based drugs, the limitations for their implementation and the use of nanocarriers for delivery.

9.
Rev Argent Microbiol ; 51(1): 93-100, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-29945744

RESUMO

Colistin resistance can occur by chromosomal mutations and by acquisition of plasmid-carrying determinants, mainly mcr-1. In the recent years, we have observed the outburst of this resistance gene in our region. Due to the risk of the rapid dissemination of mcr-1, this finding has worried and alerted different actors from the health field and has become one of the most prolific topics. Our review compiles available reports of well-documented mcr-1-positive strains of Enterobacteriaceae, obtained from different samples in Argentina and other countries of Latin America. Furthermore, it addresses the association of mcr-1 with ESBL resistance markers and outlines the platforms involved in their dissemination.


Assuntos
Colistina/farmacologia , Farmacorresistência Bacteriana/fisiologia , Enterobacteriaceae/efeitos dos fármacos , Enterobacteriaceae/fisiologia , Plasmídeos/fisiologia , Proteínas de Bactérias/fisiologia , América Latina
10.
BMC Genomics ; 19(1): 556, 2018 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-30055586

RESUMO

BACKGROUND: Streptococcus agalactiae, also known as Group B Streptococcus (GBS), is a Gram-positive bacterium that colonizes the gastrointestinal and genitourinary tract of humans. This bacterium has also been isolated from various animals, such as fish and cattle. Non-coding RNAs (ncRNAs) can act as regulators of gene expression in bacteria, such as Streptococcus pneumoniae and Streptococcus pyogenes. However, little is known about the genomic distribution of ncRNAs and RNA families in S. agalactiae. RESULTS: Comparative genome analysis of 27 S. agalactiae strains showed more than 5 thousand genomic regions identified and classified as Core, Exclusive, and Shared genome sequences. We identified 27 to 89 RNA families per genome distributed over these regions, from these, 25 were in Core regions while Shared and Exclusive regions showed variations amongst strains. We propose that the amount and type of ncRNA present in each genome can provide a pattern to contribute in the identification of the clonal types. CONCLUSIONS: The identification of RNA families provides an insight over ncRNAs, sRNAs and ribozymes function, that can be further explored as targets for antibiotic development or studied in gene regulation of cellular processes. RNA families could be considered as markers to determine infection capabilities of different strains. Lastly, pan-genome analysis of GBS including the full range of functional transcripts provides a broader approach in the understanding of this pathogen.


Assuntos
Genoma Bacteriano , RNA não Traduzido/genética , Streptococcus agalactiae/genética , Anotação de Sequência Molecular , RNA não Traduzido/classificação
11.
J Glob Antimicrob Resist ; 11: 81-86, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28760680

RESUMO

The objective of this study was to investigate the molecular mechanisms explaining the multidrug-resistant (MDR) phenotype found in a novel clinical Shewanella sp. strain (Shew256) recovered from a diabetic patient. Whole-genome shotgun sequencing was performed using Illumina MiSeq-I and Nextera XT DNA library. De novo assembly was performed with SPAdes. RAST Server was used to predict the open-reading frames and the predictions were confirmed using BLAST. Further genomic analysis was carried out using average nucleotide identity (ANI), ACT (Artemis), OrthoMCL, ARG-ANNOT, ISfinder, PHAST, tRNAscan-SE, plasmidSPAdes, PlasmidFinder and MAUVE. PCR and plasmid extraction were also performed. Genomic analysis revealed a total of 456 predicted genes unique to Shew256 compared with other Shewanella genomes. Moreover, the presence of different resistance genes, including blaPER-2, was found. A complex class 1 integron containing the ISCR1 gene, disrupted by two putative transposase genes, was identified. Furthermore, other resistance genes, a transposon containing aph(3'), insertion sequences, phages and non-coding RNAs were also found. In conclusion, evidence of acquisition of resistance genes and mobile elements that could explain the MDR phenotype were observed. This Shewanella sp. represents a prime example of how antibiotic resistance determinants can be acquired by uncommon pathogens.


Assuntos
Elementos de DNA Transponíveis/genética , Farmacorresistência Bacteriana Múltipla/genética , Genes Bacterianos/genética , Shewanella/enzimologia , Shewanella/genética , beta-Lactamases/genética , Idoso , Antibacterianos/farmacologia , DNA Bacteriano/genética , Transferência Genética Horizontal , Genoma Bacteriano , Infecções por Bactérias Gram-Negativas/microbiologia , Humanos , Integrons , Masculino , Testes de Sensibilidade Microbiana , Fases de Leitura Aberta , Filogenia , Plasmídeos/genética , Fatores R/genética , RNA não Traduzido , Análise de Sequência de DNA , Shewanella/efeitos dos fármacos , Shewanella/isolamento & purificação , Sequenciamento Completo do Genoma
13.
PLoS One ; 11(8): e0161528, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27548264

RESUMO

Acinetobacter johnsonii rarely causes human infections. While most A. johnsonii isolates are susceptible to virtually all antibiotics, strains harboring a variety of ß-lactamases have recently been described. An A. johnsonii Aj2199 clinical strain recovered from a hospital in Buenos Aires produces PER-2 and OXA-58. We decided to delve into its genome by obtaining the whole genome sequence of the Aj2199 strain. Genome comparison studies on Aj2199 revealed 240 unique genes and a close relation to strain WJ10621, isolated from the urine of a patient in China. Genomic analysis showed evidence of horizontal genetic transfer (HGT) events. Forty-five insertion sequences and two intact prophages were found in addition to several resistance determinants such as blaPER-2, blaOXA-58, blaTEM-1, strA, strB, ereA, sul1, aacC2 and a new variant of blaOXA-211, called blaOXA-498. In particular, blaPER-2 and blaTEM-1 are present within the typical contexts previously described in the Enterobacteriaceae family. These results suggest that A. johnsonii actively acquires exogenous DNA from other bacterial species and concomitantly becomes a reservoir of resistance genes.


Assuntos
Infecções por Acinetobacter/transmissão , Acinetobacter/genética , Reservatórios de Doenças/microbiologia , Transferência Genética Horizontal , Genoma Bacteriano , beta-Lactamases/genética , Acinetobacter/classificação , Acinetobacter/efeitos dos fármacos , Acinetobacter/isolamento & purificação , Infecções por Acinetobacter/tratamento farmacológico , Infecções por Acinetobacter/microbiologia , Antibacterianos/farmacologia , Argentina , Sequência de Bases , Expressão Gênica , Sequenciamento de Nucleotídeos em Larga Escala , Hospitais , Humanos , Testes de Sensibilidade Microbiana , Família Multigênica , Mutagênese Insercional , Filogenia , Plasmídeos/química , Plasmídeos/metabolismo , Prófagos/genética , Alinhamento de Sequência , Resistência beta-Lactâmica/genética , beta-Lactamases/metabolismo
14.
Microbiology (Reading) ; 162(8): 1335-1345, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27215217

RESUMO

Shewanella spp. are currently considered to be emerging pathogens that can code for a blaOXA carbapenemase in their chromosome. Complete genome analysis of the clinical isolate Shewanella sp. Sh95 revealed that this strain is a novel species, which shares a lineage with marine isolates. Characterization of its resistome showed that it codes for genes drfA15, qacH and blaOXA-48. We propose that Shewanella sp. Sh95 acts as reservoir of blaOXA-48. Moreover, analysis of mobilome showed that it contains a novel integrative and conjugative element (ICE), named ICESh95. Comparative analysis between the close relatives ICESpuPO1 from Shewanella sp. W3-18-1 and ICE SXTMO10 from Vibrio cholerae showed that ICESh95 encompassed two new regions, a type III restriction modification system and a multidrug resistance integron. The integron platform contained a novel arrangement formed by gene cassettes drfA15 and qacH, and a class C-attC group II intron. Furthermore, insertion of ICESh95 occurred at a unique target site, which correlated with the presence of a different xis/int module. Mobility of ICESh95 was assessed and demonstrated its ability to self-transfer with high efficiency to different species of bacteria. Our results show that ICESh95 is a self-transmissible, mobile element, which can contribute to the dissemination of antimicrobial resistance; this is clearly a threat when natural bacteria from water ecosystems, such as Shewanella, act as vectors in its propagation.


Assuntos
Proteínas de Bactérias/genética , Farmacorresistência Bacteriana Múltipla/genética , Transferência Genética Horizontal/genética , Integrons/genética , Proteínas de Membrana Transportadoras/genética , Shewanella/genética , beta-Lactamases/genética , Sequência de Bases , DNA Bacteriano/genética , Genoma Bacteriano/genética , Humanos , Análise de Sequência de DNA , Shewanella/isolamento & purificação
15.
Genome Announc ; 4(3)2016 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-27151790

RESUMO

We present the draft genome of Shewanella frigidimarina Ag06-30, a marine bacterium from King George Island, Antarctica, which encodes the carbapenemase SFP-1. The assembly contains 4,799,218 bp (G+C content 41.24%). This strain harbors several mobile genetic elements that provide insight into lateral gene transfer and bacterial plasticity and evolution.

17.
Rev. Asoc. Argent. Ortop. Traumatol ; 81(4): 250-257, 2016. ilus, tab
Artigo em Espanhol | LILACS, BINACIS | ID: biblio-835449

RESUMO

Introducción: El 70-85% de la poblacion general sufre dolor lumbar. Se ha demostrado que los programas de Escuela de Columna son eficaces para el tratamiento de la lumbalgia cronica. El taping podria ser util para disminuir el dolor y normalizar la funcion muscular. El objetivo de este estudio fue evaluar la eficacia a corto y a largo plazo del taping combinado con la Escuela de Columna en el tratamiento de la lumbalgia cronica. Materiales y Métodos: Ensayo clinico controlado aleatorizado. El grupo experimental utilizo cinta (tape) y realizo Escuela de Columna, y el grupo de control solo realizo Escuela de Columna. Al comienzo y al final del tratamiento, se registraron el dolor con la escala analogica visual, la flexibilidad con el Modified Finger Tip-to-Floor Test y la funcionalidad con el Roland Morris Disability Questionnaire. Solo al inicio se midio la depresion con el Beck Depression Inventory. Resultados: Se incluyeron 220 pacientes, solo 42 del grupo experimental y 33 del grupo de control completaron el tratamiento. El delta de dolor entre la primera y la quinta sesion no mostro diferencias entre los grupos, independientemente del tiempo (p = 0,329). Tampoco hubo diferencias entre los grupos en las determinaciones de depresion, funcionalidad (p = 0,75) y flexibilidad (p = 0,20). Conclusión: El taping combinado con Escuela de Columna comparado con el tratamiento exclusivo de Escuela de Columna no resulto mas eficaz para disminuir el dolor, aumentar la funcionalidad y la flexibilidad en los pacientes con lumbalgia cronica.


Introduction: From 70% to 85% of the general population suffers from back pain. Back School programs have been effective in the treatment of chronic low back pain. Taping may be useful in reducing pain and normalizing muscle function. The objective of this study was to evaluate the short- and long-term effectiveness of combining taping with Back School. Methods: Randomized controlled clinical trial. The experimental group used tape and made Back School and the control group only made Back School. At the beginning and the end of treatment, pain was evaluated with a visual analogue scale, the flexibility was determined with the Modified Finger Tip-to-Floor Test and functionality was calculated with the Roland Morris Disability Questionnaire. Depression was recorded with the Depression Beck Inventory just at the beginning. Results: Two hundred and twenty patients were enrolled, only 42 in the experimental group and 33 in the control group completed the treatment. Pain variation between the first and the fifth session showed no differences between groups regardless of time (p = 0.329). There were no differences between groups in functionality (p = 0.75), flexibility (p = 0.20) and depression. Conclusion: The combination of taping and Back School compared with only Back School was not more effective in reducing pain, increasing functionality and flexibility in patients with chronic low back pain.


Assuntos
Humanos , Fita Atlética , Dor Lombar , Modalidades de Fisioterapia , Terapia Combinada , Bandagens , Ensaios Clínicos Controlados Aleatórios como Assunto
18.
RNA ; 21(7): 1286-93, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25956521

RESUMO

Group II introns are large ribozymes that require the assistance of intron-encoded or free-standing maturases to splice from their pre-mRNAs in vivo. They mainly splice through the classical branching pathway, being released as RNA lariats. However, group II introns can also splice through secondary pathways like hydrolysis and circularization leading to the release of linear and circular introns, respectively. Here, we assessed in vivo splicing of various constructs of the Ll.LtrB group II intron from the Gram-positive bacterium Lactococcus lactis. The study of excised intron junctions revealed, in addition to branched intron lariats, the presence of perfect end-to-end intron circles and alternatively circularized introns. Removal of the branch point A residue prevented Ll.LtrB excision through the branching pathway but did not hinder intron circle formation. Complete intron RNA circles were found associated with the intron-encoded protein LtrA forming nevertheless inactive RNPs. Traces of double-stranded head-to-tail intron DNA junctions were also detected in L. lactis RNA and nucleic acid extracts. Some intron circles and alternatively circularized introns harbored variable number of non-encoded nucleotides at their splice junction. The presence of mRNA fragments at the splice junction of some intron RNA circles provides insights into the group II intron circularization pathway in bacteria.


Assuntos
Íntrons , Lactococcus lactis/genética , DNA Bacteriano/química , DNA Bacteriano/genética , Genes Bacterianos , Imunoprecipitação , Reação em Cadeia da Polimerase , RNA Catalítico/metabolismo
20.
Nucleic Acids Res ; 42(10): 6448-62, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24748661

RESUMO

For toxin/antitoxin (TA) systems, no toxin has been identified that functions by cleaving DNA. Here, we demonstrate that RalR and RalA of the cryptic prophage rac form a type I TA pair in which the antitoxin RNA is a trans-encoded small RNA with 16 nucleotides of complementarity to the toxin mRNA. We suggest the newly discovered antitoxin gene be named ralA for RalR antitoxin. Toxin RalR functions as a non-specific endonuclease that cleaves methylated and unmethylated DNA. The RNA chaperone Hfq is required for RalA antitoxin activity and appears to stabilize RalA. Also, RalR/RalA is beneficial to the Escherichia coli host for responding to the antibiotic fosfomycin. Hence, our results indicate that cryptic prophage genes can be functionally divergent from their active phage counterparts after integration into the host genome.


Assuntos
Toxinas Bacterianas/metabolismo , Endodesoxirribonucleases/metabolismo , Proteínas de Escherichia coli/metabolismo , Escherichia coli/enzimologia , Escherichia coli/genética , Pequeno RNA não Traduzido/metabolismo , Fatores de Transcrição/metabolismo , Antibacterianos/farmacologia , Toxinas Bacterianas/biossíntese , Toxinas Bacterianas/genética , Pareamento de Bases , Farmacorresistência Bacteriana , Endodesoxirribonucleases/biossíntese , Endodesoxirribonucleases/genética , Escherichia coli/efeitos dos fármacos , Proteínas de Escherichia coli/biossíntese , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/fisiologia , Fosfomicina/farmacologia , Fator Proteico 1 do Hospedeiro/fisiologia , Biossíntese de Proteínas , RNA Mensageiro/química , Pequeno RNA não Traduzido/química , Pequeno RNA não Traduzido/genética , Fatores de Transcrição/biossíntese , Fatores de Transcrição/genética
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