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Integron gene cassettes harboring novel variants of D-alanine-D-alanine ligase confer high-level resistance to D-cycloserine

Rahman, MA; Kaiser, F; Jamshidi, S; Freitas Monteiro, M; Rahman, KM; Mullany, P; Roberts, AP; (2020) Integron gene cassettes harboring novel variants of D-alanine-D-alanine ligase confer high-level resistance to D-cycloserine. Scientific Reports , 10 , Article 20709. 10.1038/s41598-020-77377-4. Green open access

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Abstract

Antibiotic resistance poses an increasing threat to global health. To tackle this problem, the identification of principal reservoirs of antibiotic resistance genes (ARGs) plus an understanding of drivers for their evolutionary selection are important. During a PCR-based screen of ARGs associated with integrons in saliva-derived metagenomic DNA of healthy human volunteers, two novel variants of genes encoding a D-alanine-D-alanine ligase (ddl6 and ddl7) located within gene cassettes in the first position of a reverse integron were identified. Treponema denticola was identified as the likely host of the ddl cassettes. Both ddl6 and ddl7 conferred high level resistance to D-cycloserine when expressed in Escherichia coli with ddl7 conferring four-fold higher resistance to D-cycloserine compared to ddl6. A SNP was found to be responsible for this difference in resistance phenotype between the two ddl variants. Molecular dynamics simulations were used to explain the mechanism of this phenotypic change at the atomic scale. A hypothesis for the evolutionary selection of ddl containing integron gene cassettes is proposed, based on molecular docking of plant metabolites within the ATP and D-cycloserine binding pockets of Ddl.

Type: Article
Title: Integron gene cassettes harboring novel variants of D-alanine-D-alanine ligase confer high-level resistance to D-cycloserine
Location: England
Open access status: An open access version is available from UCL Discovery
DOI: 10.1038/s41598-020-77377-4
Publisher version: https://doi.org/10.1038/s41598-020-77377-4
Language: English
Additional information: This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Eastman Dental Institute
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Eastman Dental Institute > Microbial Diseases
URI: https://discovery.ucl.ac.uk/id/eprint/10116844
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