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Rahman MA, Heme UH, Parvez MAK. In silico functional annotation of hypothetical proteins from the Bacillus paralicheniformis strain Bac84 reveals proteins with biotechnological potentials and adaptational functions to extreme environments. PLoS One 2022; 17:e0276085. [PMID: 36228026 PMCID: PMC9560612 DOI: 10.1371/journal.pone.0276085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 09/28/2022] [Indexed: 11/26/2022] Open
Abstract
Members of the Bacillus genus are industrial cell factories due to their capacity to secrete significant quantities of biomolecules with industrial applications. The Bacillus paralicheniformis strain Bac84 was isolated from the Red Sea and it shares a close evolutionary relationship with Bacillus licheniformis. However, a significant number of proteins in its genome are annotated as functionally uncharacterized hypothetical proteins. Investigating these proteins' functions may help us better understand how bacteria survive extreme environmental conditions and to find novel targets for biotechnological applications. Therefore, the purpose of our research was to functionally annotate the hypothetical proteins from the genome of B. paralicheniformis strain Bac84. We employed a structured in-silico approach incorporating numerous bioinformatics tools and databases for functional annotation, physicochemical characterization, subcellular localization, protein-protein interactions, and three-dimensional structure determination. Sequences of 414 hypothetical proteins were evaluated and we were able to successfully attribute a function to 37 hypothetical proteins. Moreover, we performed receiver operating characteristic analysis to assess the performance of various tools used in this present study. We identified 12 proteins having significant adaptational roles to unfavorable environments such as sporulation, formation of biofilm, motility, regulation of transcription, etc. Additionally, 8 proteins were predicted with biotechnological potentials such as coenzyme A biosynthesis, phenylalanine biosynthesis, rare-sugars biosynthesis, antibiotic biosynthesis, bioremediation, and others. Evaluation of the performance of the tools showed an accuracy of 98% which represented the rationality of the tools used. This work shows that this annotation strategy will make the functional characterization of unknown proteins easier and can find the target for further investigation. The knowledge of these hypothetical proteins' potential functions aids B. paralicheniformis strain Bac84 in effectively creating a new biotechnological target. In addition, the results may also facilitate a better understanding of the survival mechanisms in harsh environmental conditions.
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Affiliation(s)
- Md. Atikur Rahman
- Institute of Microbiology, Friedrich Schiller University Jena, Thuringia, Germany
| | - Uzma Habiba Heme
- Faculty of Biological Sciences, Friedrich Schiller University Jena, Thuringia, Germany
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Structural basis for plazomicin antibiotic action and resistance. Commun Biol 2021; 4:729. [PMID: 34117352 PMCID: PMC8195987 DOI: 10.1038/s42003-021-02261-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 05/21/2021] [Indexed: 11/22/2022] Open
Abstract
The approval of plazomicin broadened the clinical library of aminoglycosides available for use against emerging bacterial pathogens. Contrarily to other aminoglycosides, resistance to plazomicin is limited; still, instances of resistance have been reported in clinical settings. Here, we present structural insights into the mechanism of plazomicin action and the mechanisms of clinical resistance. The structural data reveal that plazomicin exclusively binds to the 16S ribosomal A site, where it likely interferes with the fidelity of mRNA translation. The unique extensions to the core aminoglycoside scaffold incorporated into the structure of plazomicin do not interfere with ribosome binding, which is analogously seen in the binding of this antibiotic to the AAC(2′)-Ia resistance enzyme. The data provides a structural rationale for resistance conferred by drug acetylation and ribosome methylation, i.e., the two mechanisms of resistance observed clinically. Finally, the crystal structures of plazomicin in complex with both its target and the clinically relevant resistance factor provide a roadmap for next-generation drug development that aims to ameliorate the impact of antibiotic resistance. Golkar, Bassenden et al. report two structures of the latest generation aminoglycoside antibiotic plazomicin in complex with the bacterial 70S ribosome as well as in complex with AAC(2’)-la acetyltransferase, an antibiotic modification enzyme (AME). Their study can be useful in the development of newer aminoglycosides that are not modified by AMEs while being capable of targeting the bacterial ribosome.
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Genau AC, Li Z, Renzaglia KS, Fernandez Pozo N, Nogué F, Haas FB, Wilhelmsson PKI, Ullrich KK, Schreiber M, Meyberg R, Grosche C, Rensing SA. HAG1 and SWI3A/B control of male germ line development in P. patens suggests conservation of epigenetic reproductive control across land plants. PLANT REPRODUCTION 2021; 34:149-173. [PMID: 33839924 PMCID: PMC8128824 DOI: 10.1007/s00497-021-00409-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 04/02/2021] [Indexed: 05/27/2023]
Abstract
KEY MESSAGE Bryophytes as models to study the male germ line: loss-of-function mutants of epigenetic regulators HAG1 and SWI3a/b demonstrate conserved function in sexual reproduction. With the water-to-land transition, land plants evolved a peculiar haplodiplontic life cycle in which both the haploid gametophyte and the diploid sporophyte are multicellular. The switch between these phases was coined alternation of generations. Several key regulators that control the bauplan of either generation are already known. Analyses of such regulators in flowering plants are difficult due to the highly reduced gametophytic generation, and the fact that loss of function of such genes often is embryo lethal in homozygous plants. Here we set out to determine gene function and conservation via studies in bryophytes. Bryophytes are sister to vascular plants and hence allow evolutionary inferences. Moreover, embryo lethal mutants can be grown and vegetatively propagated due to the dominance of the bryophyte gametophytic generation. We determined candidates by selecting single copy orthologs that are involved in transcriptional control, and of which flowering plant mutants show defects during sexual reproduction, with a focus on the under-studied male germ line. We selected two orthologs, SWI3a/b and HAG1, and analyzed loss-of-function mutants in the moss P. patens. In both mutants, due to lack of fertile spermatozoids, fertilization and hence the switch to the diploid generation do not occur. Pphag1 additionally shows arrested male and impaired female gametangia development. We analyzed HAG1 in the dioecious liverwort M. polymorpha and found that in Mphag1 the development of gametangiophores is impaired. Taken together, we find that involvement of both regulators in sexual reproduction is conserved since the earliest divergence of land plants.
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Affiliation(s)
- Anne C Genau
- Plant Cell Biology, Department of Biology, University of Marburg, Marburg, Germany
| | - Zhanghai Li
- Plant Cell Biology, Department of Biology, University of Marburg, Marburg, Germany
| | - Karen S Renzaglia
- Department of Plant Biology, Southern Illinois University, Carbondale, IL, 62901, USA
| | - Noe Fernandez Pozo
- Plant Cell Biology, Department of Biology, University of Marburg, Marburg, Germany
| | - Fabien Nogué
- Institut Jean-Pierre Bourgin, INRAE, Université Paris-Saclay, 78000, Versailles, AgroParisTech, France
| | - Fabian B Haas
- Plant Cell Biology, Department of Biology, University of Marburg, Marburg, Germany
| | - Per K I Wilhelmsson
- Plant Cell Biology, Department of Biology, University of Marburg, Marburg, Germany
| | - Kristian K Ullrich
- Plant Cell Biology, Department of Biology, University of Marburg, Marburg, Germany
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Mona Schreiber
- Plant Cell Biology, Department of Biology, University of Marburg, Marburg, Germany
| | - Rabea Meyberg
- Plant Cell Biology, Department of Biology, University of Marburg, Marburg, Germany
| | - Christopher Grosche
- Plant Cell Biology, Department of Biology, University of Marburg, Marburg, Germany
| | - Stefan A Rensing
- Plant Cell Biology, Department of Biology, University of Marburg, Marburg, Germany.
- BIOSS Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany.
- LOEWE Center for Synthetic Microbiology (SYNMIKRO), Philipps University of Marburg, Marburg, Germany.
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Lin MH, Kuo PC, Chiu YC, Chang YY, Chen SC, Hsu CH. The crystal structure of protein-transporting chaperone BCP1 from Saccharomyces cerevisiae. J Struct Biol 2020; 212:107605. [PMID: 32805410 DOI: 10.1016/j.jsb.2020.107605] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 08/04/2020] [Accepted: 08/12/2020] [Indexed: 11/25/2022]
Abstract
BCP1 is a protein enriched in the nucleus that is required for Mss4 nuclear export and identified as the chaperone of ribosomal protein Rpl23 in Saccharomyces cerevisiae. According to sequence homology, BCP1 is related to the mammalian BRCA2-interacting protein BCCIP and belongs to the BCIP protein family (PF13862) in the Pfam database. However, the BCIP family has no discernible similarity to proteins with known structure. Here, we report the crystal structure of BCP1, presenting an α/β fold in which the central antiparallel β-sheet is flanked by helices. Protein structural classification revealed that BCP1 has similarity to the GNAT superfamily but no conserved substrate-binding residues. Further modeling and protein-protein docking work provide a plausible model to explain the interaction between BCP1 and Rpl23. Our structural analysis presents the first structure of BCIP family and provides a foundation for understanding the molecular basis of BCP1 as a chaperone of Rpl23 for ribosome biosynthesis.
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Affiliation(s)
- Meng-Hsuan Lin
- Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan; Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei 10617, Taiwan
| | - Po-Chih Kuo
- Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Yi-Chih Chiu
- Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei 10617, Taiwan
| | - Yu-Yung Chang
- Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Sheng-Chia Chen
- Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Chun-Hua Hsu
- Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan; Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei 10617, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei 10617, Taiwan.
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Jang H, Kwon S, Jeong CS, Lee CW, Hwang J, Jung KH, Lee JH, Park HH. Structural analysis of a novel substrate-free form of the aminoglycoside 6'-N-acetyltransferase from Enterococcus faecium. Acta Crystallogr F Struct Biol Commun 2020; 76:364-371. [PMID: 32744248 PMCID: PMC7397467 DOI: 10.1107/s2053230x20009735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 07/16/2020] [Indexed: 11/10/2022] Open
Abstract
Aminoglycoside acetyltransferases (AACs) catalyze the transfer of an acetyl group between acetyl-CoA and an aminoglycoside, producing CoA and an acetylated aminoglycoside. AAC(6')-Ii enzymes target the amino group linked to the 6' C atom in an aminoglycoside. Several structures of the AAC(6')-Ii from Enterococcus faecium [Ef-AAC(6')-Ii] have been reported to date. However, the detailed mechanism of its enzymatic function remains elusive. In this study, the crystal structure of Ef-AAC(6')-Ii was determined in a novel substrate-free form. Based on structural analysis, it is proposed that Ef-AAC(6')-Ii sequentially undergoes conformational selection and induced fit for substrate binding. These results therefore provide a novel viewpoint on the mechanism of action of Ef-AAC(6')-Ii.
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Affiliation(s)
- Hyunseok Jang
- College of Pharmacy, Chung-Ang University, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Sunghark Kwon
- College of Pharmacy, Chung-Ang University, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Chang-Sook Jeong
- Unit of Research for Practical Application, Korea Polar Research Institute, Incheon 21990, Republic of Korea
- Department of Polar Sciences, University of Science and Technology, Incheon 21990, Republic of Korea
| | - Chang Woo Lee
- Unit of Research for Practical Application, Korea Polar Research Institute, Incheon 21990, Republic of Korea
| | - Jisub Hwang
- Unit of Research for Practical Application, Korea Polar Research Institute, Incheon 21990, Republic of Korea
- Department of Polar Sciences, University of Science and Technology, Incheon 21990, Republic of Korea
| | - Kyoung Ho Jung
- College of Pharmacy, Chung-Ang University, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Jun Hyuck Lee
- Unit of Research for Practical Application, Korea Polar Research Institute, Incheon 21990, Republic of Korea
- Department of Polar Sciences, University of Science and Technology, Incheon 21990, Republic of Korea
| | - Hyun Ho Park
- College of Pharmacy, Chung-Ang University, Dongjak-gu, Seoul 06974, Republic of Korea
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Sen T, Verma NK. Functional Annotation and Curation of Hypothetical Proteins Present in A Newly Emerged Serotype 1c of Shigella flexneri: Emphasis on Selecting Targets for Virulence and Vaccine Design Studies. Genes (Basel) 2020; 11:genes11030340. [PMID: 32210046 PMCID: PMC7141135 DOI: 10.3390/genes11030340] [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: 02/12/2020] [Revised: 03/18/2020] [Accepted: 03/19/2020] [Indexed: 01/28/2023] Open
Abstract
Shigella flexneri is the principal cause of bacillary dysentery, contributing significantly to the global burden of diarrheal disease. The appearance and increase in the multi-drug resistance among Shigella strains, necessitates further genetic studies and development of improved/new drugs against the pathogen. The presence of an abundance of hypothetical proteins in the genome and how little is known about them, make them interesting genetic targets. The present study aims to carry out characterization of the hypothetical proteins present in the genome of a newly emerged serotype of S. flexneri (strain Y394), toward their novel regulatory functions using various bioinformatics databases/tools. Analysis of the genome sequence rendered 4170 proteins, out of which 721 proteins were annotated as hypothetical proteins (HPs) with no known function. The amino acid sequences of these HPs were evaluated using a combination of latest bioinformatics tools based on homology search against functionally identified proteins. Functional domains were considered as the basis to infer the biological functions of HPs in this case and the annotation helped in assigning various classes to the proteins such as signal transducers, lipoproteins, enzymes, membrane proteins, transporters, virulence, and binding proteins. This study contributes to a better understanding of growth, survival, and disease mechanism at molecular level and provides potential new targets for designing drugs against Shigella infection.
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Comparative Genomic Analysis of Rhodococcus equi: An Insight into Genomic Diversity and Genome Evolution. Int J Genomics 2019; 2019:8987436. [PMID: 31950028 PMCID: PMC6948317 DOI: 10.1155/2019/8987436] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 07/24/2019] [Accepted: 08/11/2019] [Indexed: 12/03/2022] Open
Abstract
Rhodococcus equi, a member of the Rhodococcus genus, is a gram-positive pathogenic bacterium. Rhodococcus possesses an open pan-genome that constitutes the basis of its high genomic diversity and allows for adaptation to specific niche conditions and the changing host environments. Our analysis further showed that the core genome of R. equi contributes to the pathogenicity and niche adaptation of R. equi. Comparative genomic analysis revealed that the genomes of R. equi shared identical collinearity relationship, and heterogeneity was mainly acquired by means of genomic islands and prophages. Moreover, genomic islands in R. equi were always involved in virulence, resistance, or niche adaptation and possibly working with prophages to cause the majority of genome expansion. These findings provide an insight into the genomic diversity, evolution, and structural variation of R. equi and a valuable resource for functional genomic studies.
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Tomar JS, Hosur RV. Polyamine acetylation and substrate-induced oligomeric states in histone acetyltransferase of multiple drug resistant Acinetobacter baumannii. Biochimie 2019; 168:268-276. [PMID: 31786230 DOI: 10.1016/j.biochi.2019.11.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 11/25/2019] [Indexed: 11/16/2022]
Abstract
Histone acetyltransferase (Hpa2) is an unusual acetyltransferase, with a wide range of substrates; including histones, polyamines and aminoglycosides antibiotic. Hpa2 belongs to GNAT superfamily and GNATs are well known for the formation of homo-oligomers. However, the reason behind their oligomerization remained unexplored. Here, oligomeric states of Hpa2 were explored, to understand the functional significance of oligomerization. Biochemical analysis suggests that Hpa2 exists as dimer in solution and self-assembles into tetramer in the spermine, spermidine and kanamycin bound form. Stability analysis with denaturants concludes that homo-oligomerization of Hpa2 relies on bound substrate and not on experimental conditions. Homo-oligomerization in Hpa2 depicts direct correlation with its polyamine acetylating capacity. This correlation and in silico model structures suggest that oligomerization of Hpa2 is associated with the hastening of acetylation process. Interestingly, polyamine acetylation down regulates biofilms formation in E. coli BL21/Hpa2-transformants cells. Therefore, we propose that Hpa2 manipulates survival strategies of the bacterium via polyamines and antibiotics acetylation.
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Affiliation(s)
- Jyoti Singh Tomar
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India.
| | - Ramakrishna Vijayacharya Hosur
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India; UM-DAE Centre for Excellence in Basic Sciences, University Campus Mumbai, India.
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Aminoglycoside antibiotic resistance conferred by Hpa2 of MDR Acinetobacter baumannii: an unusual adaptation of a common histone acetyltransferase. Biochem J 2019; 476:795-808. [PMID: 30573651 DOI: 10.1042/bcj20180791] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 12/18/2018] [Accepted: 12/20/2018] [Indexed: 12/20/2022]
Abstract
Antibiotic-resistant bacteria pose the greatest threat to human health. Among the list of such bacteria released by WHO, carbapenem-resistant Acinetobacter baumannii, for which almost no treatment exists, tops the list. A. baumannii is one of the most troublesome ESKAPE pathogens and mechanisms that have facilitated its rise as a successful pathogen are not well studied. Efforts in this direction have resulted in the identification of Hpa2-Ab, an uncharacterized histone acetyltransferase enzyme of GNAT superfamily. Here, we show that Hpa2-Ab confers resistance against aminoglycoside antibiotics using Escherichia coli DH5α strains in which Hpa2 gene is expressed. Resistivity for aminoglycoside antibiotics is demonstrated with the help of CLSI-2010 and KB tests. Isothermal titration calorimetry, MALDI and acetylation assays indicate that conferred resistance is an outcome of evolved antibiotic acetylation capacity in this. Hpa2 is known to acetylate nuclear molecules; however, here it is found to cross its boundary and participate in other functions. An array of biochemical and biophysical techniques were also used to study this protein, which demonstrates that Hpa2-Ab is intrinsically oligomeric in nature, exists primarily as a dimer and its interface is mainly stabilized by hydrophobic interactions. Our work demonstrates an evolved survival strategy by A. baumannii and provides insights into the mechanism that facilitates it to rise as a successful pathogen.
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Gazi MA, Mahmud S, Fahim SM, Kibria MG, Palit P, Islam MR, Rashid H, Das S, Mahfuz M, Ahmeed T. Functional Prediction of Hypothetical Proteins from Shigella flexneri and Validation of the Predicted Models by Using ROC Curve Analysis. Genomics Inform 2018; 16:e26. [PMID: 30602087 PMCID: PMC6440662 DOI: 10.5808/gi.2018.16.4.e26] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 09/16/2018] [Indexed: 01/04/2023] Open
Abstract
Shigella spp. constitutes some of the key pathogens responsible for the global burden of diarrhoeal disease. With over 164 million reported cases per annum, shigellosis accounts for 1.1 million deaths each year. Majority of these cases occur among the children of the developing nations and the emergence of multi-drug resistance Shigella strains in clinical isolates demands the development of better/new drugs against this pathogen. The genome of Shigella flexneri was extensively analyzed and found 4,362 proteins among which the functions of 674 proteins, termed as hypothetical proteins (HPs) had not been previously elucidated. Amino acid sequences of all these 674 HPs were studied and the functions of a total of 39 HPs have been assigned with high level of confidence. Here we have utilized a combination of the latest versions of databases to assign the precise function of HPs for which no experimental information is available. These HPs were found to belong to various classes of proteins such as enzymes, binding proteins, signal transducers, lipoprotein, transporters, virulence and other proteins. Evaluation of the performance of the various computational tools conducted using receiver operating characteristic curve analysis and a resoundingly high average accuracy of 93.6% were obtained. Our comprehensive analysis will help to gain greater understanding for the development of many novel potential therapeutic interventions to defeat Shigella infection.
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Affiliation(s)
- Md Amran Gazi
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Sultan Mahmud
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Shah Mohammad Fahim
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Mohammad Golam Kibria
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Parag Palit
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Md Rezaul Islam
- International Max Planck Research School, Grisebachstraße 5, 37077 Göttingen, Germany
| | - Humaira Rashid
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Subhasish Das
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Mustafa Mahfuz
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Tahmeed Ahmeed
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
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Jin M, Lu J, Chen Z, Nguyen SH, Mao L, Li J, Yuan Z, Guo J. Antidepressant fluoxetine induces multiple antibiotics resistance in Escherichia coli via ROS-mediated mutagenesis. ENVIRONMENT INTERNATIONAL 2018; 120:421-430. [PMID: 30125859 DOI: 10.1016/j.envint.2018.07.046] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 07/28/2018] [Accepted: 07/29/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Antibiotic resistance poses a great threat to global public health. Overuse of antibiotics is generally considered as the major factor contributing to it. However, little is known about whether non-antibiotic drugs could play potential roles in the emergence of antibiotic resistance. OBJECTIVE We aimed to investigate whether antidepressant fluoxetine induces multiple antibiotic resistances and reveal underlying mechanisms. METHODOLOGY Escherichia coli K12 was exposed to different concentrations of fluoxetine (0, 0.5, 5, 50 and 100 mg/L) and the resistant strains were isolated by plating on antibiotic containing plates. Resistant strains were randomly selected to determine the increase of minimum inhibition concentration (MIC) of multiple antibiotics. Genome-wide DNA sequencing was performed on cells cultured in lysogeny broth (LB) without any fluoxetine or antibiotics exposure. RNA sequencing and proteomic profiling of isolated mutants grown in LB with 100 mg/L fluoxetine were analyzed to reveal the underlying mechanisms. RESULTS Exposure of Escherichia coli to fluoxetine at 5-100 mg/L after repeated subculture in LB for 30 days promoted its mutation frequency resulting in increased resistance against the antibiotics chloramphenicol, amoxicillin and tetracycline. This increase was up to 5.0 × 107 fold in a dose-time pattern. Isolated mutants with resistance to one of these antibiotics also exhibited multiple resistances against fluoroquinolone, aminoglycoside, β-lactams, tetracycline and chloramphenicol. According to global transcriptional and proteomic analyses, the AcrAB-TolC pump together with the YadG/YadH transporter, a Tsx channel and the MdtEF-TolC pump have been triggered to export the antibiotics to the exterior of the cell. Whole-genome DNA analysis of the mutants further revealed that ROS-mediated mutagenesis (e.g., deletion, insertion, and substitution) of DNA-binding transcriptional regulators (e.g., marR, rob, sdiA, cytR and crp) to up-regulate the expression of efflux pumps, may further enhance the antibiotic efflux. CONCLUSIONS Our findings for the first time demonstrated that the exposure to antidepressant fluoxetine induces multiple antibiotic resistance in E. coli via the ROS-mediated mutagenesis.
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Affiliation(s)
- Min Jin
- Advanced Water Management Centre (AWMC), University of Queensland, St Lucia, Brisbane, QLD 4072, Australia; Department of Environment and Health, Tianjin Institute of Environmental & Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin 300050, China
| | - Ji Lu
- Advanced Water Management Centre (AWMC), University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Zhaoyu Chen
- Advanced Water Management Centre (AWMC), University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Son Hoang Nguyen
- Institute for Molecular Bioscience, University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia
| | - Likai Mao
- Advanced Water Management Centre (AWMC), University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Junwen Li
- Department of Environment and Health, Tianjin Institute of Environmental & Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin 300050, China
| | - Zhiguo Yuan
- Advanced Water Management Centre (AWMC), University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Jianhua Guo
- Advanced Water Management Centre (AWMC), University of Queensland, St Lucia, Brisbane, QLD 4072, Australia.
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Amikacin: Uses, Resistance, and Prospects for Inhibition. Molecules 2017; 22:molecules22122267. [PMID: 29257114 PMCID: PMC5889950 DOI: 10.3390/molecules22122267] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 12/13/2017] [Accepted: 12/14/2017] [Indexed: 12/16/2022] Open
Abstract
Aminoglycosides are a group of antibiotics used since the 1940s to primarily treat a broad spectrum of bacterial infections. The primary resistance mechanism against these antibiotics is enzymatic modification by aminoglycoside-modifying enzymes that are divided into acetyl-transferases, phosphotransferases, and nucleotidyltransferases. To overcome this problem, new semisynthetic aminoglycosides were developed in the 70s. The most widely used semisynthetic aminoglycoside is amikacin, which is refractory to most aminoglycoside modifying enzymes. Amikacin was synthesized by acylation with the l-(-)-γ-amino-α-hydroxybutyryl side chain at the C-1 amino group of the deoxystreptamine moiety of kanamycin A. The main amikacin resistance mechanism found in the clinics is acetylation by the aminoglycoside 6'-N-acetyltransferase type Ib [AAC(6')-Ib], an enzyme coded for by a gene found in integrons, transposons, plasmids, and chromosomes of Gram-negative bacteria. Numerous efforts are focused on finding strategies to neutralize the action of AAC(6')-Ib and extend the useful life of amikacin. Small molecules as well as complexes ionophore-Zn+2 or Cu+2 were found to inhibit the acetylation reaction and induced phenotypic conversion to susceptibility in bacteria harboring the aac(6')-Ib gene. A new semisynthetic aminoglycoside, plazomicin, is in advance stage of development and will contribute to renewed interest in this kind of antibiotics.
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Functional assignment for essential hypothetical proteins of Staphylococcus aureus N315. Int J Biol Macromol 2017; 108:765-774. [PMID: 29111265 DOI: 10.1016/j.ijbiomac.2017.10.169] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 09/26/2017] [Accepted: 10/26/2017] [Indexed: 01/05/2023]
Abstract
Staphylococcus aureus, the causative agent of nosocomial infections worldwide, has acquired resistance to almost all antibiotics stressing the need to develop novel drugs against this pathogen. In S. aureus N315, 302 genes have been identified as essential genes, indispensable for growth and survival of the pathogen. The functions of 40 proteins encoded by S. aureus essential genes were found to be hypothetical and thus referred as essential hypothetical proteins (EHPs). The present study aims to carry out functional characterization of EHPs using bioinformatics tools/databases, whose performance was assessed by Receiver operating characteristic curve analysis. Evaluation of physicochemical parameters, homology search against known proteins, domain analysis, subcellular localization analysis and virulence prediction assisted us to characterize EHPs. Functional assignment for 35 EHPs was made with high confidence. They belong to different functional classes like enzymes, binding proteins, miscellaneous proteins, helicases, transporters and virulence factors. Around 35% of EHPs were from hydrolases family. A group of EHPs (32.5%) were predicted as virulence factors. Of 35, 19 essential pathogen-specific proteins were considered as probable drug targets. Two targets were found to be druggable and others were novel targets. Outcome of the study could aid to identify novel drugs for better treatment of S. aureus infections.
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Complementary uses of small angle X-ray scattering and X-ray crystallography. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1623-1630. [PMID: 28743534 DOI: 10.1016/j.bbapap.2017.07.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 07/10/2017] [Accepted: 07/20/2017] [Indexed: 12/11/2022]
Abstract
Most proteins function within networks and, therefore, protein interactions are central to protein function. Although stable macromolecular machines have been extensively studied, dynamic protein interactions remain poorly understood. Small-angle X-ray scattering probes the size, shape and dynamics of proteins in solution at low resolution and can be used to study samples in a large range of molecular weights. Therefore, it has emerged as a powerful technique to study the structure and dynamics of biomolecular systems and bridge fragmented information obtained using high-resolution techniques. Here we review how small-angle X-ray scattering can be combined with other structural biology techniques to study protein dynamics. This article is part of a Special Issue entitled: Biophysics in Canada, edited by Lewis Kay, John Baenziger, Albert Berghuis and Peter Tieleman.
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15
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Distinct Biological Potential of Streptococcus gordonii and Streptococcus sanguinis Revealed by Comparative Genome Analysis. Sci Rep 2017; 7:2949. [PMID: 28592797 PMCID: PMC5462765 DOI: 10.1038/s41598-017-02399-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 04/03/2017] [Indexed: 02/06/2023] Open
Abstract
Streptococcus gordonii and Streptococcus sanguinis are pioneer colonizers of dental plaque and important agents of bacterial infective endocarditis (IE). To gain a greater understanding of these two closely related species, we performed comparative analyses on 14 new S. gordonii and 5 S. sanguinis strains using various bioinformatics approaches. We revealed S. gordonii and S. sanguinis harbor open pan-genomes and share generally high sequence homology and number of core genes including virulence genes. However, we observed subtle differences in genomic islands and prophages between the species. Comparative pathogenomics analysis identified S. sanguinis strains have genes encoding IgA proteases, mitogenic factor deoxyribonucleases, nickel/cobalt uptake and cobalamin biosynthesis. On the contrary, genomic islands of S. gordonii strains contain additional copies of comCDE quorum-sensing system components involved in genetic competence. Two distinct polysaccharide locus architectures were identified, one of which was exclusively present in S. gordonii strains. The first evidence of genes encoding the CylA and CylB system by the α-haemolytic S. gordonii is presented. This study provides new insights into the genetic distinctions between S. gordonii and S. sanguinis, which yields understanding of tooth surfaces colonization and contributions to dental plaque formation, as well as their potential roles in the pathogenesis of IE.
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16
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Aboalroub AA, Bachman AB, Zhang Z, Keramisanou D, Merkler DJ, Gelis I. Acetyl group coordinated progression through the catalytic cycle of an arylalkylamine N-acetyltransferase. PLoS One 2017; 12:e0177270. [PMID: 28486510 PMCID: PMC5423648 DOI: 10.1371/journal.pone.0177270] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 04/25/2017] [Indexed: 11/18/2022] Open
Abstract
The transfer of an acetyl group from acetyl-CoA to an acceptor amine is a ubiquitous biochemical transformation catalyzed by Gcn5-related N-acetyltransferases (GNATs). Although it is established that the reaction proceeds through a sequential ordered mechanism, the role of the acetyl group in driving the ordered formation of binary and ternary complexes remains elusive. Herein, we show that CoA and acetyl-CoA alter the conformation of the substrate binding site of an arylalkylamine N-acetyltransferase (AANAT) to facilitate interaction with acceptor substrates. However, it is the presence of the acetyl group within the catalytic funnel that triggers high affinity binding. Acetyl group occupancy is relayed through a conserved salt bridge between the P-loop and the acceptor binding site, and is manifested as differential dynamics in the CoA and acetyl-CoA-bound states. The capacity of the acetyl group carried by an acceptor to promote its tight binding even in the absence of CoA, but also its mutually exclusive position to the acetyl group of acetyl-CoA underscore its importance in coordinating the progression of the catalytic cycle.
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Affiliation(s)
- Adam A. Aboalroub
- Department of Chemistry, University of South Florida, Tampa, Florida, United States of America
| | - Ashleigh B. Bachman
- Department of Chemistry, University of South Florida, Tampa, Florida, United States of America
| | - Ziming Zhang
- Department of Chemistry, University of South Florida, Tampa, Florida, United States of America
| | - Dimitra Keramisanou
- Department of Chemistry, University of South Florida, Tampa, Florida, United States of America
| | - David J. Merkler
- Department of Chemistry, University of South Florida, Tampa, Florida, United States of America
| | - Ioannis Gelis
- Department of Chemistry, University of South Florida, Tampa, Florida, United States of America
- * E-mail:
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17
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Stogios PJ, Kuhn ML, Evdokimova E, Law M, Courvalin P, Savchenko A. Structural and Biochemical Characterization of Acinetobacter spp. Aminoglycoside Acetyltransferases Highlights Functional and Evolutionary Variation among Antibiotic Resistance Enzymes. ACS Infect Dis 2017; 3:132-143. [PMID: 27785912 DOI: 10.1021/acsinfecdis.6b00058] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Modification of aminoglycosides by N-acetyltransferases (AACs) is one of the major mechanisms of resistance to these antibiotics in human bacterial pathogens. More than 50 enzymes belonging to the AAC(6') subfamily have been identified in Gram-negative and Gram-positive clinical isolates. Our understanding of the molecular function and evolutionary origin of these resistance enzymes remains incomplete. Here we report the structural and enzymatic characterization of AAC(6')-Ig and AAC(6')-Ih from Acinetobacter spp. The crystal structure of AAC(6')-Ig in complex with tobramycin revealed a large substrate-binding cleft remaining partially unoccupied by the substrate, which is in stark contrast with the previously characterized AAC(6')-Ib enzyme. Enzymatic analysis indicated that AAC(6')-Ig and -Ih possess a broad specificity against aminoglycosides but with significantly lower turnover rates as compared to other AAC(6') enzymes. Structure- and function-informed phylogenetic analysis of AAC(6') enzymes led to identification of at least three distinct subfamilies varying in oligomeric state, active site composition, and drug recognition mode. Our data support the concept of AAC(6') functionality originating through convergent evolution from diverse Gcn5-related-N-acetyltransferase (GNAT) ancestral enzymes, with AAC(6')-Ig and -Ih representing enzymes that may still retain ancestral nonresistance functions in the cell as provided by their particular active site properties.
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Affiliation(s)
- Peter J. Stogios
- Department of Chemical
Engineering and Applied Chemistry, University of Toronto, 200 College
Street, Toronto, Ontario M5G 1L6, Canada
| | - Misty L. Kuhn
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, California 94132, United States
| | - Elena Evdokimova
- Department of Chemical
Engineering and Applied Chemistry, University of Toronto, 200 College
Street, Toronto, Ontario M5G 1L6, Canada
| | - Melissa Law
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, California 94132, United States
| | - Patrice Courvalin
- Institut Pasteur, Unité des Agents Antibactériens, 25 rue du Docteur Roux, 75724 Cedex 15 Paris, France
| | - Alexei Savchenko
- Department of Chemical
Engineering and Applied Chemistry, University of Toronto, 200 College
Street, Toronto, Ontario M5G 1L6, Canada
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Holbrook SYL, Garneau-Tsodikova S. Expanding Aminoglycoside Resistance Enzyme Regiospecificity by Mutation and Truncation. Biochemistry 2016; 55:5726-5737. [PMID: 27618454 DOI: 10.1021/acs.biochem.6b00770] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Aminoglycosides (AGs) are broad-spectrum antibiotics famous for their antibacterial activity against Gram-positive and Gram-negative bacteria, as well as mycobacteria. In the United States, the most prescribed AGs, including amikacin (AMK), gentamicin (GEN), and tobramycin (TOB), are vital components of the treatment for resistant bacterial infections. Arbekacin (ABK), a semisynthetic AG, is widely used for the treatment of resistant Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus in Asia. However, the rapid emergence and development of bacterial resistance are limiting the clinical application of AG antibiotics. Of all bacterial resistance mechanisms against AGs, the acquisition of AG-modifying enzymes (AMEs) by bacteria is the most common. It was previously reported that a variant of a bifunctional AME, the 6'-N-AG acetyltransferase-Ie/2″-O-AG phosphotransferase-Ia [AAC(6')-Ie/APH(2″)-Ia], containing a D80G point mutation and a truncation after amino acid 240 modified ABK and AMK at a new position, the 4‴-amine, therefore displaying a change in regiospecificity. In this study, we aimed to verify the altered regiospecificity of this bifunctional enzyme by mutation and truncation for the potential of derivatizing AGs with chemoenzymatic reactions. With the three variant enzymes in this study that contained either mutation only (D80G), truncation only (1-240), or mutation and truncation (D80G-1-240), we characterized their activity by profiling their substrate promiscuity, determined their kinetics parameters, and performed mass spectrometry to determine how and where ABK and AMK were acetylated by these enzymes. We found that the three mutant enzymes possessed distinct acetylation regiospecificity compared to that of the bifunctional AAC(6')-Ie/APH(2″)-Ia enzyme and the functional AAC(6')-Ie domain [AAC(6')/APH(2″)-1-194].
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Affiliation(s)
- Selina Y L Holbrook
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky , Lexington, Kentucky 40536-0596, United States
| | - Sylvie Garneau-Tsodikova
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky , Lexington, Kentucky 40536-0596, United States
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19
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Baettig OM, Shi K, Yachnin BJ, Burk DL, Berghuis AM. Comprehensive characterization of ligand-induced plasticity changes in a dimeric enzyme. FEBS J 2016; 283:3029-38. [PMID: 27333541 PMCID: PMC5053276 DOI: 10.1111/febs.13788] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 05/24/2016] [Accepted: 06/21/2016] [Indexed: 11/30/2022]
Abstract
UNLABELLED An enzyme's inherent structural plasticity is frequently associated with substrate binding, yet detailed structural characterization of flexible proteins remains challenging. This study employs complementary biophysical methods to characterize the partially unfolded structure of substrate-free AAC(6')-Ii, an N-acetyltransferase of the GCN5-related N-acetyltransferase (GNAT) superfamily implicated in conferring broad-spectrum aminoglycoside resistance on Enterococcus faecium. The X-ray crystal structure of AAC(6')-Ii is analyzed to identify relative motions of the structural elements that constitute the dimeric enzyme. Comparison with the previously elucidated crystal structure of AAC(6')-Ii with acetyl coenzyme A (AcCoA) reveals conformational changes that occur upon substrate binding. Our understanding of the enzyme's structural plasticity is further refined with small-angle X-ray scattering and circular dichroism analyses, which together reveal how flexible structural elements impact dimerization and substrate binding. These results clarify the extent of unfolding that AAC(6')-Ii undergoes in the absence of AcCoA and provide a structural connection to previously observed allosteric cooperativity of this enzyme. DATABASE Structural data are available in the PDB database under the accession number 5E96.
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Affiliation(s)
- Oliver M Baettig
- Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, QC, Canada
| | - Kun Shi
- Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, QC, Canada
| | - Brahm J Yachnin
- Department of Chemistry & Chemical Biology, Center for Integrative Proteomics, Rutgers University, Piscataway, NJ, USA
| | - David L Burk
- Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, QC, Canada
| | - Albert M Berghuis
- Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, QC, Canada
- Department of Microbiology and Immunology, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, QC, Canada
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20
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Young BH, Caldwell TA, McKenzie AM, Kokhan O, Berndsen CE. Characterization of the structure and catalytic activity of Legionella pneumophila VipF. Proteins 2016; 84:1422-30. [PMID: 27315603 DOI: 10.1002/prot.25087] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 05/31/2016] [Accepted: 06/13/2016] [Indexed: 11/05/2022]
Abstract
The pathogenic bacteria Legionella pneumophila is known to cause Legionnaires' Disease, a severe pneumonia that can be fatal to immunocompromised individuals and the elderly. Shohdy et al. identified the L. pneumophila vacuole sorting inhibitory protein VipF as a putative N-acetyltransferase based on sequence homology. We have characterized the basic structural and functional properties of VipF to confirm this original functional assignment. Sequence conservation analysis indicates two putative CoA-binding regions within VipF. Homology modeling and small angle X-ray scattering suggest a monomeric, dual-domain structure joined by a flexible linker. Each domain contains the characteristic beta-splay motif found in many acetyltransferases, suggesting that VipF may contain two active sites. Docking experiments suggest reasonable acetyl-CoA binding locations within each beta-splay motif. Broad substrate screening indicated that VipF is capable of acetylating chloramphenicol and both domains are catalytically active. Given that chloramphenicol is not known to be N-acetylated, this is a surprising finding suggesting that VipF is capable of O-acetyltransferase activity. Proteins 2016; 84:1422-1430. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Byron H Young
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
| | - Tracy A Caldwell
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
| | - Aidan M McKenzie
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
| | - Oleksandr Kokhan
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
| | - Christopher E Berndsen
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807.
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21
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Salah Ud-Din AIM, Tikhomirova A, Roujeinikova A. Structure and Functional Diversity of GCN5-Related N-Acetyltransferases (GNAT). Int J Mol Sci 2016; 17:E1018. [PMID: 27367672 PMCID: PMC4964394 DOI: 10.3390/ijms17071018] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 06/14/2016] [Accepted: 06/20/2016] [Indexed: 12/17/2022] Open
Abstract
General control non-repressible 5 (GCN5)-related N-acetyltransferases (GNAT) catalyze the transfer of an acyl moiety from acyl coenzyme A (acyl-CoA) to a diverse group of substrates and are widely distributed in all domains of life. This review of the currently available data acquired on GNAT enzymes by a combination of structural, mutagenesis and kinetic methods summarizes the key similarities and differences between several distinctly different families within the GNAT superfamily, with an emphasis on the mechanistic insights obtained from the analysis of the complexes with substrates or inhibitors. It discusses the structural basis for the common acetyltransferase mechanism, outlines the factors important for the substrate recognition, and describes the mechanism of action of inhibitors of these enzymes. It is anticipated that understanding of the structural basis behind the reaction and substrate specificity of the enzymes from this superfamily can be exploited in the development of novel therapeutics to treat human diseases and combat emerging multidrug-resistant microbial infections.
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Affiliation(s)
- Abu Iftiaf Md Salah Ud-Din
- Infection and Immunity Program, Monash Biomedicine Discovery Institute; Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia.
| | - Alexandra Tikhomirova
- Infection and Immunity Program, Monash Biomedicine Discovery Institute; Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia.
| | - Anna Roujeinikova
- Infection and Immunity Program, Monash Biomedicine Discovery Institute; Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia.
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia.
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22
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Abstract
Allostery is a ubiquitous biological regulatory process in which distant binding sites within a protein or enzyme are functionally and thermodynamically coupled. Allosteric interactions play essential roles in many enzymological mechanisms, often facilitating formation of enzyme-substrate complexes and/or product release. Thus, elucidating the forces that drive allostery is critical to understanding the complex transformations of biomolecules. Currently, a number of models exist to describe allosteric behavior, taking into account energetics as well as conformational rearrangements and fluctuations. In the following Review, we discuss the use of solution NMR techniques designed to probe allosteric mechanisms in enzymes. NMR spectroscopy is unequaled in its ability to detect structural and dynamical changes in biomolecules, and the case studies presented herein demonstrate the range of insights to be gained from this valuable method. We also provide a detailed technical discussion of several specialized NMR experiments that are ideally suited for the study of enzymatic allostery.
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Affiliation(s)
- George P. Lisi
- Department of Chemistry, Yale University, New Haven, CT 06520
| | - J. Patrick Loria
- Department of Chemistry, Yale University, New Haven, CT 06520
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06520
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23
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Favrot L, Blanchard JS, Vergnolle O. Bacterial GCN5-Related N-Acetyltransferases: From Resistance to Regulation. Biochemistry 2016; 55:989-1002. [PMID: 26818562 DOI: 10.1021/acs.biochem.5b01269] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The GCN5-related N-acetyltransferases family (GNAT) is an important family of proteins that includes more than 100000 members among eukaryotes and prokaryotes. Acetylation appears as a major regulatory post-translational modification and is as widespread as phosphorylation. N-Acetyltransferases transfer an acetyl group from acetyl-CoA to a large array of substrates, from small molecules such as aminoglycoside antibiotics to macromolecules. Acetylation of proteins can occur at two different positions, either at the amino-terminal end (αN-acetylation) or at the ε-amino group (εN-acetylation) of an internal lysine residue. GNAT members have been classified into different groups on the basis of their substrate specificity, and in spite of a very low primary sequence identity, GNAT proteins display a common and conserved fold. This Current Topic reviews the different classes of bacterial GNAT proteins, their functions, their structural characteristics, and their mechanism of action.
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Affiliation(s)
- Lorenza Favrot
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - John S Blanchard
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Olivia Vergnolle
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
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24
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de Diego Puente T, Gallego-Jara J, Castaño-Cerezo S, Bernal Sánchez V, Fernández Espín V, García de la Torre J, Manjón Rubio A, Cánovas Díaz M. The Protein Acetyltransferase PatZ from Escherichia coli Is Regulated by Autoacetylation-induced Oligomerization. J Biol Chem 2015; 290:23077-93. [PMID: 26251518 DOI: 10.1074/jbc.m115.649806] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Indexed: 01/31/2023] Open
Abstract
Lysine acetylation is an important post-translational modification in the metabolic regulation of both prokaryotes and eukaryotes. In Escherichia coli, PatZ (formerly YfiQ) is the only known acetyltransferase protein and is responsible for acetyl-CoA synthetase acetylation. In this study, we demonstrated PatZ-positive cooperativity in response to acetyl-CoA and the regulation of acetyl-CoA synthetase activity by the acetylation level. Furthermore, functional analysis of an E809A mutant showed that the conserved glutamate residue is not relevant for the PatZ catalytic mechanism. Biophysical studies demonstrated that PatZ is a stable tetramer in solution and is transformed to its octameric form by autoacetylation. Moreover, this modification is reversed by the sirtuin CobB. Finally, an in silico PatZ tetramerization model based on hydrophobic and electrostatic interactions is proposed and validated by three-dimensional hydrodynamic analysis. These data reveal, for the first time, the structural regulation of an acetyltransferase by autoacetylation in a prokaryotic organism.
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Affiliation(s)
| | - Julia Gallego-Jara
- From the Departments of Biochemistry and Molecular Biology and Immunology (B) and
| | - Sara Castaño-Cerezo
- From the Departments of Biochemistry and Molecular Biology and Immunology (B) and
| | | | - Vanesa Fernández Espín
- Physical Chemistry, Faculty of Chemistry, University of Murcia, Campus of Espinardo, Regional Campus of International Excellence "Campus Mare Nostrum," P. O. Box 4021, Murcia E-30100, Spain
| | - José García de la Torre
- Physical Chemistry, Faculty of Chemistry, University of Murcia, Campus of Espinardo, Regional Campus of International Excellence "Campus Mare Nostrum," P. O. Box 4021, Murcia E-30100, Spain
| | - Arturo Manjón Rubio
- From the Departments of Biochemistry and Molecular Biology and Immunology (B) and
| | - Manuel Cánovas Díaz
- From the Departments of Biochemistry and Molecular Biology and Immunology (B) and
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25
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Freiburger L, Auclair K, Mittermaier A. Global ITC fitting methods in studies of protein allostery. Methods 2015; 76:149-161. [PMID: 25573261 PMCID: PMC5182068 DOI: 10.1016/j.ymeth.2014.12.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/18/2014] [Accepted: 12/19/2014] [Indexed: 10/24/2022] Open
Abstract
Allostery is a nearly ubiquitous feature of biological systems in which ligand binding or covalent modification at one site alters the activities of distant sites in a macromolecule or macromolecular complex. The molecular mechanisms underlying this phenomenon have been studied for decades. Nevertheless there are many aspects that remain poorly understood. ITC yields detailed information on the thermodynamics of biomacromolecular interactions and their coupling to additional equilibria, therefore in principle it is a powerful tool for better understanding how allostery is achieved. A particularly powerful approach involves simultaneously fitting multiple ITC data sets together with those of complementary techniques, especially nuclear magnetic resonance and circular dichroism spectroscopies. In this review, we describe several group-fitting methods for discriminating between different binding models and for improving the accuracy of thermodynamic parameters extracted from variable-temperature ITC data. The techniques were applied to the antibiotic resistance-causing enzyme aminoglycoside-6'-acetyltransferase Ii, uncovering the existence of competition between opposing mechanisms and ligand-dependent switching of the underlying mechanism. These novel observations underline the potential of combining ITC and spectroscopic techniques to study allostery.
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Affiliation(s)
- Lee Freiburger
- Technische Universität München, Chair of Biomolecular NMR Spectroscopy, Germany
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26
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Cox G, Stogios PJ, Savchenko A, Wright GD. Structural and molecular basis for resistance to aminoglycoside antibiotics by the adenylyltransferase ANT(2″)-Ia. mBio 2015; 6:e02180-14. [PMID: 25564464 PMCID: PMC4313920 DOI: 10.1128/mbio.02180-14] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 12/02/2014] [Indexed: 12/21/2022] Open
Abstract
The aminoglycosides are highly effective broad-spectrum antimicrobial agents. However, their efficacy is diminished due to enzyme-mediated covalent modification, which reduces affinity of the drug for the target ribosome. One of the most prevalent aminoglycoside resistance enzymes in Gram-negative pathogens is the adenylyltransferase ANT(2″)-Ia, which confers resistance to gentamicin, tobramycin, and kanamycin. Despite the importance of this enzyme in drug resistance, its structure and molecular mechanism have been elusive. This study describes the structural and mechanistic basis for adenylylation of aminoglycosides by the ANT(2″)-Ia enzyme. ANT(2″)-Ia confers resistance by magnesium-dependent transfer of a nucleoside monophosphate (AMP) to the 2″-hydroxyl of aminoglycoside substrates containing a 2-deoxystreptamine core. The catalyzed reaction follows a direct AMP transfer mechanism from ATP to the substrate antibiotic. Central to catalysis is the coordination of two Mg(2+) ions, positioning of the modifiable substrate ring, and the presence of a catalytic base (Asp86). Comparative structural analysis revealed that ANT(2″)-Ia has a two-domain structure with an N-terminal active-site architecture that is conserved among other antibiotic nucleotidyltransferases, including Lnu(A), LinB, ANT(4')-Ia, ANT(4″)-Ib, and ANT(6)-Ia. There is also similarity between the nucleotidyltransferase fold of ANT(2″)-Ia and DNA polymerase β. This similarity is consistent with evolution from a common ancestor, with the nucleotidyltransferase fold having adapted for activity against chemically distinct molecules. IMPORTANCE : To successfully manage the threat associated with multidrug-resistant infectious diseases, innovative therapeutic strategies need to be developed. One such approach involves the enhancement or potentiation of existing antibiotics against resistant strains of bacteria. The reduction in clinical usefulness of the aminoglycosides is a particular problem among Gram-negative human pathogens, since there are very few therapeutic options for infections caused by these organisms. In order to successfully circumvent or inhibit the activity of aminoglycoside-modifying enzymes, and to thus rejuvenate the activity of the aminoglycoside antibiotics against Gram-negative pathogens, structural and mechanistic information is crucial. This study reveals the structure of a clinically prevalent aminoglycoside resistance enzyme [ANT(2″)-Ia] and depicts the molecular basis underlying modification of antibiotic substrates. Combined, these findings provide the groundwork for the development of broad-spectrum inhibitors against antibiotic nucleotidyltransferases.
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Affiliation(s)
- Georgina Cox
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Peter J Stogios
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada Center for Structural Genomics of Infectious Diseases (CSGID)
| | - Alexei Savchenko
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada Center for Structural Genomics of Infectious Diseases (CSGID)
| | - Gerard D Wright
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
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Smith CA, Toth M, Weiss TM, Frase H, Vakulenko SB. Structure of the bifunctional aminoglycoside-resistance enzyme AAC(6')-Ie-APH(2'')-Ia revealed by crystallographic and small-angle X-ray scattering analysis. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:2754-64. [PMID: 25286858 PMCID: PMC4188014 DOI: 10.1107/s1399004714017635] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 07/31/2014] [Indexed: 11/11/2022]
Abstract
Broad-spectrum resistance to aminoglycoside antibiotics in clinically important Gram-positive staphylococcal and enterococcal pathogens is primarily conferred by the bifunctional enzyme AAC(6')-Ie-APH(2'')-Ia. This enzyme possesses an N-terminal coenzyme A-dependent acetyltransferase domain [AAC(6')-Ie] and a C-terminal GTP-dependent phosphotransferase domain [APH(2'')-Ia], and together they produce resistance to almost all known aminoglycosides in clinical use. Despite considerable effort over the last two or more decades, structural details of AAC(6')-Ie-APH(2'')-Ia have remained elusive. In a recent breakthrough, the structure of the isolated C-terminal APH(2'')-Ia enzyme was determined as the binary Mg2GDP complex. Here, the high-resolution structure of the N-terminal AAC(6')-Ie enzyme is reported as a ternary kanamycin/coenzyme A abortive complex. The structure of the full-length bifunctional enzyme has subsequently been elucidated based upon small-angle X-ray scattering data using the two crystallographic models. The AAC(6')-Ie enzyme is joined to APH(2'')-Ia by a short, predominantly rigid linker at the N-terminal end of a long α-helix. This α-helix is in turn intrinsically associated with the N-terminus of APH(2'')-Ia. This structural arrangement supports earlier observations that the presence of the intact α-helix is essential to the activity of both functionalities of the full-length AAC(6')-Ie-APH(2'')-Ia enzyme.
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Affiliation(s)
- Clyde A. Smith
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, CA 94025, USA
| | - Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Thomas M. Weiss
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, CA 94025, USA
| | - Hilary Frase
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Sergei B. Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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Substrate-dependent switching of the allosteric binding mechanism of a dimeric enzyme. Nat Chem Biol 2014; 10:937-42. [PMID: 25218742 DOI: 10.1038/nchembio.1626] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 07/21/2014] [Indexed: 11/08/2022]
Abstract
Enzyme activity is commonly controlled by allostery, where ligand binding at one site alters the activities of distant sites. Classical explanations for multisubunit proteins involve conformational transitions that are fundamentally deterministic. For example, in the Monod-Wyman-Changeaux (MWC) paradigm, conformational transitions occur simultaneously in all subunits. In the Koshland-Nemethy-Filmer (KNF) paradigm, conformational transitions only occur in ligand-bound subunits. In contrast, recent models predict conformational changes that are governed by probabilities rather than absolute rules. To better understand allostery at the molecular level, we applied a recently developed spectroscopic and calorimetric method to the interactions of a dimeric enzyme with two different ligands. We found that conformational transitions appear MWC-like for a ligand that binds at the dimer interface and KNF-like for a distal ligand. These results provide strong experimental support for probabilistic allosteric theory predictions that an enzyme can exhibit a mixture of MWC and KNF character, with the balance partly governed by subunit interface energies.
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Wu G, Yuan M, Wei L, Zhang Y, Lin Y, Zhang L, Liu Z. Characterization of a novel cold-adapted phosphinothricin N-acetyltransferase from the marine bacterium Rhodococcus sp. strain YM12. ACTA ACUST UNITED AC 2014. [DOI: 10.1016/j.molcatb.2014.03.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Strategies to overcome the action of aminoglycoside-modifying enzymes for treating resistant bacterial infections. Future Med Chem 2014; 5:1285-309. [PMID: 23859208 DOI: 10.4155/fmc.13.80] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Shortly after the discovery of the first antibiotics, bacterial resistance began to emerge. Many mechanisms give rise to resistance; the most prevalent mechanism of resistance to the aminoglycoside (AG) family of antibiotics is the action of aminoglycoside-modifying enzymes (AMEs). Since the identification of these modifying enzymes, many efforts have been put forth to prevent their damaging alterations of AGs. These diverse strategies are discussed within this review, including: creating new AGs that are unaffected by AMEs; developing inhibitors of AMEs to be co-delivered with AGs; or regulating AME expression. Modern high-throughput methods as well as drug combinations and repurposing are highlighted as recent drug-discovery efforts towards fighting the increasing antibiotic resistance crisis.
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Sirigi Reddy AR, Girinathan BP, Zapotocny R, Govind R. Identification and characterization of Clostridium sordellii toxin gene regulator. J Bacteriol 2013; 195:4246-54. [PMID: 23873908 PMCID: PMC3754755 DOI: 10.1128/jb.00711-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 07/12/2013] [Indexed: 02/05/2023] Open
Abstract
Toxigenic Clostridium sordellii causes uncommon but highly lethal infections in humans and animals. Recently, an increased incidence of C. sordellii infections has been reported in women undergoing obstetric interventions. Pathogenic strains of C. sordellii produce numerous virulence factors, including sordellilysin, phospholipase, neuraminidase, and two large clostridial glucosylating toxins, TcsL and TcsH. Recent studies have demonstrated that TcsL toxin is an essential virulence factor for the pathogenicity of C. sordellii. In this study, we identified and characterized TcsR as the toxin gene (tcsL) regulator in C. sordellii. High-throughput sequencing of two C. sordellii strains revealed that tcsR lies within a genomic region that encodes TcsL, TcsH, and TcsE, a putative holin. By using ClosTron technology, we inactivated the tcsR gene in strain ATCC 9714. Toxin production and tcsL transcription were decreased in the tcsR mutant strain. However, the complemented tcsR mutant produced large amounts of toxins, similar to the parental strain. Expression of the Clostridium difficile toxin gene regulator tcdR also restored toxin production to the C. sordellii tcsR mutant, showing that these sigma factors are functionally interchangeable.
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Structural and functional analysis of the yeast N-acetyltransferase Mpr1 involved in oxidative stress tolerance via proline metabolism. Proc Natl Acad Sci U S A 2013; 110:11821-6. [PMID: 23818613 DOI: 10.1073/pnas.1300558110] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mpr1 (sigma1278b gene for proline-analog resistance 1), which was originally isolated as N-acetyltransferase detoxifying the proline analog L-azetidine-2-carboxylate, protects yeast cells from various oxidative stresses. Mpr1 mediates the L-proline and L-arginine metabolism by acetylating L-Δ(1)-pyrroline-5-carboxylate, leading to the L-arginine-dependent production of nitric oxide, which confers oxidative stress tolerance. Mpr1 belongs to the Gcn5-related N-acetyltransferase (GNAT) superfamily, but exhibits poor sequence homology with the GNAT enzymes and unique substrate specificity. Here, we present the X-ray crystal structure of Mpr1 and its complex with the substrate cis-4-hydroxy-L-proline at 1.9 and 2.3 Å resolution, respectively. Mpr1 is folded into α/β-structure with eight-stranded mixed β-sheets and six α-helices. The substrate binds to Asn135 and the backbone amide of Asn172 and Leu173, and the predicted acetyl-CoA-binding site is located near the backbone amide of Phe138 and the side chain of Asn178. Alanine substitution of Asn178, which can interact with the sulfur of acetyl-CoA, caused a large reduction in the apparent kcat value. The replacement of Asn135 led to a remarkable increase in the apparent Km value. These results indicate that Asn178 and Asn135 play an important role in catalysis and substrate recognition, respectively. Such a catalytic mechanism has not been reported in the GNAT proteins. Importantly, the amino acid substitutions in these residues increased the L-Δ(1)-pyrroline-5-carboxylate level in yeast cells exposed to heat stress, indicating that these residues are also crucial for its physiological functions. These studies provide some benefits of Mpr1 applications, such as the breeding of industrial yeasts and the development of antifungal drugs.
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Romanowska J, Reuter N, Trylska J. Comparing aminoglycoside binding sites in bacterial ribosomal RNA and aminoglycoside modifying enzymes. Proteins 2012; 81:63-80. [PMID: 22907688 DOI: 10.1002/prot.24163] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 08/02/2012] [Accepted: 08/09/2012] [Indexed: 11/10/2022]
Abstract
Aminoglycoside antibiotics are used against severe bacterial infections. They bind to the bacterial ribosomal RNA and interfere with the translation process. However, bacteria produce aminoglycoside modifying enzymes (AME) to resist aminoglycoside actions. AMEs form a variable group and yet they specifically recognize and efficiently bind aminoglycosides, which are also diverse in terms of total net charge and the number of pseudo-sugar rings. Here, we present the results of 25 molecular dynamics simulations of three AME representatives and aminoglycoside ribosomal RNA binding site, unliganded and complexed with an aminoglycoside, kanamycin A. A comparison of the aminoglycoside binding sites in these different receptors revealed that the enzymes efficiently mimic the nucleic acid environment of the ribosomal RNA binding cleft. Although internal dynamics of AMEs and their interaction patterns with aminoglycosides differ, the energetical analysis showed that the most favorable sites are virtually the same in the enzymes and RNA. The most copied interactions were of electrostatic nature, but stacking was also replicated in one AME:kanamycin complex. In addition, we found that some water-mediated interactions were very stable in the simulations of the complexes. We show that our simulations reproduce well findings from NMR or X-ray structural studies, as well as results from directed mutagenesis. The outcomes of our analyses provide new insight into aminoglycoside resistance mechanism that is related to the enzymatic modification of these drugs.
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Affiliation(s)
- Julia Romanowska
- Department of Biophysics, Faculty of Physics, University of Warsaw, Hoża 69, 00-681 Warsaw, Poland.
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Cosubstrate tolerance of the aminoglycoside resistance enzyme Eis from Mycobacterium tuberculosis. Antimicrob Agents Chemother 2012; 56:5831-8. [PMID: 22948873 DOI: 10.1128/aac.00932-12] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously demonstrated that aminoglycoside acetyltransferases (AACs) display expanded cosubstrate promiscuity. The enhanced intracellular survival (Eis) protein of Mycobacterium tuberculosis is responsible for the resistance of this pathogen to kanamycin A in a large fraction of clinical isolates. Recently, we discovered that Eis is a unique AAC capable of acetylating multiple amine groups on a large pool of aminoglycoside (AG) antibiotics, an unprecedented property among AAC enzymes. Here, we report a detailed study of the acyl-coenzyme A (CoA) cosubstrate profile of Eis. We show that, in contrast to other AACs, Eis efficiently uses only 3 out of 15 tested acyl-CoA derivatives to modify a variety of AGs. We establish that for almost all acyl-CoAs, the number of sites acylated by Eis is smaller than the number of sites acetylated. We demonstrate that the order of n-propionylation of the AG neamine by Eis is the same as the order of its acetylation. We also show that the 6' position is the first to be n-propionylated on amikacin and netilmicin. By sequential acylation reactions, we show that AGs can be acetylated after the maximum possible n-propionylation of their scaffolds by Eis. The information reported herein will advance our understanding of the multiacetylation mechanism of inactivation of AGs by Eis, which is responsible for M. tuberculosis resistance to some AGs.
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35
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Evolution of insect arylalkylamine N-acetyltransferases: structural evidence from the yellow fever mosquito, Aedes aegypti. Proc Natl Acad Sci U S A 2012; 109:11669-74. [PMID: 22753468 DOI: 10.1073/pnas.1206828109] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Arylalkylamine N-acetyltransferase (aaNAT) catalyzes the transacetylation from acetyl-CoA to arylalkylamines. aaNATs are involved in sclerotization and neurotransmitter inactivation in insects. Phyletic distribution analysis confirms three clusters of aaNAT-like sequences in insects: typical insect aaNAT, polyamine NAT-like aaNAT, and mosquito unique putative aaNAT (paaNAT). Here we studied three proteins: aaNAT2, aaNAT5b, and paaNAT7, each from a different cluster. aaNAT2, a protein from the typical insect aaNAT cluster, uses histamine as a substrate as well as the previously identified arylalkylamines. aaNAT5b, a protein from polyamine NAT -like aaNAT cluster, uses hydrazine and histamine as substrates. The crystal structure of aaNAT2 was determined using single-wavelength anomalous dispersion methods, and that of native aaNAT2, aaNAT5b and paaNAT7 was detected using molecular replacement techniques. All three aaNAT structures have a common fold core of GCN5-related N-acetyltransferase superfamily proteins, along with a unique structural feature: helix/helices between β3 and β4 strands. Our data provide a start toward a more comprehensive understanding of the structure-function relationship and physiology of aaNATs from the mosquito Aedes aegypti and serve as a reference for studying the aaNAT family of proteins from other insect species. The structures of three different types of aaNATs may provide targets for designing insecticides for use in mosquito control.
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Vong K, Auclair K. Understanding and overcoming aminoglycoside resistance caused by N-6'-acetyltransferase. MEDCHEMCOMM 2012; 3:397-407. [PMID: 28018574 PMCID: PMC5179255 DOI: 10.1039/c2md00253a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aminoglycosides occupy a special niche amongst antibiotics in part because of their broad spectrum of action. Bacterial resistance is however menacing to render these drugs obsolete. A significant amount of work has been devoted to understand and overcome aminoglycoside resistance. This mini-review will discuss aminoglycoside-modifying enzymes (AMEs), with a special emphasis on the efforts to comprehend and block resistance caused by aminoglycoside 6'-N-acetyltransferase (AAC(6')).
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Affiliation(s)
- Kenward Vong
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 2K6
| | - Karine Auclair
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 2K6
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37
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Toth M, Vakulenko SB, Smith CA. Purification, crystallization and preliminary X-ray analysis of the aminoglycoside-6'-acetyltransferase AAC(6')-Im. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:472-5. [PMID: 22505423 PMCID: PMC3325823 DOI: 10.1107/s1744309112007117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 02/16/2012] [Indexed: 11/10/2022]
Abstract
Bacterial resistance to the aminoglycoside antibiotics is primarily the result of enzymatic deactivation of the drugs. The aminoglycoside N-acetyltransferases (AACs) are a large family of bacterial enzymes that are responsible for coenzyme-A-facilitated acetylation of aminoglycosides. The gene encoding one of these enzymes, AAC(6')-Im, has been cloned and the protein (comprising 178 amino-acid residues) was expressed in Escherichia coli, purified and crystallized as the kanamycin complex. Synchrotron diffraction data to approximately 2.0 Å resolution were collected from a crystal of this complex on beamline BL12-2 at SSRL (Stanford, California, USA). The crystals belonged to the hexagonal space group P6(5), with approximate unit-cell parameters a = 107.75, c = 37.33 Å, and contained one molecule in the asymmetric unit. Structure determination is under way using molecular replacement.
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Affiliation(s)
- Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Sergei B. Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Clyde A. Smith
- Stanford Synchrotron Radiation Light Source, Stanford University, Menlo Park, CA 94025, USA
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38
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Matesanz R, Diaz JF, Corzana F, Santana AG, Bastida A, Asensio JL. Multiple keys for a single lock: the unusual structural plasticity of the nucleotidyltransferase (4')/kanamycin complex. Chemistry 2012; 18:2875-89. [PMID: 22298309 DOI: 10.1002/chem.201101888] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 12/05/2011] [Indexed: 11/09/2022]
Abstract
The most common mode of bacterial resistance to aminoglycoside antibiotics is the enzyme-catalysed chemical modification of the drug. Over the last two decades, significant efforts in medicinal chemistry have been focused on the design of non- inactivable antibiotics. Unfortunately, this strategy has met with limited success on account of the remarkably wide substrate specificity of aminoglycoside-modifying enzymes. To understand the mechanisms behind substrate promiscuity, we have performed a comprehensive experimental and theoretical analysis of the molecular-recognition processes that lead to antibiotic inactivation by Staphylococcus aureus nucleotidyltransferase 4'(ANT(4')), a clinically relevant protein. According to our results, the ability of this enzyme to inactivate structurally diverse polycationic molecules relies on three specific features of the catalytic region. First, the dominant role of electrostatics in aminoglycoside recognition, in combination with the significant extension of the enzyme anionic regions, confers to the protein/antibiotic complex a highly dynamic character. The motion deduced for the bound antibiotic seem to be essential for the enzyme action and probably provide a mechanism to explore alternative drug inactivation modes. Second, the nucleotide recognition is exclusively mediated by the inorganic fragment. In fact, even inorganic triphosphate can be employed as a substrate. Third, ANT(4') seems to be equipped with a duplicated basic catalyst that is able to promote drug inactivation through different reactive geometries. This particular combination of features explains the enzyme versatility and renders the design of non-inactivable derivatives a challenging task.
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Affiliation(s)
- Ruth Matesanz
- Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
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39
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A novel N-acetylglutamate synthase architecture revealed by the crystal structure of the bifunctional enzyme from Maricaulis maris. PLoS One 2011; 6:e28825. [PMID: 22174908 PMCID: PMC3236213 DOI: 10.1371/journal.pone.0028825] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 11/15/2011] [Indexed: 11/19/2022] Open
Abstract
Novel bifunctional N-acetylglutamate synthase/kinases (NAGS/K) that catalyze the first two steps of arginine biosynthesis and are homologous to vertebrate N-acetylglutamate synthase (NAGS), an essential cofactor-producing enzyme in the urea cycle, were identified in Maricaulis maris and several other bacteria. Arginine is an allosteric inhibitor of NAGS but not NAGK activity. The crystal structure of M. maris NAGS/K (mmNAGS/K) at 2.7 Å resolution indicates that it is a tetramer, in contrast to the hexameric structure of Neisseria gonorrhoeae NAGS. The quaternary structure of crystalline NAGS/K from Xanthomonas campestris (xcNAGS/K) is similar, and cross-linking experiments indicate that both mmNAGS/K and xcNAGS are tetramers in solution. Each subunit has an amino acid kinase (AAK) domain, which is likely responsible for N-acetylglutamate kinase (NAGK) activity and has a putative arginine binding site, and an N-acetyltransferase (NAT) domain that contains the putative NAGS active site. These structures and sequence comparisons suggest that the linker residue 291 may determine whether arginine acts as an allosteric inhibitor or activator in homologous enzymes in microorganisms and vertebrates. In addition, the angle of rotation between AAK and NAT domains varies among crystal forms and subunits within the tetramer. A rotation of 26° is sufficient to close the predicted AcCoA binding site, thus reducing enzymatic activity. Since mmNAGS/K has the highest degree of sequence homology to vertebrate NAGS of NAGS and NAGK enzymes whose structures have been determined, the mmNAGS/K structure was used to develop a structural model of human NAGS that is fully consistent with the functional effects of the 14 missense mutations that were identified in NAGS-deficient patients.
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40
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Szychowski J, Kondo J, Zahr O, Auclair K, Westhof E, Hanessian S, Keillor JW. Inhibition of aminoglycoside-deactivating enzymes APH(3')-IIIa and AAC(6')-Ii by amphiphilic paromomycin O2''-ether analogues. ChemMedChem 2011; 6:1961-6. [PMID: 21905229 DOI: 10.1002/cmdc.201100346] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Indexed: 11/08/2022]
Affiliation(s)
- Janek Szychowski
- Department of Chemistry, Université de Montréal, C. P. 6128, Succ. Centre-Ville, Montréal, QC, H3C 3J7, Canada
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41
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Klimecka MM, Chruszcz M, Font J, Skarina T, Shumilin I, Onopryienko O, Porebski PJ, Cymborowski M, Zimmerman MD, Hasseman J, Glomski IJ, Lebioda L, Savchenko A, Edwards A, Minor W. Structural analysis of a putative aminoglycoside N-acetyltransferase from Bacillus anthracis. J Mol Biol 2011; 410:411-23. [PMID: 21601576 DOI: 10.1016/j.jmb.2011.04.076] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 04/04/2011] [Accepted: 04/29/2011] [Indexed: 11/19/2022]
Abstract
For the last decade, worldwide efforts for the treatment of anthrax infection have focused on developing effective vaccines. Patients that are already infected are still treated traditionally using different types of standard antimicrobial agents. The most popular are antibiotics such as tetracyclines and fluoroquinolones. While aminoglycosides appear to be less effective antimicrobial agents than other antibiotics, synthetic aminoglycosides have been shown to act as potent inhibitors of anthrax lethal factor and may have potential application as antitoxins. Here, we present a structural analysis of the BA2930 protein, a putative aminoglycoside acetyltransferase, which may be a component of the bacterium's aminoglycoside resistance mechanism. The determined structures revealed details of a fold characteristic only for one other protein structure in the Protein Data Bank, namely, YokD from Bacillus subtilis. Both BA2930 and YokD are members of the Antibiotic_NAT superfamily (PF02522). Sequential and structural analyses showed that residues conserved throughout the Antibiotic_NAT superfamily are responsible for the binding of the cofactor acetyl coenzyme A. The interaction of BA2930 with cofactors was characterized by both crystallographic and binding studies.
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Affiliation(s)
- Maria M Klimecka
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
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Effects of altering aminoglycoside structures on bacterial resistance enzyme activities. Antimicrob Agents Chemother 2011; 55:3207-13. [PMID: 21537023 DOI: 10.1128/aac.00312-11] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aminoglycoside-modifying enzymes (AMEs) constitute the most prevalent mechanism of resistance to aminoglycosides by bacteria. We show that aminoglycosides can be doubly modified by the sequential actions of AMEs, with the activity of the second AME in most cases unaffected, decreased, or completely abolished. We demonstrate that the bifunctional enzyme AAC(3)-Ib/AAC(6')-Ib' can diacetylate gentamicin. Since single acetylation does not always inactivate the parent drugs completely, two modifications likely provide more-robust inactivation in vivo.
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43
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Yan X, Akinnusi TO, Larsen AT, Auclair K. Synthesis of 4'-aminopantetheine and derivatives to probe aminoglycoside N-6'-acetyltransferase. Org Biomol Chem 2011; 9:1538-46. [PMID: 21225062 PMCID: PMC3084192 DOI: 10.1039/c0ob01018a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A convenient synthesis of 4'-aminopantetheine from commercial D-pantethine is reported. The amino group was introduced by reductive amination in order to avoid substitution at a sterically congested position. Derivatives of 4'-aminopantetheine were also prepared to evaluate the effect of O-to-N substitution on inhibitors of the resistance-causing enzyme aminoglycoside N-6'-acetyltransferase. The biological results combined with docking studies indicate that in spite of its reported unusual flexibility and ability to adopt different folds, this enzyme is highly specific for AcCoA.
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Affiliation(s)
- Xuxu Yan
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 2K6
| | - T. Olukayode Akinnusi
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 2K6
| | - Aaron T. Larsen
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 2K6
| | - Karine Auclair
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 2K6
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44
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Competing allosteric mechanisms modulate substrate binding in a dimeric enzyme. Nat Struct Mol Biol 2011; 18:288-94. [PMID: 21278754 DOI: 10.1038/nsmb.1978] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Accepted: 11/16/2010] [Indexed: 11/08/2022]
Abstract
Allostery has been studied for many decades, yet it remains challenging to determine experimentally how it occurs at a molecular level. We have developed an approach combining isothermal titration calorimetry, circular dichroism and nuclear magnetic resonance spectroscopy to quantify allostery in terms of protein thermodynamics, structure and dynamics. This strategy was applied to study the interaction between aminoglycoside N-(6')-acetyltransferase-Ii and one of its substrates, acetyl coenzyme A. It was found that homotropic allostery between the two active sites of the homodimeric enzyme is modulated by opposing mechanisms. One follows a classical Koshland-Némethy-Filmer (KNF) paradigm, whereas the other follows a recently proposed mechanism in which partial unfolding of the subunits is coupled to ligand binding. Competition between folding, binding and conformational changes represents a new way to govern energetic communication between binding sites.
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45
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Affiliation(s)
- Mariya Morar
- M.G. DeGroote Institute for Infectious Disease Research and the Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, L8N 3Z5, Canada;
| | - Gerard D. Wright
- M.G. DeGroote Institute for Infectious Disease Research and the Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, L8N 3Z5, Canada;
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46
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Abstract
Aminoglycosides have been an essential component of the armamentarium in the treatment of life-threatening infections. Unfortunately, their efficacy has been reduced by the surge and dissemination of resistance. In some cases the levels of resistance reached the point that rendered them virtually useless. Among many known mechanisms of resistance to aminoglycosides, enzymatic modification is the most prevalent in the clinical setting. Aminoglycoside modifying enzymes catalyze the modification at different -OH or -NH₂ groups of the 2-deoxystreptamine nucleus or the sugar moieties and can be nucleotidyltransferases, phosphotransferases, or acetyltransferases. The number of aminoglycoside modifying enzymes identified to date as well as the genetic environments where the coding genes are located is impressive and there is virtually no bacteria that is unable to support enzymatic resistance to aminoglycosides. Aside from the development of new aminoglycosides refractory to as many as possible modifying enzymes there are currently two main strategies being pursued to overcome the action of aminoglycoside modifying enzymes. Their successful development would extend the useful life of existing antibiotics that have proven effective in the treatment of infections. These strategies consist of the development of inhibitors of the enzymatic action or of the expression of the modifying enzymes.
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Houghton JL, Green KD, Chen W, Garneau-Tsodikova S. The future of aminoglycosides: the end or renaissance? Chembiochem 2010; 11:880-902. [PMID: 20397253 DOI: 10.1002/cbic.200900779] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Indexed: 11/05/2022]
Abstract
Although aminoglycosides have been used as antibacterials for decades, their use has been hindered by their inherent toxicity and the resistance that has emerged to these compounds. It seems that such issues have relegated a formerly front-line class of antimicrobials to the proverbial back shelf. However, recent advances have demonstrated that novel aminoglycosides have a potential to overcome resistance as well as to be used to treat HIV-1 and even human genetic disorders, with abrogated toxicity. It is not the end for aminoglycosides, but rather, the challenges faced by researchers have led to ingenuity and a change in how we view this class of compounds, a renaissance.
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Affiliation(s)
- Jacob L Houghton
- Department of Medicinal Chemistry in the College of Pharmacy, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA
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Bandyopadhyay D, Huan J, Prins J, Snoeyink J, Wang W, Tropsha A. Identification of family-specific residue packing motifs and their use for structure-based protein function prediction: II. Case studies and applications. J Comput Aided Mol Des 2009; 23:785-97. [PMID: 19548090 DOI: 10.1007/s10822-009-9277-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Accepted: 04/22/2009] [Indexed: 11/25/2022]
Abstract
This paper describes several case studies concerning protein function inference from its structure using our novel approach described in the accompanying paper. This approach employs family-specific motifs, i.e. three-dimensional amino acid packing patterns that are statistically prevalent within a protein family. For our case studies we have selected families from the SCOP and EC classifications and analyzed the discriminating power of the motifs in depth. We have devised several benchmarks to compare motifs mined from unweighted topological graph representations of protein structures with those from distance-labeled (weighted) representations, demonstrating the superiority of the latter for function inference in most families. We have tested the robustness of our motif library by inferring the function of new members added to SCOP families, and discriminating between several families that are structurally similar but functionally divergent. Furthermore we have applied our method to predict function for several proteins characterized in structural genomics projects, including orphan structures, and we discuss several selected predictions in depth. Some of our predictions have been corroborated by other computational methods, and some have been validated by independent experimental studies, validating our approach for protein function inference from structure.
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AAC(6')-Iaf, a novel aminoglycoside 6'-N-acetyltransferase from multidrug-resistant Pseudomonas aeruginosa clinical isolates. Antimicrob Agents Chemother 2009; 53:2327-34. [PMID: 19349516 DOI: 10.1128/aac.01360-08] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report here the characterization of a novel aminoglycoside resistance gene, aac(6')-Iaf, present in two multidrug-resistant (MDR) Pseudomonas aeruginosa clinical isolates. These isolates, IMCJ798 and IMCJ799, were independently obtained from two patients, one with a urinary tract infection and the other with a decubitus ulcer, in a hospital located in the western part of Japan. Although the antibiotic resistance profiles of IMCJ798 and IMCJ799 were similar to that of MDR P. aeruginosa IMCJ2.S1, which caused outbreaks in the eastern part of Japan, the pulsed-field gel electrophoresis patterns for these isolates were different from that for IMCJ2.S1. Both IMCJ798 and IMCJ799 were found to contain a novel chromosomal class 1 integron, In123, which included aac(6')-Iaf as the first cassette gene. The encoded protein, AAC(6')-Iaf, was found to consist of 183 amino acids, with 91 and 87% identity to AAC(6')-Iq and AAC(6')-Im, respectively. IMCJ798, IMCJ799, and Escherichia coli transformants carrying a plasmid containing the aac(6')-Iaf gene and its upstream region were highly resistant to amikacin, dibekacin, and kanamycin but not to gentamicin. The production of AAC(6')-Iaf in these strains was confirmed by Western blot analysis. Thin-layer chromatography indicated that AAC(6')-Iaf is a functional acetyltransferase that specifically modifies the amino groups at the 6' positions of aminoglycosides. Collectively, these findings indicate that AAC(6')-Iaf contributes to aminoglycoside resistance.
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Gao F, Yan X, Auclair K. Synthesis of a phosphonate-linked aminoglycoside-coenzyme a bisubstrate and use in mechanistic studies of an enzyme involved in aminoglycoside resistance. Chemistry 2009; 15:2064-70. [PMID: 19152351 DOI: 10.1002/chem.200802172] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Just five steps! The synthesis of a phosphonate-linked aminoglycoside-coenzyme A derivative (see scheme) that includes a Michael addition in water has been realized in just five steps. Aminoglycoside N-6'-acetyltransferases (AAC(6')s) are important determinants of antibiotic resistance. A good mechanistic understanding of these enzymes is essential to overcome aminoglycoside resistance. We have previously reported the synthesis of amide- and sulfonamide-linked aminoglycoside-coenzyme A conjugates, which were useful mechanistic and structural probes of AAC(6')s. We report here the synthesis of a phosphonate-linked aminoglycoside-coenzyme A variant, which is expected to be a superior mimic of the tetrahedral intermediate proposed for catalysis by AAC(6')s. This synthetic target is especially challenging for a number of reasons, including the presence of multiple functional groups, the water solubility of both starting materials, and incompatibility of P(III) chemistry with water. We have overcome these challenges by adding the expensive coenzyme A in the last step by means of an elegant Michael-type addition onto a vinylphosphonate in water. Overall, a single protection step was needed. The decreased inhibitory potency of this bisubstrate compared to that of the amide-linked analogue suggests that Enterococcus faecium AAC(6')-Ii may not stabilize the proposed tetrahedral intermediate, and may act mainly through proximity catalysis.
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Affiliation(s)
- Feng Gao
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada
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