Dataset Information

Exploring antibiotic resistance in environmental integron-cassettes through intI-attC amplicons deep sequencing.

ABSTRACT:

Introduction

Freshwater ecosystems provide propitious conditions for the acquisition and spread of antibiotic resistance genes (ARGs), and integrons play an important role in this process.

Material and methods

In the present study, the diversity of putative environmental integron-cassettes, as well as their potential bacterial hosts in the Velhas River (Brazil), was explored through intI-attC and 16S rRNA amplicons deep sequencing. RESULTS AND DISCUSSION: ORFs related to different biological processes were observed, from DNA integration to oxidation-reduction. ARGs-cassettes were mainly associated with class 1 mobile integrons carried by pathogenic Gammaproteobacteria, and possibly sedentary chromosomal integrons hosted by Proteobacteria and Actinobacteria. Two putative novel ARG-cassettes homologs to fosB3 and novA were detected. Regarding 16SrRNA gene analysis, taxonomic and functional profiles unveiled Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria as dominant phyla. Betaproteobacteria, Alphaproteobacteria, and Actinobacteria classes were the main contributors for KEGG orthologs associated with resistance.

Conclusions

Overall, these results provide new information about environmental integrons as a source of resistance determinants outside clinical settings and the bacterial community in the Velhas River.

SUBMITTER: Dias MF

PROVIDER: S-EPMC7966681 | biostudies-literature | 2021 Mar

REPOSITORIES: biostudies-literature

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Publications

Exploring antibiotic resistance in environmental integron-cassettes through intI-attC amplicons deep sequencing.

Dias Marcela França MF de Castro Giovanni Marques GM de Paiva Magna Cristina MC de Paula Reis Mariana M Facchin Susanne S do Carmo Anderson Oliveira AO Alves Marta Salgueiro MS Suhadolnik Maria Luíza ML de Moraes Motta Amanda A Henriques Isabel I Kalapothakis Evanguedes E Lobo Francisco Pereira FP Nascimento Andréa Maria Amaral AMA

Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology] 20201127 1

<h4>Introduction</h4>Freshwater ecosystems provide propitious conditions for the acquisition and spread of antibiotic resistance genes (ARGs), and integrons play an important role in this process.<h4>Material and methods</h4>In the present study, the diversity of putative environmental integron-cassettes, as well as their potential bacterial hosts in the Velhas River (Brazil), was explored through intI-attC and 16S rRNA amplicons deep sequencing. RESULTS AND DISCUSSION: ORFs related to different ...[more]

PMID: 33247398

Similar Datasets

Project description:Antibiotic resistance in bacteria is often due to acquisition of resistance genes associated with different mobile genetic elements. In Gram-negative bacteria, many resistance genes are found as part of small mobile genetic elements called gene cassettes, generally found integrated into larger elements called integrons. Integrons carrying antibiotic resistance gene cassettes are often associated with mobile elements and here are designated 'mobile resistance integrons' (MRIs). More than one cassette can be inserted in the same integron to create arrays that contribute to the spread of multi-resistance. In many sequences in databases such as GenBank, only the genes within cassettes, rather than whole cassettes, are annotated and the same gene/cassette may be given different names in different entries, hampering analysis. We have developed the Repository of Antibiotic resistance Cassettes (RAC) website to provide an archive of gene cassettes that includes alternative gene names from multiple nomenclature systems and allows the community to contribute new cassettes. RAC also offers an additional function that allows users to submit sequences containing cassettes or arrays for annotation using the automatic annotation system Attacca. Attacca recognizes features (gene cassettes, integron regions) and identifies cassette arrays as patterns of features and can also distinguish minor cassette variants that may encode different resistance phenotypes (aacA4 cassettes and bla cassettes-encoding β-lactamases). Gaps in annotations are manually reviewed and those found to correspond to novel cassettes are assigned unique names. While there are other websites dedicated to integrons or antibiotic resistance genes, none includes a complete list of antibiotic resistance gene cassettes in MRI or offers consistent annotation and appropriate naming of all of these cassettes in submitted sequences. RAC thus provides a unique resource for researchers, which should reduce confusion and improve the quality of annotations of gene cassettes in integrons associated with antibiotic resistance. DATABASE URL: http://www2.chi.unsw.edu.au/rac.

Project description:BACKGROUND:Integrons are genetic elements able to integrate and disseminate genes as cassettes by a site-specific recombination mechanism. These elements contain a gene coding for an integrase that carries out recombination by interacting with two different target sites; the attI site in cis with the integrase and the palindromic attC site of a gene cassette. Integron integrases (IntIs) bind specifically to the bottom strand of attC sites. The extrahelical bases resulting from folding of attC bottom strands are important for the recognition by integrases. These enzymes are directly involved in the accumulation and formation of new cassette arrangements in the variable region of integrons. Thus, it is important to better understand interactions between IntIs and their substrates. RESULTS:We compared the ability of five IntIs to carry out excision of several cassettes flanked by different attC sites. The results showed that for most cassettes, IntI1 was the most active integrase. However, IntI2*179E and SonIntIA could easily excise cassettes containing the attCdfrA1 site located upstream, whereas IntI1 and IntI3 had only a weak excision activity for these cassettes. Analysis of the secondary structure adopted by the bottom strand of attCdfrA1 has shown that the identity of the extrahelical bases and the distance between them (A-N7-8-C) differ from those of attCs contained in the cassettes most easily excisable by IntI1 (T-N6-G). We used the attCdfrA1 site upstream of the sat2 gene cassette as a template and varied the identity and spacing between the extrahelical bases in order to determine how these modifications influence the ability of IntI1, IntI2*179E, IntI3 and SonIntIA to excise cassettes. Our results show that IntI1 is more efficient in cassette excision using T-N6-G or T-N6-C attCs while IntI3 recognizes only a limited range of attCs. IntI2*179E and SonIntIA are more tolerant of changes to the identity and spacing of extrahelical bases. CONCLUSIONS:This study provides new insights into the factors that influence the efficiency of cassette excision by integron integrases. It also suggests that IntI2 and SonIntIA have an evolutionary path that is different from IntI1 and IntI3, in their ability to recognize and excise cassettes.

Dataset Information

Exploring antibiotic resistance in environmental integron-cassettes through intI-attC amplicons deep sequencing.

Introduction

Material and methods

Conclusions

Publications

Exploring antibiotic resistance in environmental integron-cassettes through intI-attC amplicons deep sequencing.

Similar Datasets

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