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Kaur J, Verma H, Kaur J, Lata P, Dhingra GG, Lal R. In Silico Analysis of the Phylogenetic and Physiological Characteristics of Sphingobium indicum B90A: A Hexachlorocyclohexane-Degrading Bacterium. Curr Microbiol 2024; 81:233. [PMID: 38904756 DOI: 10.1007/s00284-024-03762-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2024] [Accepted: 05/27/2024] [Indexed: 06/22/2024]
Abstract
The study focuses on the in silico genomic characterization of Sphingobium indicum B90A, revealing a wealth of genes involved in stress response, carbon monoxide oxidation, β-carotene biosynthesis, heavy metal resistance, and aromatic compound degradation, suggesting its potential as a bioremediation agent. Furthermore, genomic adaptations among nine Sphingomonad strains were explored, highlighting shared core genes via pangenome analysis, including those related to the shikimate pathway and heavy metal resistance. The majority of genes associated with aromatic compound degradation, heavy metal resistance, and stress response were found within genomic islands across all strains. Sphingobium indicum UT26S exhibited the highest number of genomic islands, while Sphingopyxis alaskensis RB2256 had the maximum fraction of its genome covered by genomic islands. The distribution of lin genes varied among the strains, indicating diverse genetic responses to environmental pressures. Additionally, in silico evidence of horizontal gene transfer (HGT) between plasmids pSRL3 and pISP3 of the Sphingobium and Sphingomonas genera, respectively, has been provided. The manuscript offers novel insights into strain B90A, highlighting its role in horizontal gene transfer and refining evolutionary relationships among Sphingomonad strains. The discovery of stress response genes and the czcABCD operon emphasizes the potential of Sphingomonads in consortia development, supported by genomic island analysis.
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Affiliation(s)
- Jasvinder Kaur
- Department of Zoology, Gargi College, Siri Fort Road, New Delhi, 110049, India.
| | - Helianthous Verma
- Department of Zoology, Ramjas College, University of Delhi, New Delhi, 110007, India
| | - Jaspreet Kaur
- Department of Zoology, Maitreyi College, University of Delhi, New Delhi, 110021, India
| | - Pushp Lata
- Department of Zoology, University of Delhi, New Delhi, 110007, India
| | - Gauri Garg Dhingra
- Department of Zoology, Kirori Mal College, University of Delhi, New Delhi, 110007, India
| | - Rup Lal
- Acharya Narendra Dev College, University of Delhi, New Delhi, 110019, India.
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Kardos G, Laczkó L, Kaszab E, Timmer B, Szarka K, Prépost E, Bányai K. Phylogeny of Transferable Oxazolidinone Resistance Genes and Homologs. Antibiotics (Basel) 2024; 13:311. [PMID: 38666987 PMCID: PMC11047308 DOI: 10.3390/antibiotics13040311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 03/13/2024] [Accepted: 03/22/2024] [Indexed: 04/29/2024] Open
Abstract
Oxazolidinone resistance, especially transmissible resistance, is a major public health concern, and the origin of this resistance mechanism is not yet resolved. This study aims to delve into the phylogenetic origin of the transmissible oxazolidinone resistance mechanisms conferring cross-resistance to other drugs of human and veterinary importance. The amino acid sequences of the five cfr ribosomal methylases and optrA and poxtA were used as queries in searches against 219,549 bacterial proteomes in the NCBI RefSeq database. Hits with >40% amino acid identity and >80% query coverage were aligned, and phylogenetic trees were reconstructed. All five cfr genes yielded highly similar trees, with rlmN housekeeping ribosomal methylases located basal to the sister groups of S-adenosyl-methionine-dependent methyltransferases from various Deltaproteobacteria and Actinomycetia, including antibiotic-producing Streptomyces species, and the monophyletic group of cfr genes. The basal branches of the latter contained paenibacilli and other soil bacteria; they then could be split into the clades [cfr(C):cfr(E)] and [[cfr:cfr(B)]:cfr(D)], always with different Bacillaceae in their stems. Lachnospiraceae were encountered in the basal branches of both optrA and poxtA trees. The ultimate origin of the cfr genes is the rlmN housekeeping ribosomal methylases, which evolved into a suicide-avoiding methylase in antibiotic producers; a soil organism (Lachnospiraceae, Paenibacilli) probably acted as a transfer organism into pathogenic bacteria. In the case of optrA, the porcine pathogenic Streptococcus suis was present in all branches, while the proteins closest to poxtA originated from Clostridia.
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Affiliation(s)
- Gábor Kardos
- Institute of Metagenomics, University of Debrecen, H-4032 Debrecen, Hungary; (B.T.); (K.S.)
- One Health Institute, Faculty of Health Sciences, University of Debrecen, H-4032 Debrecen, Hungary; (L.L.); (E.K.)
| | - Levente Laczkó
- One Health Institute, Faculty of Health Sciences, University of Debrecen, H-4032 Debrecen, Hungary; (L.L.); (E.K.)
- HUN-REN-DE Conservation Biology Research Group, H-4032 Debrecen, Hungary
| | - Eszter Kaszab
- One Health Institute, Faculty of Health Sciences, University of Debrecen, H-4032 Debrecen, Hungary; (L.L.); (E.K.)
- Department of Microbiology and Infectious Diseases, University of Veterinary Medicine, H-1078 Budapest, Hungary
| | - Bálint Timmer
- Institute of Metagenomics, University of Debrecen, H-4032 Debrecen, Hungary; (B.T.); (K.S.)
- Department of Medical Microbiology and Immunology, University of Pécs, H-7624 Pécs, Hungary
| | - Krisztina Szarka
- Institute of Metagenomics, University of Debrecen, H-4032 Debrecen, Hungary; (B.T.); (K.S.)
- One Health Institute, Faculty of Health Sciences, University of Debrecen, H-4032 Debrecen, Hungary; (L.L.); (E.K.)
| | - Eszter Prépost
- Department of Health Industry, University of Debrecen, H-4032 Debrecen, Hungary;
| | - Krisztián Bányai
- Pathogen Discovery Group, HUN-REN Veterinary Medical Research Institute, H-1143 Budapest, Hungary
- National Laboratory for Infectious Animal Diseases, Antimicrobial Resistance, Veterinary Public Health and Food Chain Safety, H-1143 Budapest, Hungary
- Department of Pharmacology and Toxicology, University of Veterinary Medicine, H-1078 Budapest, Hungary
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Jeremia L, Deprez BE, Dey D, Conn GL, Wuest WM. Ribosome-targeting antibiotics and resistance via ribosomal RNA methylation. RSC Med Chem 2023; 14:624-643. [PMID: 37122541 PMCID: PMC10131624 DOI: 10.1039/d2md00459c] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 02/17/2023] [Indexed: 03/05/2023] Open
Abstract
The rise of multidrug-resistant bacterial infections is a cause of global concern. There is an urgent need to both revitalize antibacterial agents that are ineffective due to resistance while concurrently developing new antibiotics with novel targets and mechanisms of action. Pathogen associated resistance-conferring ribosomal RNA (rRNA) methyltransferases are a growing threat that, as a group, collectively render a total of seven clinically-relevant ribosome-targeting antibiotic classes ineffective. Increasing frequency of identification and their growing prevalence relative to other resistance mechanisms suggests that these resistance determinants are rapidly spreading among human pathogens and could contribute significantly to the increased likelihood of a post-antibiotic era. Herein, with a view toward stimulating future studies to counter the effects of these rRNA methyltransferases, we summarize their prevalence, the fitness cost(s) to bacteria of their acquisition and expression, and current efforts toward targeting clinically relevant enzymes of this class.
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Affiliation(s)
- Learnmore Jeremia
- Department of Chemistry, Emory University 1515 Dickey Dr. Atlanta GA 30322 USA
| | - Benjamin E Deprez
- Department of Chemistry, Emory University 1515 Dickey Dr. Atlanta GA 30322 USA
| | - Debayan Dey
- Department of Biochemistry, Emory University School of Medicine 1510 Clifton Rd. Atlanta GA 30322 USA
| | - Graeme L Conn
- Department of Biochemistry, Emory University School of Medicine 1510 Clifton Rd. Atlanta GA 30322 USA
- Emory Antibiotic Resistance Center, Emory University School of Medicine 1510 Clifton Rd. Atlanta GA 30322 USA
| | - William M Wuest
- Department of Chemistry, Emory University 1515 Dickey Dr. Atlanta GA 30322 USA
- Emory Antibiotic Resistance Center, Emory University School of Medicine 1510 Clifton Rd. Atlanta GA 30322 USA
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Spreading of cfr-Carrying Plasmids among Staphylococci from Humans and Animals. Microbiol Spectr 2022; 10:e0246122. [PMID: 36413029 PMCID: PMC9769919 DOI: 10.1128/spectrum.02461-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The multidrug resistance gene cfr mediates resistance to multiple antimicrobial agents, including linezolid. Plasmids are the preferred vector for the dissemination of cfr. However, the presence and transmission of cfr-carrying plasmids among staphylococci from humans and animals have rarely been studied. Here, we investigated the presence of the cfr gene in 2,250 staphylococci of human clinical origin collected in Zhejiang, China, in 1998 to 2021 and in 3,329 porcine staphylococci preserved in our laboratories. The cfr gene was detected in 38 human isolates; its presence in Staphylococcus haemolyticus and Staphylococcus cohnii in 2003 was earlier than that identified in 2005, and Staphylococcus capitis (n = 30) was the predominant species. The cfr-carrying fragment in 38 isolates exhibited >99% nucleotide sequence similarity to plasmid pLRSA417 (39,504 bp), which was identified in 2015 and originated from a human clinical methicillin-resistant Staphylococcus aureus isolate from Zhejiang, China. The cfr-carrying plasmids in 18 MinION-sequenced staphylococci ranged in size from 32,697 bp to 43,457 bp. Fifteen plasmids were identical to pLRSA417, except for the inversion of an 8.4-kb segment comprising IS256-aacA/aphD-ISEnfa4_1-cfr-ISEnfa4_2, while the remaining 3 plasmids exhibited slightly different structures. Among the 114 cfr-positive staphylococci from pigs, pLRSA417-like plasmids were detected in 3 isolates. Intraspecies and interspecies conjugation occurred in human-derived pLRSA417-like plasmids. The presence of pLRSA417-like plasmids in staphylococci from multiple geographic regions and different hosts implied the possible transmission of the respective isolates between humans and animals. IMPORTANCE The therapeutic efficacy of the oxazolidinone antimicrobial linezolid is reduced by the emergence and dissemination of the multidrug resistance gene cfr. The cfr-carrying plasmid pLRSA417 was first identified in a clinical methicillin-resistant Staphylococcus aureus isolate, but its presence in staphylococci of human and animal origin has not been reported previously. This study showed that conjugative plasmids similar to pLRSA417 were detected mainly in Staphylococcus capitis and existed in different staphylococci in 2003 to 2021 in various clinical departments in the same hospital. pLRSA417-like plasmids were also present in staphylococci of food animal sources from different geographic regions, which suggested possible transmission among humans and animals.
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Nguyen TQ, Nicolet Y. Structure and Catalytic Mechanism of Radical SAM Methylases. Life (Basel) 2022; 12:1732. [PMID: 36362886 PMCID: PMC9692996 DOI: 10.3390/life12111732] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/25/2022] [Accepted: 10/26/2022] [Indexed: 08/14/2023] Open
Abstract
Methyl transfer is essential in myriad biological pathways found across all domains of life. Unlike conventional methyltransferases that catalyze this reaction through nucleophilic substitution, many members of the radical S-adenosyl-L-methionine (SAM) enzyme superfamily use radical-based chemistry to methylate unreactive carbon centers. These radical SAM methylases reductively cleave SAM to generate a highly reactive 5'-deoxyadenosyl radical, which initiates a broad range of transformations. Recently, crystal structures of several radical SAM methylases have been determined, shedding light on the unprecedented catalytic mechanisms used by these enzymes to overcome the substantial activation energy barrier of weakly nucleophilic substrates. Here, we review some of the discoveries on this topic over the last decade, focusing on enzymes for which three-dimensional structures are available to identify the key players in the mechanisms, highlighting the dual function of SAM as a methyl donor and a 5'-deoxyadenosyl radical or deprotonating base source. We also describe the role of the protein matrix in orchestrating the reaction through different strategies to catalyze such challenging methylations.
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Affiliation(s)
| | - Yvain Nicolet
- Metalloproteins Unit, Univ. Grenoble Alpes, CEA, CNRS, IBS, F-38000 Grenoble, France
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Yu S, Zhang Z, Li J, Zhu Y, Yin Y, Zhang X, Dai Y, Zhang A, Li C, Zhu Y, Fan J, Ruan Y, Dong X. Genome-wide identification and characterization of lncRNAs in sunflower endosperm. BMC PLANT BIOLOGY 2022; 22:494. [PMID: 36271333 PMCID: PMC9587605 DOI: 10.1186/s12870-022-03882-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Accepted: 10/13/2022] [Indexed: 06/01/2023]
Abstract
BACKGROUND Long non-coding RNAs (lncRNAs), as important regulators, play important roles in plant growth and development. The expression and epigenetic regulation of lncRNAs remain uncharacterized generally in plant seeds, especially in the transient endosperm of the dicotyledons. RESULTS In this study, we identified 11,840 candidate lncRNAs in 12 day-after-pollination sunflower endosperm by analyzing RNA-seq data. These lncRNAs were evenly distributed in all chromosomes and had specific features that were distinct from mRNAs including tissue-specificity expression, shorter and fewer exons. By GO analysis of protein coding genes showing strong correlation with the lncRNAs, we revealed that these lncRNAs potential function in many biological processes of seed development. Additionally, genome-wide DNA methylation analyses revealed that the level of DNA methylation at the transcription start sites was negatively correlated with gene expression levels in lncRNAs. Finally, 36 imprinted lncRNAs were identified including 32 maternally expressed lncRNAs and four paternally expressed lncRNAs. In CG and CHG context, DNA methylation levels of imprinted lncRNAs in the upstream and gene body regions were slightly lower in the endosperm than that in embryo tissues, which indicated that the maternal demethylation potentially induce the paternally bias expression of imprinted lncRNAs in sunflower endosperm. CONCLUSION Our findings not only identified and characterized lncRNAs on a genome-wide scale in the development of sunflower endosperm, but also provide novel insights into the parental effects and epigenetic regulation of lncRNAs in dicotyledonous seeds.
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Affiliation(s)
- Shuai Yu
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866, Liaoning, China
- Shenyang City Key Laboratory of Maize Genomic Selection Breeding, Shenyang, 110866, Liaoning, China
| | - Zhichao Zhang
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866, Liaoning, China
- Shenyang City Key Laboratory of Maize Genomic Selection Breeding, Shenyang, 110866, Liaoning, China
| | - Jing Li
- School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang, China
| | - Yanbin Zhu
- State Key Laboratory of Maize Bio-Breeding, Shenyang, China
- State Key Laboratory of the Northeast Crop Genetics and Breeding, Shenyang, China
| | - Yanzhe Yin
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866, Liaoning, China
- Shenyang City Key Laboratory of Maize Genomic Selection Breeding, Shenyang, 110866, Liaoning, China
| | - Xiaoyu Zhang
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866, Liaoning, China
- Shenyang City Key Laboratory of Maize Genomic Selection Breeding, Shenyang, 110866, Liaoning, China
| | - Yuxin Dai
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866, Liaoning, China
- Shenyang City Key Laboratory of Maize Genomic Selection Breeding, Shenyang, 110866, Liaoning, China
| | - Ao Zhang
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866, Liaoning, China
- Shenyang City Key Laboratory of Maize Genomic Selection Breeding, Shenyang, 110866, Liaoning, China
| | - Cong Li
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866, Liaoning, China
- Shenyang City Key Laboratory of Maize Genomic Selection Breeding, Shenyang, 110866, Liaoning, China
| | - Yanshu Zhu
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866, Liaoning, China
- Shenyang City Key Laboratory of Maize Genomic Selection Breeding, Shenyang, 110866, Liaoning, China
| | - Jinjuan Fan
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866, Liaoning, China
- Shenyang City Key Laboratory of Maize Genomic Selection Breeding, Shenyang, 110866, Liaoning, China
| | - Yanye Ruan
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866, Liaoning, China
- Shenyang City Key Laboratory of Maize Genomic Selection Breeding, Shenyang, 110866, Liaoning, China
| | - Xiaomei Dong
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866, Liaoning, China.
- Shenyang City Key Laboratory of Maize Genomic Selection Breeding, Shenyang, 110866, Liaoning, China.
- State Key Laboratory of Maize Bio-Breeding, Shenyang, China.
- State Key Laboratory of the Northeast Crop Genetics and Breeding, Shenyang, China.
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Kang J, Liu Y, Chen X, Xu F, Wang H, Xiong W, Li X. Metagenomic insights into the antibiotic resistomes of typical Chinese dairy farm environments. Front Microbiol 2022; 13:990272. [PMID: 36246251 PMCID: PMC9555277 DOI: 10.3389/fmicb.2022.990272] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Accepted: 08/24/2022] [Indexed: 11/13/2022] Open
Abstract
Antibiotic resistance genes (ARGs) in the environment pose a threat to human and animal health. Dairy cows are important livestock in China; however, a comprehensive understanding of antibiotic resistance in their production environment has not been well clarified. In this study, we used metagenomic methods to analyze the resistomes, microbiomes, and potential ARG bacterial hosts in typical dairy farm environments (including feces, wastewater, and soil). The ARGs resistant to tetracyclines, MLS, β-lactams, aminoglycoside, and multidrug was dominant in the dairy farm ecosystem. The abundance and diversity of total ARGs in dairy feces and wastewater were significantly higher than in soil (P < 0.05). The same environmental samples from different dairy have similar resistomes and microbiomes. A high detection rate of tet(X) in wastewater and feces (100% and 71.4%, respectively), high abundance (range from 5.74 to 68.99 copies/Gb), and the finding of tet(X5) challenged the clinical application of the last antibiotics resort of tigecycline. Network analysis identified Bacteroides as the dominant genus in feces and wastewater, which harbored the greatest abundance of their respective total ARG coverage and shared ARGs. These results improved our understanding of ARG profiles and their bacterial hosts in dairy farm environments and provided a basis for further surveillance.
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Affiliation(s)
- Jijun Kang
- Key Laboratory of Animal Antimicrobial Resistance Surveillance, Ministry of Agriculture and Rural Affairs, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
- Laboratory of Quality and Safety Risk Assessment for Products on Feed-origin Risk Factor, Ministry of Agriculture and Rural Affairs, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yiming Liu
- Key Laboratory of Animal Antimicrobial Resistance Surveillance, Ministry of Agriculture and Rural Affairs, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
- Laboratory of Quality and Safety Risk Assessment for Products on Feed-origin Risk Factor, Ministry of Agriculture and Rural Affairs, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xiaojie Chen
- Key Laboratory of Animal Antimicrobial Resistance Surveillance, Ministry of Agriculture and Rural Affairs, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
- Laboratory of Quality and Safety Risk Assessment for Products on Feed-origin Risk Factor, Ministry of Agriculture and Rural Affairs, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Fei Xu
- Key Laboratory of Animal Antimicrobial Resistance Surveillance, Ministry of Agriculture and Rural Affairs, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
- Laboratory of Quality and Safety Risk Assessment for Products on Feed-origin Risk Factor, Ministry of Agriculture and Rural Affairs, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Honglei Wang
- Key Laboratory of Animal Antimicrobial Resistance Surveillance, Ministry of Agriculture and Rural Affairs, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
- Laboratory of Quality and Safety Risk Assessment for Products on Feed-origin Risk Factor, Ministry of Agriculture and Rural Affairs, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Wenguang Xiong
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutic Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
- *Correspondence: Wenguang Xiong,
| | - Xiubo Li
- Key Laboratory of Animal Antimicrobial Resistance Surveillance, Ministry of Agriculture and Rural Affairs, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
- Laboratory of Quality and Safety Risk Assessment for Products on Feed-origin Risk Factor, Ministry of Agriculture and Rural Affairs, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
- Xiubo Li,
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Fischer TR, Meidner L, Schwickert M, Weber M, Zimmermann RA, Kersten C, Schirmeister T, Helm M. Chemical biology and medicinal chemistry of RNA methyltransferases. Nucleic Acids Res 2022; 50:4216-4245. [PMID: 35412633 PMCID: PMC9071492 DOI: 10.1093/nar/gkac224] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 03/17/2022] [Accepted: 04/08/2022] [Indexed: 12/24/2022] Open
Abstract
RNA methyltransferases (MTases) are ubiquitous enzymes whose hitherto low profile in medicinal chemistry, contrasts with the surging interest in RNA methylation, the arguably most important aspect of the new field of epitranscriptomics. As MTases become validated as drug targets in all major fields of biomedicine, the development of small molecule compounds as tools and inhibitors is picking up considerable momentum, in academia as well as in biotech. Here we discuss the development of small molecules for two related aspects of chemical biology. Firstly, derivates of the ubiquitous cofactor S-adenosyl-l-methionine (SAM) are being developed as bioconjugation tools for targeted transfer of functional groups and labels to increasingly visible targets. Secondly, SAM-derived compounds are being investigated for their ability to act as inhibitors of RNA MTases. Drug development is moving from derivatives of cosubstrates towards higher generation compounds that may address allosteric sites in addition to the catalytic centre. Progress in assay development and screening techniques from medicinal chemistry have led to recent breakthroughs, e.g. in addressing human enzymes targeted for their role in cancer. Spurred by the current pandemic, new inhibitors against coronaviral MTases have emerged at a spectacular rate, including a repurposed drug which is now in clinical trial.
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Affiliation(s)
- Tim R Fischer
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, 55128Mainz, Germany
| | - Laurenz Meidner
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, 55128Mainz, Germany
| | - Marvin Schwickert
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, 55128Mainz, Germany
| | - Marlies Weber
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, 55128Mainz, Germany
| | - Robert A Zimmermann
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, 55128Mainz, Germany
| | - Christian Kersten
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, 55128Mainz, Germany
| | - Tanja Schirmeister
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, 55128Mainz, Germany
| | - Mark Helm
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, 55128Mainz, Germany
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9
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Algarni S, Ricke SC, Foley SL, Han J. The Dynamics of the Antimicrobial Resistance Mobilome of Salmonella enterica and Related Enteric Bacteria. Front Microbiol 2022; 13:859854. [PMID: 35432284 PMCID: PMC9008345 DOI: 10.3389/fmicb.2022.859854] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 03/07/2022] [Indexed: 12/31/2022] Open
Abstract
The foodborne pathogen Salmonella enterica is considered a global public health risk. Salmonella enterica isolates can develop resistance to several antimicrobial drugs due to the rapid spread of antimicrobial resistance (AMR) genes, thus increasing the impact on hospitalization and treatment costs, as well as the healthcare system. Mobile genetic elements (MGEs) play key roles in the dissemination of AMR genes in S. enterica isolates. Multiple phenotypic and molecular techniques have been utilized to better understand the biology and epidemiology of plasmids including DNA sequence analyses, whole genome sequencing (WGS), incompatibility typing, and conjugation studies of plasmids from S. enterica and related species. Focusing on the dynamics of AMR genes is critical for identification and verification of emerging multidrug resistance. The aim of this review is to highlight the updated knowledge of AMR genes in the mobilome of Salmonella and related enteric bacteria. The mobilome is a term defined as all MGEs, including plasmids, transposons, insertion sequences (ISs), gene cassettes, integrons, and resistance islands, that contribute to the potential spread of genes in an organism, including S. enterica isolates and related species, which are the focus of this review.
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Affiliation(s)
- Suad Algarni
- Division of Microbiology, FDA National Center for Toxicological Research, Jefferson, AR, United States
- Cellular and Molecular Biology Graduate Program, University of Arkansas, Fayetteville, AR, United States
| | - Steven C. Ricke
- Meat Science and Animal Biologics Discovery Program, Department of Animal and Dairy Sciences, University of Wisconsin, Madison, WI, United States
| | - Steven L. Foley
- Division of Microbiology, FDA National Center for Toxicological Research, Jefferson, AR, United States
- Cellular and Molecular Biology Graduate Program, University of Arkansas, Fayetteville, AR, United States
| | - Jing Han
- Division of Microbiology, FDA National Center for Toxicological Research, Jefferson, AR, United States
- *Correspondence: Jing Han,
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10
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Tsai K, Stojković V, Noda-Garcia L, Young ID, Myasnikov AG, Kleinman J, Palla A, Floor SN, Frost A, Fraser JS, Tawfik DS, Fujimori DG. Directed evolution of the rRNA methylating enzyme Cfr reveals molecular basis of antibiotic resistance. eLife 2022; 11:e70017. [PMID: 35015630 PMCID: PMC8752094 DOI: 10.7554/elife.70017] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 11/25/2021] [Indexed: 12/11/2022] Open
Abstract
Alteration of antibiotic binding sites through modification of ribosomal RNA (rRNA) is a common form of resistance to ribosome-targeting antibiotics. The rRNA-modifying enzyme Cfr methylates an adenosine nucleotide within the peptidyl transferase center, resulting in the C-8 methylation of A2503 (m8A2503). Acquisition of cfr results in resistance to eight classes of ribosome-targeting antibiotics. Despite the prevalence of this resistance mechanism, it is poorly understood whether and how bacteria modulate Cfr methylation to adapt to antibiotic pressure. Moreover, direct evidence for how m8A2503 alters antibiotic binding sites within the ribosome is lacking. In this study, we performed directed evolution of Cfr under antibiotic selection to generate Cfr variants that confer increased resistance by enhancing methylation of A2503 in cells. Increased rRNA methylation is achieved by improved expression and stability of Cfr through transcriptional and post-transcriptional mechanisms, which may be exploited by pathogens under antibiotic stress as suggested by natural isolates. Using a variant that achieves near-stoichiometric methylation of rRNA, we determined a 2.2 Å cryo-electron microscopy structure of the Cfr-modified ribosome. Our structure reveals the molecular basis for broad resistance to antibiotics and will inform the design of new antibiotics that overcome resistance mediated by Cfr.
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Affiliation(s)
- Kaitlyn Tsai
- Department of Cellular and Molecular Pharmacology, University of California San FranciscoSan FranciscoUnited States
| | - Vanja Stojković
- Department of Cellular and Molecular Pharmacology, University of California San FranciscoSan FranciscoUnited States
| | - Lianet Noda-Garcia
- Department of Biomolecular Sciences, Weizmann Institute of ScienceRehovotIsrael
| | - Iris D Young
- Department of Bioengineering and Therapeutic Sciences, University of California San FranciscoSan FranciscoUnited States
| | - Alexander G Myasnikov
- Department of Biochemistry and Biophysics, University of California San FranciscoSan FranciscoUnited States
| | - Jordan Kleinman
- Department of Cellular and Molecular Pharmacology, University of California San FranciscoSan FranciscoUnited States
| | - Ali Palla
- Department of Cellular and Molecular Pharmacology, University of California San FranciscoSan FranciscoUnited States
| | - Stephen N Floor
- Helen Diller Family Comprehensive Cancer Center, University of California San FranciscoSan FranciscoUnited States
- Department of Cell and Tissue Biology, University of California San FranciscoSan FranciscoUnited States
| | - Adam Frost
- Department of Biochemistry and Biophysics, University of California San FranciscoSan FranciscoUnited States
- Quantitative Biosciences Institute, University of California San FranciscoSan FranciscoUnited States
| | - James S Fraser
- Department of Bioengineering and Therapeutic Sciences, University of California San FranciscoSan FranciscoUnited States
- Quantitative Biosciences Institute, University of California San FranciscoSan FranciscoUnited States
| | - Dan S Tawfik
- Department of Biomolecular Sciences, Weizmann Institute of ScienceRehovotIsrael
| | - Danica Galonić Fujimori
- Department of Cellular and Molecular Pharmacology, University of California San FranciscoSan FranciscoUnited States
- Quantitative Biosciences Institute, University of California San FranciscoSan FranciscoUnited States
- Department of Pharmaceutical Chemistry, University of California San FranciscoSan FranciscoUnited States
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11
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McLean JT, Benny A, Nolan MD, Swinand G, Scanlan EM. Cysteinyl radicals in chemical synthesis and in nature. Chem Soc Rev 2021; 50:10857-10894. [PMID: 34397045 DOI: 10.1039/d1cs00254f] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Nature harnesses the unique properties of cysteinyl radical intermediates for a diverse range of essential biological transformations including DNA biosynthesis and repair, metabolism, and biological photochemistry. In parallel, the synthetic accessibility and redox chemistry of cysteinyl radicals renders them versatile reactive intermediates for use in a vast array of synthetic applications such as lipidation, glycosylation and fluorescent labelling of proteins, peptide macrocyclization and stapling, desulfurisation of peptides and proteins, and development of novel therapeutics. This review provides the reader with an overview of the role of cysteinyl radical intermediates in both chemical synthesis and biological systems, with a critical focus on mechanistic details. Direct insights from biological systems, where applied to chemical synthesis, are highlighted and potential avenues from nature which are yet to be explored synthetically are presented.
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Affiliation(s)
- Joshua T McLean
- Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse St., Dublin, D02 R590, Ireland.
| | - Alby Benny
- Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse St., Dublin, D02 R590, Ireland.
| | - Mark D Nolan
- Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse St., Dublin, D02 R590, Ireland.
| | - Glenna Swinand
- Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse St., Dublin, D02 R590, Ireland.
| | - Eoin M Scanlan
- Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse St., Dublin, D02 R590, Ireland.
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12
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Osterman IA, Dontsova OA, Sergiev PV. rRNA Methylation and Antibiotic Resistance. BIOCHEMISTRY (MOSCOW) 2021; 85:1335-1349. [PMID: 33280577 DOI: 10.1134/s000629792011005x] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Methylation of nucleotides in rRNA is one of the basic mechanisms of bacterial resistance to protein synthesis inhibitors. The genes for corresponding methyltransferases have been found in producer strains and clinical isolates of pathogenic bacteria. In some cases, rRNA methylation by housekeeping enzymes is, on the contrary, required for the action of antibiotics. The effects of rRNA modifications associated with antibiotic efficacy may be cooperative or mutually exclusive. Evolutionary relationships between the systems of rRNA modification by housekeeping enzymes and antibiotic resistance-related methyltransferases are of particular interest. In this review, we discuss the above topics in detail.
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Affiliation(s)
- I A Osterman
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo, 143028, Russia.,Faculty of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - O A Dontsova
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo, 143028, Russia.,Faculty of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia.,Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - P V Sergiev
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo, 143028, Russia. .,Faculty of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia.,Institute of Functional Genomics, Lomonosov Moscow State University, Moscow, 119991, Russia
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13
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Yoon S, Kim YB, Seo KW, Ha JS, Noh EB, Lee YJ. Characteristics of linezolid-resistant Enterococcus faecalis isolates from broiler breeder farms. Poult Sci 2020; 99:6055-6061. [PMID: 33142524 PMCID: PMC7647823 DOI: 10.1016/j.psj.2020.06.087] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 05/27/2020] [Accepted: 06/17/2020] [Indexed: 01/04/2023] Open
Abstract
Linezolid is an oxazolidinone class antibiotic used for treatment infections caused by various multidrug-resistant gram-positive pathogens including enterococci. However, recently, linezolid-resistant isolates in animals are considered as a human health hazard. In a broiler operation system, antimicrobial resistance can be transferred to the environment and commercial broiler via the fecal-oral route. Therefore, this study was conducted to investigate the prevalence and characteristics of linezolid-resistant Enterococcus faecalis (E. faecalis) from broiler parent stock in a broiler operation system. Among 297 E. faecalis isolates from 85 flocks in 8 broiler breeder farms, the prevalence of chloramphenicol- and linezolid-resistant isolates was 0 to 12.1% and 0 to 8.0%, respectively; however, there were no significant differences between farms. Therefore, a total of 14 (4.7%) chloramphenicol- and/or linezolid-resistant E. faecalis showed resistance to 7 or more antimicrobial classes. The drug-resistance gene optrA, which can confer resistance to linezolid, tedizolid, and phenicols, was found in 8 (2.69%) isolates, and 7 (2.36%) of the 8 optrA-positive isolates co-carried the phenicol exporter gene fexA. However, E. faecalis isolates from 3 of 8 broiler breeder farms only carried the optrA and/or fexA genes. As linezolid is one of the last antimicrobial treatments of choice for multidrug-resistant gram-positive pathogens including E. faecalis, the presence of antibiotic-resistant E. faecalis in broiler breeder farms should be monitored to prevent the introduction of linezolid-resistant strains to the food chain.
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Affiliation(s)
- Sunghyun Yoon
- College of Veterinary Medicine & Zoonoses Research Institute, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Yeong Bin Kim
- College of Veterinary Medicine & Zoonoses Research Institute, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Kwang Won Seo
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
| | - Jong Su Ha
- Quality Management Department, Samhwa GPS Breeding Agri. Inc., Hongseong 32291, Republic of Korea
| | - Eun Bi Noh
- College of Veterinary Medicine & Zoonoses Research Institute, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Young Ju Lee
- College of Veterinary Medicine & Zoonoses Research Institute, Kyungpook National University, Daegu 41566, Republic of Korea.
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14
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Abstract
Antibiotic resistance is mediated through several distinct mechanisms, most of which are relatively well understood and the clinical importance of which has long been recognized. Until very recently, neither of these statements was readily applicable to the class of resistance mechanism known as target protection, a phenomenon whereby a resistance protein physically associates with an antibiotic target to rescue it from antibiotic-mediated inhibition. In this Review, we summarize recent progress in understanding the nature and importance of target protection. In particular, we describe the molecular basis of the known target protection systems, emphasizing that target protection does not involve a single, uniform mechanism but is instead brought about in several mechanistically distinct ways.
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15
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Chajęcka-Wierzchowska W, Zadernowska A, García-Solache M. Ready-to-eat dairy products as a source of multidrug-resistant Enterococcus strains: Phenotypic and genotypic characteristics. J Dairy Sci 2020; 103:4068-4077. [DOI: 10.3168/jds.2019-17395] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Accepted: 01/16/2020] [Indexed: 12/22/2022]
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16
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Chen L, Han D, Tang Z, Hao J, Xiong W, Zeng Z. Co-existence of the oxazolidinone resistance genes cfr and optrA on two transferable multi-resistance plasmids in one Enterococcus faecalis isolate from swine. Int J Antimicrob Agents 2020; 56:105993. [PMID: 32335280 DOI: 10.1016/j.ijantimicag.2020.105993] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 02/12/2020] [Accepted: 04/15/2020] [Indexed: 02/06/2023]
Abstract
OBJECTIVES To identify and characterize oxazolidinone resistance genes cfr and optrA in enterococcal isolates. METHODS Two hundred and ninety-three enterococcal isolates were screened for the presence of cfr and optrA by polymerase chain reaction. The transferability of cfr and optrA was examined by conjugation. S1 nuclease pulsed-field gel electrophoresis and Southern blotting were used to identify the location of cfr and optrA. One Enterococcus faecalis isolate carrying both cfr and optrA was sequenced in full. RESULTS cfr and optrA were detected in 16 (5.5%) and 170 (58.0%) enterococcal isolates, respectively. Sixteen enterococcal isolates (E. faecalis n=13, Enterococcus avium n=2, Enterococcus mundtii n=1) carried both cfr and optrA. The cfr-carrying fragment between res and theta in plasmid p4 showed 98.9% identity to the corresponding region of plasmid pEF120805 from vancomycin-resistant Enterococcus faecium. The optrA-carrying segment between tnpB and optrA in plasmid p1 showed >99.9% identity to the corresponding region of genomic DNA from E. faecalis A101. Plasmid p4 and plasmid p1 were simultaneously conjugated to E. faecalis JH2-2. CONCLUSIONS One hundred and seventy optrA-positive enterococci were identified in 293 enterococcal isolates from swine and the farm environment. The co-existence of cfr and optrA in E. avium and E. mundtii has been identified previously. cfr and optrA were identified on two new conjugative plasmids from one E. faecalis isolate. The optrA-carrying segment (IS1216E-optrA-IS1216E) was reported initially. Among different types of enterococcal plasmids, ISEnfa5 and IS1216E elements may play a vital role in the dissemination of cfr and optrA, respectively.
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Affiliation(s)
- Lin Chen
- Guangdong Provincial Key Laboratory of Veterinary Drugs Development and Safety Evaluation, South China Agricultural University, Guangzhou, Guangdong, China; National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, South China Agricultural University, Guangzhou, Guangdong, China; National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
| | - Dongdong Han
- Guangdong Provincial Key Laboratory of Veterinary Drugs Development and Safety Evaluation, South China Agricultural University, Guangzhou, Guangdong, China; National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, South China Agricultural University, Guangzhou, Guangdong, China; National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
| | - Ziyun Tang
- Guangdong Provincial Key Laboratory of Veterinary Drugs Development and Safety Evaluation, South China Agricultural University, Guangzhou, Guangdong, China; National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, South China Agricultural University, Guangzhou, Guangdong, China; National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
| | - Jie Hao
- Guangdong Provincial Key Laboratory of Veterinary Drugs Development and Safety Evaluation, South China Agricultural University, Guangzhou, Guangdong, China; National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, South China Agricultural University, Guangzhou, Guangdong, China; National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
| | - Wenguang Xiong
- Guangdong Provincial Key Laboratory of Veterinary Drugs Development and Safety Evaluation, South China Agricultural University, Guangzhou, Guangdong, China; National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, South China Agricultural University, Guangzhou, Guangdong, China; National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China.
| | - Zhenling Zeng
- Guangdong Provincial Key Laboratory of Veterinary Drugs Development and Safety Evaluation, South China Agricultural University, Guangzhou, Guangdong, China; National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, South China Agricultural University, Guangzhou, Guangdong, China; National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China.
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17
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Gumkowski JD, Martinie RJ, Corrigan PS, Pan J, Bauerle MR, Almarei M, Booker SJ, Silakov A, Krebs C, Boal AK. Analysis of RNA Methylation by Phylogenetically Diverse Cfr Radical S-Adenosylmethionine Enzymes Reveals an Iron-Binding Accessory Domain in a Clostridial Enzyme. Biochemistry 2019; 58:3169-3184. [PMID: 31246421 DOI: 10.1021/acs.biochem.9b00197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cfr is a radical S-adenosylmethionine (SAM) RNA methylase linked to multidrug antibiotic resistance in bacterial pathogens. It catalyzes a chemically challenging C-C bond-forming reaction to methylate C8 of A2503 (Escherichia coli numbering) of 23S rRNA during ribosome assembly. The cfr gene has been identified as a mobile genetic element in diverse bacteria and in the genome of select Bacillales and Clostridiales species. Despite the importance of Cfr, few representatives have been purified and characterized in vitro. Here we show that Cfr homologues from Bacillus amyloliquefaciens, Enterococcus faecalis, Paenibacillus lautus, and Clostridioides difficile act as C8 adenine RNA methylases in biochemical assays. C. difficile Cfr contains an additional Cys-rich C-terminal domain that binds a mononuclear Fe2+ ion in a rubredoxin-type Cys4 motif. The C-terminal domain can be truncated with minimal impact on C. difficile Cfr activity, but the rate of turnover is decreased upon disruption of the Fe2+-binding site by Zn2+ substitution or ligand mutation. These findings indicate an important purpose for the observed C-terminal iron in the native fusion protein. Bioinformatic analysis of the C. difficile Cfr Cys-rich domain shows that it is widespread (∼1400 homologues) as a stand-alone gene in pathogenic or commensal Bacilli and Clostridia, with >10% encoded adjacent to a predicted radical SAM RNA methylase. Although the domain is not essential for in vitro C. difficile Cfr activity, the genomic co-occurrence and high abundance in the human microbiome suggest a possible functional role for a specialized rubredoxin in certain radical SAM RNA methylases that are relevant to human health.
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Affiliation(s)
- James D Gumkowski
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Ryan J Martinie
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Patrick S Corrigan
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Juan Pan
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Matthew R Bauerle
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Mohamed Almarei
- Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Squire J Booker
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States.,Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States.,Howard Hughes Medical Institute , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Alexey Silakov
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Carsten Krebs
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States.,Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Amie K Boal
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States.,Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
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18
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Na SH, Moon DC, Choi MJ, Oh SJ, Jung DY, Kang HY, Hyun BH, Lim SK. Detection of oxazolidinone and phenicol resistant enterococcal isolates from duck feces and carcasses. Int J Food Microbiol 2019; 293:53-59. [DOI: 10.1016/j.ijfoodmicro.2019.01.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 11/26/2018] [Accepted: 01/04/2019] [Indexed: 01/08/2023]
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19
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Molecules that Inhibit Bacterial Resistance Enzymes. Molecules 2018; 24:molecules24010043. [PMID: 30583527 PMCID: PMC6337270 DOI: 10.3390/molecules24010043] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 12/18/2018] [Accepted: 12/19/2018] [Indexed: 12/14/2022] Open
Abstract
Antibiotic resistance mediated by bacterial enzymes constitutes an unmet clinical challenge for public health, particularly for those currently used antibiotics that are recognized as "last-resort" defense against multidrug-resistant (MDR) bacteria. Inhibitors of resistance enzymes offer an alternative strategy to counter this threat. The combination of inhibitors and antibiotics could effectively prolong the lifespan of clinically relevant antibiotics and minimize the impact and emergence of resistance. In this review, we first provide a brief overview of antibiotic resistance mechanism by bacterial secreted enzymes. Furthermore, we summarize the potential inhibitors that sabotage these resistance pathways and restore the bactericidal activity of inactive antibiotics. Finally, the faced challenges and an outlook for the development of more effective and safer resistance enzyme inhibitors are discussed.
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20
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Aun E, Brauer A, Kisand V, Tenson T, Remm M. A k-mer-based method for the identification of phenotype-associated genomic biomarkers and predicting phenotypes of sequenced bacteria. PLoS Comput Biol 2018; 14:e1006434. [PMID: 30346947 PMCID: PMC6211763 DOI: 10.1371/journal.pcbi.1006434] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 11/01/2018] [Accepted: 08/15/2018] [Indexed: 11/18/2022] Open
Abstract
We have developed an easy-to-use and memory-efficient method called PhenotypeSeeker that (a) identifies phenotype-specific k-mers, (b) generates a k-mer-based statistical model for predicting a given phenotype and (c) predicts the phenotype from the sequencing data of a given bacterial isolate. The method was validated on 167 Klebsiella pneumoniae isolates (virulence), 200 Pseudomonas aeruginosa isolates (ciprofloxacin resistance) and 459 Clostridium difficile isolates (azithromycin resistance). The phenotype prediction models trained from these datasets obtained the F1-measure of 0.88 on the K. pneumoniae test set, 0.88 on the P. aeruginosa test set and 0.97 on the C. difficile test set. The F1-measures were the same for assembled sequences and raw sequencing data; however, building the model from assembled genomes is significantly faster. On these datasets, the model building on a mid-range Linux server takes approximately 3 to 5 hours per phenotype if assembled genomes are used and 10 hours per phenotype if raw sequencing data are used. The phenotype prediction from assembled genomes takes less than one second per isolate. Thus, PhenotypeSeeker should be well-suited for predicting phenotypes from large sequencing datasets. PhenotypeSeeker is implemented in Python programming language, is open-source software and is available at GitHub (https://github.com/bioinfo-ut/PhenotypeSeeker/).
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Affiliation(s)
- Erki Aun
- Department of Bioinformatics, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
- * E-mail:
| | - Age Brauer
- Department of Bioinformatics, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Veljo Kisand
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Tanel Tenson
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Maido Remm
- Department of Bioinformatics, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
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21
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A high incidence and coexistence of multiresistance genes cfr and optrA among linezolid-resistant enterococci isolated from a teaching hospital in Wenzhou, China. Eur J Clin Microbiol Infect Dis 2018; 37:1441-1448. [DOI: 10.1007/s10096-018-3269-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 04/30/2018] [Indexed: 02/04/2023]
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22
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Stojković V, Chu T, Therizols G, Weinberg DE, Fujimori DG. miCLIP-MaPseq, a Substrate Identification Approach for Radical SAM RNA Methylating Enzymes. J Am Chem Soc 2018; 140:7135-7143. [PMID: 29782154 DOI: 10.1021/jacs.8b02618] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Although present across bacteria, the large family of radical SAM RNA methylating enzymes is largely uncharacterized. Escherichia coli RlmN, the founding member of the family, methylates an adenosine in 23S rRNA and several tRNAs to yield 2-methyladenosine (m2A). However, varied RNA substrate specificity among RlmN enzymes, combined with the ability of certain family members to generate 8-methyladenosine (m8A), makes functional predictions across this family challenging. Here, we present a method for unbiased substrate identification that exploits highly efficient, mechanism-based cross-linking between the enzyme and its RNA substrates. Additionally, by determining that the thermostable group II intron reverse transcriptase introduces mismatches at the site of the cross-link, we have identified the precise positions of RNA modification using mismatch profiling. These results illustrate the capability of our method to define enzyme-substrate pairs and determine modification sites of the largely uncharacterized radical SAM RNA methylating enzyme family.
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Affiliation(s)
- Vanja Stojković
- Department of Cellular and Molecular Pharmacology , University of California , San Francisco , California 94158 , United States
| | - Tongyue Chu
- Department of Cellular and Molecular Pharmacology , University of California , San Francisco , California 94158 , United States
| | - Gabriel Therizols
- Department of Cellular and Molecular Pharmacology , University of California , San Francisco , California 94158 , United States
| | - David E Weinberg
- Department of Cellular and Molecular Pharmacology , University of California , San Francisco , California 94158 , United States
| | - Danica Galonić Fujimori
- Department of Cellular and Molecular Pharmacology , University of California , San Francisco , California 94158 , United States.,Department of Pharmaceutical Chemistry , University of California , 600 16th Street, MC2280 San Francisco , California 94158 , United States
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23
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Boriack-Sjodin PA, Ribich S, Copeland RA. RNA-modifying proteins as anticancer drug targets. Nat Rev Drug Discov 2018; 17:435-453. [PMID: 29773918 DOI: 10.1038/nrd.2018.71] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
All major biological macromolecules (DNA, RNA, proteins and lipids) undergo enzyme-catalysed covalent modifications that impact their structure, function and stability. A variety of covalent modifications of RNA have been identified and demonstrated to affect RNA stability and translation to proteins; these mechanisms of translational control have been termed epitranscriptomics. Emerging data suggest that some epitranscriptomic mechanisms are altered in human cancers as well as other human diseases. In this Review, we examine the current understanding of RNA modifications with a focus on mRNA methylation, highlight their possible roles in specific cancer indications and discuss the emerging potential of RNA-modifying proteins as therapeutic targets.
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24
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Bensaci M, Flanagan S, Sandison T. Determination of Tedizolid susceptibility interpretive criteria for gram-positive pathogens according to clinical and laboratory standards institute guidelines. Diagn Microbiol Infect Dis 2017; 90:214-220. [PMID: 29277464 DOI: 10.1016/j.diagmicrobio.2017.10.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 10/26/2017] [Accepted: 10/29/2017] [Indexed: 01/05/2023]
Abstract
For effective antibacterial therapy, physicians require qualitative test results using susceptibility breakpoints provided by clinical microbiology laboratories. This article summarizes the key components used to establish the Clinical Laboratory Standards Institute (CLSI) breakpoints for tedizolid. First, in vitro studies using recent surveillance and clinical trial isolates ascertained minimal inhibitory concentration (MIC) distributions against pertinent organisms, including staphylococci, streptococci, and enterococci. Studies in animal models of infection determined rates of antibacterial efficacy and survival following administration of tedizolid phosphate at doses equivalent to those in humans. Pharmacokinetic and pharmacodynamic analyses examined the relationship between plasma concentrations and MICs against the target organism. Finally, clinical trials assessed clinical and microbiologic outcomes by MIC. All these data were evaluated and combined to obtain the ratified CLSI susceptibility criteria for tedizolid of ≤0.5μg/mL for Staphylococcus aureus, Streptococcus pyogenes, Streptococcus agalactiae, and Enterococcus faecalis and ≤0.25μg/mL for Streptococcus anginosus group.
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25
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Currie MA, Brown G, Wong A, Ohira T, Sugiyama K, Suzuki T, Yakunin AF, Jia Z. Structural and functional characterization of the TYW3/Taw3 class of SAM-dependent methyltransferases. RNA (NEW YORK, N.Y.) 2017; 23:346-354. [PMID: 27932585 PMCID: PMC5311493 DOI: 10.1261/rna.057943.116] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 11/25/2016] [Indexed: 06/01/2023]
Abstract
S-adenosylmethionine (SAM)-dependent methyltransferases regulate a wide range of biological processes through the modification of proteins, nucleic acids, polysaccharides, as well as various metabolites. TYW3/Taw3 is a SAM-dependent methyltransferase responsible for the formation of a tRNA modification known as wybutosine and its derivatives that are required for accurate decoding in protein synthesis. Here, we report the crystal structure of Taw3, a homolog of TYW3 from Sulfolobus solfataricus, which revealed a novel α/β fold. The sequence motif (S/T)xSSCxGR and invariant aspartate and histidine, conserved in TYW3/Taw3, cluster to form the catalytic center. These structural and sequence features indicate that TYW3/Taw3 proteins constitute a distinct class of SAM-dependent methyltransferases. Using site-directed mutagenesis along with in vivo complementation assays combined with mass spectrometry as well as ligand docking and cofactor binding assays, we have identified the active site of TYW3 and residues essential for cofactor binding and methyltransferase activity.
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Affiliation(s)
- Mark A Currie
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Greg Brown
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Andrew Wong
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Takayuki Ohira
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Kei Sugiyama
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Alexander F Yakunin
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Zongchao Jia
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
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26
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Tamang MD, Moon DC, Kim SR, Kang HY, Lee K, Nam HM, Jang GC, Lee HS, Jung SC, Lim SK. Detection of novel oxazolidinone and phenicol resistance gene optrA in enterococcal isolates from food animals and animal carcasses. Vet Microbiol 2017; 201:252-256. [DOI: 10.1016/j.vetmic.2017.01.035] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 01/24/2017] [Accepted: 01/30/2017] [Indexed: 10/20/2022]
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27
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Transfer RNA methyltransferases with a SpoU-TrmD (SPOUT) fold and their modified nucleosides in tRNA. Biomolecules 2017; 7:biom7010023. [PMID: 28264529 PMCID: PMC5372735 DOI: 10.3390/biom7010023] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Accepted: 02/23/2017] [Indexed: 11/22/2022] Open
Abstract
The existence of SpoU-TrmD (SPOUT) RNA methyltransferase superfamily was first predicted by bioinformatics. SpoU is the previous name of TrmH, which catalyzes the 2’-O-methylation of ribose of G18 in tRNA; TrmD catalyzes the formation of N1-methylguanosine at position 37 in tRNA. Although SpoU (TrmH) and TrmD were originally considered to be unrelated, the bioinformatics study suggested that they might share a common evolution origin and form a single superfamily. The common feature of SPOUT RNA methyltransferases is the formation of a deep trefoil knot in the catalytic domain. In the past decade, the SPOUT RNA methyltransferase superfamily has grown; furthermore, knowledge concerning the functions of their modified nucleosides in tRNA has also increased. Some enzymes are potential targets in the design of anti-bacterial drugs. In humans, defects in some genes may be related to carcinogenesis. In this review, recent findings on the tRNA methyltransferases with a SPOUT fold and their methylated nucleosides in tRNA, including classification of tRNA methyltransferases with a SPOUT fold; knot structures, domain arrangements, subunit structures and reaction mechanisms; tRNA recognition mechanisms, and functions of modified nucleosides synthesized by this superfamily, are summarized. Lastly, the future perspective for studies on tRNA modification enzymes are considered.
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28
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Tang Y, Dai L, Sahin O, Wu Z, Liu M, Zhang Q. Emergence of a plasmid-borne multidrug resistance gene cfr(C) in foodborne pathogen Campylobacter. J Antimicrob Chemother 2017; 72:1581-1588. [DOI: 10.1093/jac/dkx023] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 01/15/2017] [Indexed: 12/22/2022] Open
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29
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Surveillance of tedizolid activity and resistance: In vitro susceptibility of Gram-positive pathogens collected over 5 years from the United States and Europe. Diagn Microbiol Infect Dis 2017; 87:133-138. [DOI: 10.1016/j.diagmicrobio.2016.10.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 09/08/2016] [Accepted: 10/03/2016] [Indexed: 11/19/2022]
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30
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Drouin A, Giguère S, Déraspe M, Marchand M, Tyers M, Loo VG, Bourgault AM, Laviolette F, Corbeil J. Predictive computational phenotyping and biomarker discovery using reference-free genome comparisons. BMC Genomics 2016; 17:754. [PMID: 27671088 PMCID: PMC5037627 DOI: 10.1186/s12864-016-2889-6] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Accepted: 07/06/2016] [Indexed: 12/14/2022] Open
Abstract
Background The identification of genomic biomarkers is a key step towards improving diagnostic tests and therapies. We present a reference-free method for this task that relies on a k-mer representation of genomes and a machine learning algorithm that produces intelligible models. The method is computationally scalable and well-suited for whole genome sequencing studies. Results The method was validated by generating models that predict the antibiotic resistance of C. difficile, M. tuberculosis, P. aeruginosa, and S. pneumoniae for 17 antibiotics. The obtained models are accurate, faithful to the biological pathways targeted by the antibiotics, and they provide insight into the process of resistance acquisition. Moreover, a theoretical analysis of the method revealed tight statistical guarantees on the accuracy of the obtained models, supporting its relevance for genomic biomarker discovery. Conclusions Our method allows the generation of accurate and interpretable predictive models of phenotypes, which rely on a small set of genomic variations. The method is not limited to predicting antibiotic resistance in bacteria and is applicable to a variety of organisms and phenotypes. Kover, an efficient implementation of our method, is open-source and should guide biological efforts to understand a plethora of phenotypes (http://github.com/aldro61/kover/). Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2889-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alexandre Drouin
- Department of Computer Science and Software Engineering, Université Laval, Québec, Canada.
| | - Sébastien Giguère
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Canada
| | - Maxime Déraspe
- Department of Molecular Medicine, Université Laval, Québec, Canada
| | - Mario Marchand
- Department of Computer Science and Software Engineering, Université Laval, Québec, Canada.,Big Data Research Centre, Université Laval, Québec, Canada
| | - Michael Tyers
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Canada
| | - Vivian G Loo
- Division of Infectious Diseases, Departments of Medicine and Microbiology, McGill University Health Centre, Montréal, Canada.,Department of Medicine, McGill University, Montréal, Canada
| | - Anne-Marie Bourgault
- Division of Infectious Diseases, Departments of Medicine and Microbiology, McGill University Health Centre, Montréal, Canada.,Department of Medicine, McGill University, Montréal, Canada
| | - François Laviolette
- Department of Computer Science and Software Engineering, Université Laval, Québec, Canada.,Big Data Research Centre, Université Laval, Québec, Canada
| | - Jacques Corbeil
- Department of Molecular Medicine, Université Laval, Québec, Canada.,Big Data Research Centre, Université Laval, Québec, Canada
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31
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Chen Y, Zou T, McCormick S. S-Adenosylmethionine Synthetase 3 Is Important for Pollen Tube Growth. PLANT PHYSIOLOGY 2016; 172:244-53. [PMID: 27482079 PMCID: PMC5074607 DOI: 10.1104/pp.16.00774] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 07/30/2016] [Indexed: 05/03/2023]
Abstract
S-Adenosylmethionine is widely used in a variety of biological reactions and participates in the methionine (Met) metabolic pathway. In Arabidopsis (Arabidopsis thaliana), one of the four S-adenosylmethionine synthetase genes, METHIONINE ADENOSYLTRANSFERASE3 (MAT3), is highly expressed in pollen. Here, we show that mat3 mutants have impaired pollen tube growth and reduced seed set. Metabolomics analyses confirmed that mat3 pollen and pollen tubes overaccumulate Met and that mat3 pollen has several metabolite profiles, such as those of polyamine biosynthesis, which are different from those of the wild type. Additionally, we show that disruption of Met metabolism in mat3 pollen affected transfer RNA and histone methylation levels. Thus, our results suggest a connection between metabolism and epigenetics.
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Affiliation(s)
- Yuan Chen
- Plant Gene Expression Center, United States Department of Agriculture-Agricultural Research Service, and Department of Plant and Microbial Biology, University of California Berkeley, Albany, California 94710
| | - Ting Zou
- Plant Gene Expression Center, United States Department of Agriculture-Agricultural Research Service, and Department of Plant and Microbial Biology, University of California Berkeley, Albany, California 94710
| | - Sheila McCormick
- Plant Gene Expression Center, United States Department of Agriculture-Agricultural Research Service, and Department of Plant and Microbial Biology, University of California Berkeley, Albany, California 94710
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32
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Stojković V, Noda-Garcia L, Tawfik DS, Fujimori DG. Antibiotic resistance evolved via inactivation of a ribosomal RNA methylating enzyme. Nucleic Acids Res 2016; 44:8897-8907. [PMID: 27496281 PMCID: PMC5062987 DOI: 10.1093/nar/gkw699] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 07/28/2016] [Indexed: 12/11/2022] Open
Abstract
Modifications of the bacterial ribosome regulate the function of the ribosome and modulate its susceptibility to antibiotics. By modifying a highly conserved adenosine A2503 in 23S rRNA, methylating enzyme Cfr confers resistance to a range of ribosome-targeting antibiotics. The same adenosine is also methylated by RlmN, an enzyme widely distributed among bacteria. While RlmN modifies C2, Cfr modifies the C8 position of A2503. Shared nucleotide substrate and phylogenetic relationship between RlmN and Cfr prompted us to investigate evolutionary origin of antibiotic resistance in this enzyme family. Using directed evolution of RlmN under antibiotic selection, we obtained RlmN variants that mediate low-level resistance. Surprisingly, these variants confer resistance not through the Cfr-like C8 methylation, but via inhibition of the endogenous RlmN C2 methylation of A2503. Detection of RlmN inactivating mutations in clinical resistance isolates suggests that the mechanism used by the in vitro evolved variants is also relevant in a clinical setting. Additionally, as indicated by a phylogenetic analysis, it appears that Cfr did not diverge from the RlmN family but from another distinct family of predicted radical SAM methylating enzymes whose function remains unknown.
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Affiliation(s)
- Vanja Stojković
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA 94158, USA
| | - Lianet Noda-Garcia
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Dan S Tawfik
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Danica Galonić Fujimori
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA 94158, USA Department of Pharmaceutical Chemistry, University of California San Francisco, 600 16th St, MC2280 San Francisco, CA 94158, USA
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33
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Nomenclature and functionality of the so-called cfr gene from Clostridium difficile. Antimicrob Agents Chemother 2016; 59:2476-7. [PMID: 25762794 DOI: 10.1128/aac.04893-14] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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34
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Ntokou E, Hansen LH, Kongsted J, Vester B. Biochemical and Computational Analysis of the Substrate Specificities of Cfr and RlmN Methyltransferases. PLoS One 2015; 10:e0145655. [PMID: 26700482 PMCID: PMC4689488 DOI: 10.1371/journal.pone.0145655] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 12/07/2015] [Indexed: 12/15/2022] Open
Abstract
Cfr and RlmN methyltransferases both modify adenine 2503 in 23S rRNA (Escherichia coli numbering). RlmN methylates position C2 of adenine while Cfr methylates position C8, and to a lesser extent C2, conferring antibiotic resistance to peptidyl transferase inhibitors. Cfr and RlmN show high sequence homology and may be evolutionarily linked to a common ancestor. To explore their individual specificity and similarity we performed two sets of experiments. We created a homology model of Cfr and explored the C2/C8 specificity using docking and binding energy calculations on the Cfr homology model and an X-ray structure of RlmN. We used a trinucleotide as target sequence and assessed its positioning at the active site for methylation. The calculations are in accordance with different poses of the trinucleotide in the two enzymes indicating major evolutionary changes to shift the C2/C8 specificities. To explore interchangeability between Cfr and RlmN we constructed various combinations of their genes. The function of the mixed genes was investigated by RNA primer extension analysis to reveal methylation at 23S rRNA position A2503 and by MIC analysis to reveal antibiotic resistance. The catalytic site is expected to be responsible for the C2/C8 specificity and most of the combinations involve interchanging segments at this site. Almost all replacements showed no function in the primer extension assay, apart from a few that had a weak effect. Thus Cfr and RlmN appear to be much less similar than expected from their sequence similarity and common target.
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Affiliation(s)
- Eleni Ntokou
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
- * E-mail:
| | - Lykke Haastrup Hansen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Jacob Kongsted
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | - Birte Vester
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
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35
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Detection of a New cfr-Like Gene, cfr(B), in Enterococcus faecium Isolates Recovered from Human Specimens in the United States as Part of the SENTRY Antimicrobial Surveillance Program. Antimicrob Agents Chemother 2015; 59:6256-61. [PMID: 26248384 DOI: 10.1128/aac.01473-15] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 07/19/2015] [Indexed: 12/23/2022] Open
Abstract
Two linezolid-resistant Enterococcus faecium isolates (MICs, 8 μg/ml) from unique patients of a medical center in New Orleans were included in this study. Isolates were initially investigated for the presence of mutations in the V domain of 23S rRNA genes and L3, L4, and L22 ribosomal proteins, as well as cfr. Isolates were subjected to pulsed-field gel electrophoresis (just one band difference), and one representative strain was submitted to whole-genome sequencing. Gene location was also determined by hybridization, and cfr genes were cloned and expressed in a Staphylococcus aureus background. The two isolates had one out of six 23S rRNA alleles mutated (G2576T), had wild-type L3, L4, and L22 sequences, and were positive for a cfr-like gene. The sequence of the protein encoded by the cfr-like gene was most similar (99.7%) to that found in Peptoclostridium difficile, which shared only 74.9% amino acid identity with the proteins encoded by genes previously identified in staphylococci and non-faecium enterococci and was, therefore, denominated Cfr(B). When expressed in S. aureus, the protein conferred a resistance profile similar to that of Cfr. Two copies of cfr(B) were chromosomally located and embedded in a Tn6218 similar to the cfr-carrying transposon described in P. difficile. This study reports the first detection of cfr genes in E. faecium clinical isolates in the United States and characterization of a new cfr variant, cfr(B). cfr(B) has been observed in mobile genetic elements in E. faecium and P. difficile, suggesting potential for dissemination. However, further analysis is necessary to access the resistance levels conferred by cfr(B) when expressed in enterococci.
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36
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Bauerle MR, Schwalm EL, Booker SJ. Mechanistic diversity of radical S-adenosylmethionine (SAM)-dependent methylation. J Biol Chem 2015; 290:3995-4002. [PMID: 25477520 PMCID: PMC4326810 DOI: 10.1074/jbc.r114.607044] [Citation(s) in RCA: 179] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Radical S-adenosylmethionine (SAM) enzymes use the oxidizing power of a 5'-deoxyadenosyl 5'-radical to initiate an amazing array of transformations, usually through the abstraction of a target substrate hydrogen atom. A common reaction of radical SAM (RS) enzymes is the methylation of unactivated carbon or phosphorous atoms found in numerous primary and secondary metabolites, as well as in proteins, sugars, lipids, and RNA. However, neither the chemical mechanisms by which these unactivated atoms obtain methyl groups nor the actual methyl donors are conserved. In fact, RS methylases have been grouped into three classes based on protein architecture, cofactor requirement, and predicted mechanism of catalysis. Class A methylases use two cysteine residues to methylate sp(2)-hybridized carbon centers. Class B methylases require a cobalamin cofactor to methylate both sp(2)-hybridized and sp(3)-hybridized carbon centers as well as phosphinate phosphorous atoms. Class C methylases share significant sequence homology with the RS enzyme, HemN, and may bind two SAM molecules simultaneously to methylate sp(2)-hybridized carbon centers. Lastly, we describe a new class of recently discovered RS methylases. These Class D methylases, unlike Class A, B, and C enzymes, which use SAM as the source of the donated methyl carbon, are proposed to methylate sp(2)-hybridized carbon centers using methylenetetrahydrofolate as the source of the appended methyl carbon.
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Affiliation(s)
- Matthew R Bauerle
- From the Department of Chemistry and the Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802
| | - Erica L Schwalm
- From the Department of Chemistry and the Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802
| | - Squire J Booker
- From the Department of Chemistry and the Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802
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37
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Sahm DF, Deane J, Bien PA, Locke JB, Zuill DE, Shaw KJ, Bartizal KF. Results of the Surveillance of Tedizolid Activity and Resistance Program: in vitro susceptibility of Gram-positive pathogens collected in 2011 and 2012 from the United States and Europe. Diagn Microbiol Infect Dis 2015; 81:112-8. [DOI: 10.1016/j.diagmicrobio.2014.08.011] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 08/22/2014] [Accepted: 08/23/2014] [Indexed: 10/24/2022]
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38
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Takaya A, Kimura A, Sato Y, Ishiwada N, Watanabe M, Matsui M, Shibayama K, Yamamoto T. Molecular characterization of linezolid-resistant CoNS isolates in Japan. J Antimicrob Chemother 2014; 70:658-63. [PMID: 25381168 DOI: 10.1093/jac/dku443] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
OBJECTIVES Linezolid has been reported to remain active against 98% of staphylococci with resistance identified in 0.05% of Staphylococcus aureus and 1.4% of CoNS. The objective of this study was to characterize the linezolid-resistance mechanisms in the linezolid-resistant CoNS strains isolated in Japan. METHODS Staphylococcus capitis strains exhibiting linezolid MICs >8 mg/L isolated from inpatients between 2012 and 2014 were screened for cfr and mutations in 23S rRNA, L3 and L4 by PCR/sequencing. Isolates were also examined for mutations in the rlmN gene. RESULTS S. capitis had six 23S rRNA alleles. Five S. capitis isolates displayed linezolid MICs of 8, 16 and 32 mg/L. G2576U mutations were detected in three, four or five copies of 23S rRNA in all isolates. In two isolates exhibiting the highest linezolid MIC (32 mg/L) there was a large deletion in a single copy of 23S rRNA. Repeated 10 bp sequences were found in both 16S and 23S rRNAs, suggesting deletion by recombination between the repeats. One isolate had the mutation Ala-142→Thr in the ribosomal protein L3. All linezolid-resistant isolates also demonstrated mutations in the gene encoding RlmN methyltransferase, leading to Thr-62→Met and Gly-148→Ser. CONCLUSIONS Multiple mechanisms appeared to be responsible for the elevated linezolid resistance in S. capitis isolates: a G2576U mutation in different numbers of copies of 23S rRNA, loss of a single copy of 23S rRNA and a mutation in the ribosomal protein L3, suggesting the accumulation of independent mutational events.
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Affiliation(s)
- Akiko Takaya
- Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| | - Asahi Kimura
- Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| | - Yoshiharu Sato
- Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| | - Naruhiko Ishiwada
- Division of Control and Treatment of Infectious Diseases, Chiba University Hospital, Chiba 260-8677, Japan
| | - Masaharu Watanabe
- Division of Laboratory Medicine, Chiba University Hospital, Chiba 260-8677, Japan
| | - Mari Matsui
- Department of Bacteriology II, National Institute of Infectious Diseases, Musashimurayama, Tokyo 208-0011, Japan
| | - Keigo Shibayama
- Department of Bacteriology II, National Institute of Infectious Diseases, Musashimurayama, Tokyo 208-0011, Japan
| | - Tomoko Yamamoto
- Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
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39
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Kimura S, Miyauchi K, Ikeuchi Y, Thiaville PC, Crécy-Lagard VD, Suzuki T. Discovery of the β-barrel-type RNA methyltransferase responsible for N6-methylation of N6-threonylcarbamoyladenosine in tRNAs. Nucleic Acids Res 2014; 42:9350-65. [PMID: 25063302 PMCID: PMC4132733 DOI: 10.1093/nar/gku618] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Methylation is a versatile reaction involved in the synthesis and modification of biologically active molecules, including RNAs. N(6)-methyl-threonylcarbamoyl adenosine (m(6)t(6)A) is a post-transcriptional modification found at position 37 of tRNAs from bacteria, insect, plants, and mammals. Here, we report that in Escherichia coli, yaeB (renamed as trmO) encodes a tRNA methyltransferase responsible for the N(6)-methyl group of m(6)t(6)A in tRNA(Thr) specific for ACY codons. TrmO has a unique single-sheeted β-barrel structure and does not belong to any known classes of methyltransferases. Recombinant TrmO employs S-adenosyl-L-methionine (AdoMet) as a methyl donor to methylate t(6)A to form m(6)t(6)A in tRNA(Thr). Therefore, TrmO/YaeB represents a novel category of AdoMet-dependent methyltransferase (Class VIII). In a ΔtrmO strain, m(6)t(6)A was converted to cyclic t(6)A (ct(6)A), suggesting that t(6)A is a common precursor for both m(6)t(6)A and ct(6)A. Furthermore, N(6)-methylation of t(6)A enhanced the attenuation activity of the thr operon, suggesting that TrmO ensures efficient decoding of ACY. We also identified a human homolog, TRMO, indicating that m(6)t(6)A plays a general role in fine-tuning of decoding in organisms from bacteria to mammals.
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Affiliation(s)
- Satoshi Kimura
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kenjyo Miyauchi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Yoshiho Ikeuchi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Patrick C Thiaville
- Genetics and Genomics Graduate Program University of Florida Genetics Institute Department of Microbiology, University of Florida, Gainesville, Florida 32611-0700, USA Institut de Génétique et Microbiologie, Université of Paris-Sud, Orsay, France
| | - Valérie de Crécy-Lagard
- University of Florida Genetics Institute Department of Microbiology, University of Florida, Gainesville, Florida 32611-0700, USA
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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40
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Silakov A, Grove TL, Radle MI, Bauerle M, Green MT, Rosenzweig AC, Boal AK, Booker SJ. Characterization of a cross-linked protein-nucleic acid substrate radical in the reaction catalyzed by RlmN. J Am Chem Soc 2014; 136:8221-8. [PMID: 24806349 PMCID: PMC4227720 DOI: 10.1021/ja410560p] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Indexed: 11/28/2022]
Abstract
RlmN and Cfr are methyltransferases/methylsynthases that belong to the radical S-adenosylmethionine superfamily of enzymes. RlmN catalyzes C2 methylation of adenosine 2503 (A2503) of 23S rRNA, while Cfr catalyzes C8 methylation of the exact same nucleotide, and will subsequently catalyze C2 methylation if the site is unmethylated. A key feature of the unusual mechanisms of catalysis proposed for these enzymes is the attack of a methylene radical, derived from a methylcysteine residue, onto the carbon center undergoing methylation to generate a paramagnetic protein-nucleic acid cross-linked species. This species has been thoroughly characterized during Cfr-dependent C8 methylation, but does not accumulate to detectible levels in RlmN-dependent C2 methylation. Herein, we show that inactive C118S/A variants of RlmN accumulate a substrate-derived paramagnetic species. Characterization of this species by electron paramagnetic resonance spectroscopy in concert with strategic isotopic labeling shows that the radical is delocalized throughout the adenine ring of A2503, although predominant spin density is on N1 and N3. Moreover, (13)C hyperfine interactions between the radical and the methylene carbon of the formerly [methyl-(13)C]Cys355 residue show that the radical species exists in a covalent cross-link between the protein and the nucleic acid substrate. X-ray structures of RlmN C118A show that, in the presence of SAM, the substitution does not alter the active site structure compared to that of the wild-type enzyme. Together, these findings have new mechanistic implications for the role(s) of C118 and its counterpart in Cfr (C105) in catalysis, and suggest involvement of the residue in resolution of the cross-linked species via a radical mediated process.
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Affiliation(s)
- Alexey Silakov
- Department of Chemistry, and Department of
Biochemistry and Molecular Biology, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Tyler L. Grove
- Department of Chemistry, and Department of
Biochemistry and Molecular Biology, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Matthew I. Radle
- Department of Chemistry, and Department of
Biochemistry and Molecular Biology, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Matthew
R. Bauerle
- Department of Chemistry, and Department of
Biochemistry and Molecular Biology, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Michael T. Green
- Department of Chemistry, and Department of
Biochemistry and Molecular Biology, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Amy C. Rosenzweig
- Departments
of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Amie K. Boal
- Department of Chemistry, and Department of
Biochemistry and Molecular Biology, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Departments
of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Squire J. Booker
- Department of Chemistry, and Department of
Biochemistry and Molecular Biology, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
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41
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Broderick JB, Duffus B, Duschene KS, Shepard EM. Radical S-adenosylmethionine enzymes. Chem Rev 2014; 114:4229-317. [PMID: 24476342 PMCID: PMC4002137 DOI: 10.1021/cr4004709] [Citation(s) in RCA: 584] [Impact Index Per Article: 58.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Indexed: 12/22/2022]
Affiliation(s)
- Joan B. Broderick
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Benjamin
R. Duffus
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Kaitlin S. Duschene
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Eric M. Shepard
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
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Patel SN, Memari N, Shahinas D, Toye B, Jamieson FB, Farrell DJ. Linezolid resistance in Enterococcus faecium isolated in Ontario, Canada. Diagn Microbiol Infect Dis 2013; 77:350-3. [DOI: 10.1016/j.diagmicrobio.2013.08.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 08/15/2013] [Accepted: 08/21/2013] [Indexed: 10/26/2022]
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Liu Y, Wang Y, Schwarz S, Wang S, Chen L, Wu C, Shen J. Investigation of a multiresistance gene cfr that fails to mediate resistance to phenicols and oxazolidinones in Enterococcus faecalis. J Antimicrob Chemother 2013; 69:892-8. [DOI: 10.1093/jac/dkt459] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Culver GM, Rife JP. Involvement of Ribosome Biogenesis in Antibiotic Function, Acquired Resistance, and Future Opportunities in Drug Discovery. Antibiotics (Basel) 2013. [DOI: 10.1002/9783527659685.ch15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Fujimori DG. Radical SAM-mediated methylation reactions. Curr Opin Chem Biol 2013; 17:597-604. [PMID: 23835516 DOI: 10.1016/j.cbpa.2013.05.032] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 05/28/2013] [Indexed: 10/26/2022]
Abstract
A subset of enzymes that belong to the radical S-adenosylmethionine (SAM) superfamily is able to catalyze methylation reactions. Substrates of these enzymes are distinct from the nucleophilic substrates that undergo methylation by a polar mechanism. Recently, activities of several radical SAM methylating enzymes have been reconstituted in vitro and their mechanisms of catalysis investigated. The RNA modifying enzymes RlmN and Cfr catalyze methylation via a methyl synthase mechanism. These enzymes use SAM in two distinct roles: as a source of a methyl group transferred to a conserved cysteine and as a source of 5'-deoxyadenosyl radical (5'-dA). Hydrogen atom abstraction by this species generates a thiomethylene radical which adds into the RNA substrate, forming an enzyme-substrate covalent adduct. In another recent study, methylation of the indole moiety of tryptophan by the radical SAM and cobalamin-binding domain enzyme TsrM has been reconstituted. Methylcobalamin serves as an intermediate methyl donor in TsrM, and is proposed to transfer the methyl group as a methyl radical. Interestingly, despite the presence of the radical SAM motif, no reductive cleavage of SAM has been observed in this methylation. These important reconstitutions set the stage for further studies on mechanisms of radical methylation.
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Affiliation(s)
- Danica Galonić Fujimori
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158-2280, USA.
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Distinction between the Cfr methyltransferase conferring antibiotic resistance and the housekeeping RlmN methyltransferase. Antimicrob Agents Chemother 2013; 57:4019-26. [PMID: 23752511 DOI: 10.1128/aac.00448-13] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The cfr gene encodes the Cfr methyltransferase that primarily methylates C-8 in A2503 of 23S rRNA in the peptidyl transferase region of bacterial ribosomes. The methylation provides resistance to six classes of antibiotics of clinical and veterinary importance. The rlmN gene encodes the RlmN methyltransferase that methylates C-2 in A2503 in 23S rRNA and A37 in tRNA, but RlmN does not significantly influence antibiotic resistance. The enzymes are homologous and use the same mechanism involving radical S-adenosyl methionine to methylate RNA via an intermediate involving a methylated cysteine in the enzyme and a transient cross-linking to the RNA, but they differ in which carbon atom in the adenine they methylate. Comparative sequence analysis identifies differentially conserved residues that indicate functional sequence divergence between the two classes of Cfr- and RlmN-like sequences. The differentiation between the two classes is supported by previous and new experimental evidence from antibiotic resistance, primer extensions, and mass spectrometry. Finally, evolutionary aspects of the distribution of Cfr- and RlmN-like enzymes are discussed.
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Grove TL, Livada J, Schwalm EL, Green MT, Booker SJ, Silakov A. A substrate radical intermediate in catalysis by the antibiotic resistance protein Cfr. Nat Chem Biol 2013; 9:422-7. [PMID: 23644479 PMCID: PMC3897224 DOI: 10.1038/nchembio.1251] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 04/02/2013] [Indexed: 01/08/2023]
Abstract
Cfr-dependent methylation of C8 of adenosine 2503 (A2503) in 23S rRNA confers bacterial resistance to an array of clinically important antibiotics that target the large subunit of the ribosome, including the synthetic oxazolidinone antibiotic linezolid. The key element of the proposed mechanism for Cfr, a radical S-adenosylmethionine (SAM) enzyme, is the addition of a methylene radical — generated by hydrogen-atom abstraction from the methyl group of an S-methylated cysteine residue (mCys) — onto C8 of A2503 to form a protein – nucleic acid cross-linked species containing an unpaired electron. Herein we use continuous-wave and pulsed electron paramagnetic resonance (EPR) techniques to provide direct spectroscopic evidence for this intermediate, showing a spin-delocalized radical with maximum spin density at N7 of the adenine ring. In addition, we use rapid-freeze quench EPR to show that the radical forms and decays with rate constants that are consistent with the rate of formation of the methylated product.
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Affiliation(s)
- Tyler L Grove
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania, USA
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Diaz L, Kontoyiannis DP, Panesso D, Albert ND, Singh KV, Tran TT, Munita JM, Murray BE, Arias CA. Dissecting the mechanisms of linezolid resistance in a Drosophila melanogaster infection model of Staphylococcus aureus. J Infect Dis 2013; 208:83-91. [PMID: 23547139 DOI: 10.1093/infdis/jit138] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Mini-host models are simple experimental systems to study host-pathogen interactions. We adapted a Drosophila melanogaster infection model to evaluate the in vivo effect of different mechanisms of linezolid (LNZ) resistance in Staphylococcus aureus. METHODS Fly survival was evaluated after infection with LNZ-resistant S. aureus strains NRS119 (which has mutations in 23S ribosomal RNA [rRNA]), CM-05 and 004-737X (which carry cfr), LNZ-susceptible derivatives of CM-05 and 004-737X (which lack cfr), and ATCC 29213 (an LNZ-susceptible control). Flies were then fed food mixed with LNZ (concentration, 15-500 µg/mL). Results were compared to those in mouse peritonitis, using LNZ via oral gavage at 80 and 120 mg/kg every 12 hours. RESULTS LNZ at 500 µg/mL in fly food protected against all strains, while concentrations of 15-250 µg/mL failed to protect against NRS119 (survival, 1.6%-20%). An in vivo effect of cfr was only detected at concentrations of 30 and 15 µg/mL. In the mouse peritonitis model, LNZ (at doses that mimic human pharmacokinetics) protected mice from challenge with the cfr+ 004-737X strain but was ineffective against the NRS119 strain, which carried 23S rRNA mutations. CONCLUSIONS The fly model offers promising advantages to dissect the in vivo effect of LNZ resistance in S. aureus, and findings from this model appear to be concordant with those from the mouse peritonitis model.
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Affiliation(s)
- Lorena Diaz
- Molecular Genetics and Antimicrobial Resistance Unit, Universidad El Bosque, Bogota, Colombia
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McCusker KP, Medzihradszky KF, Shiver AL, Nichols RJ, Yan F, Maltby DA, Gross CA, Fujimori DG. Covalent intermediate in the catalytic mechanism of the radical S-adenosyl-L-methionine methyl synthase RlmN trapped by mutagenesis. J Am Chem Soc 2012; 134:18074-81. [PMID: 23088750 PMCID: PMC3499099 DOI: 10.1021/ja307855d] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The posttranscriptional modification of ribosomal RNA (rRNA) modulates ribosomal function and confers resistance to antibiotics targeted to the ribosome. The radical S-adenosyl-L-methionine (SAM) methyl synthases, RlmN and Cfr, both methylate A2503 within the peptidyl transferase center of prokaryotic ribosomes, yielding 2-methyl- and 8-methyl-adenosine, respectively. The C2 and C8 positions of adenosine are unusual methylation substrates due to their electrophilicity. To accomplish this reaction, RlmN and Cfr use a shared radical-mediated mechanism. In addition to the radical SAM CX(3)CX(2)C motif, both RlmN and Cfr contain two conserved cysteine residues required for in vivo function, putatively to form (cysteine 355 in RlmN) and resolve (cysteine 118 in RlmN) a covalent intermediate needed to achieve this challenging transformation. Currently, there is no direct evidence for this proposed covalent intermediate. We have further investigated the roles of these conserved cysteines in the mechanism of RlmN. Cysteine 118 mutants of RlmN are unable to resolve the covalent intermediate, either in vivo or in vitro, enabling us to isolate and characterize this intermediate. Additionally, tandem mass spectrometric analyses of mutant RlmN reveal a methylene-linked adenosine modification at cysteine 355. Employing deuterium-labeled SAM and RNA substrates in vitro has allowed us to further clarify the mechanism of formation of this intermediate. Together, these experiments provide compelling evidence for the formation of a covalent intermediate species between RlmN and its rRNA substrate and well as the roles of the conserved cysteine residues in catalysis.
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Affiliation(s)
- Kevin P McCusker
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California 94158, USA
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Le DD, Fujimori DG. Protein and nucleic acid methylating enzymes: mechanisms and regulation. Curr Opin Chem Biol 2012; 16:507-15. [PMID: 23085277 DOI: 10.1016/j.cbpa.2012.09.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 09/17/2012] [Accepted: 09/19/2012] [Indexed: 11/19/2022]
Abstract
Protein and nucleic acid methylating enzymes are implicated in myriad cellular processes. These enzymes utilize diverse chemical mechanisms ranging from nucleophilic substitution-displacement to a novel radical-based reaction found in bacterial iron-sulfur cluster proteins. Within the cell, methylation activity is governed by interactions with endogenous molecular machinery. Of particular interest are the observations that methylating enzyme activity can be allosterically controlled by regulatory binding partners. Recent advances and emerging trends in the study of methylating enzyme mechanisms and regulation highlight the importance of protein and nucleic acid methylation in cellular physiology and disease.
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Affiliation(s)
- Daniel D Le
- Graduate Program in Chemistry and Chemical Biology, University of California, San Francisco, CA 94158, United States
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