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Lewis AM, Fallon T, Dittemore GA, Sheppard K. Evolution and variation in amide aminoacyl-tRNA synthesis. IUBMB Life 2024. [PMID: 38391119 DOI: 10.1002/iub.2811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 01/22/2024] [Indexed: 02/24/2024]
Abstract
The amide proteogenic amino acids, asparagine and glutamine, are two of the twenty amino acids used in translation by all known life. The aminoacyl-tRNA synthetases for asparagine and glutamine, asparaginyl-tRNA synthetase and glutaminyl tRNA synthetase, evolved after the split in the last universal common ancestor of modern organisms. Before that split, life used two-step indirect pathways to synthesize asparagine and glutamine on their cognate tRNAs to form the aminoacyl-tRNA used in translation. These two-step pathways were retained throughout much of the bacterial and archaeal domains of life and eukaryotic organelles. The indirect routes use non-discriminating aminoacyl-tRNA synthetases (non-discriminating aspartyl-tRNA synthetase and non-discriminating glutamyl-tRNA synthetase) to misaminoacylate the tRNA. The misaminoacylated tRNA formed is then transamidated into the amide aminoacyl-tRNA used in protein synthesis by tRNA-dependent amidotransferases (GatCAB and GatDE). The enzymes and tRNAs involved assemble into complexes known as transamidosomes to help maintain translational fidelity. These pathways have evolved to meet the varied cellular needs across a diverse set of organisms, leading to significant variation. In certain bacteria, the indirect pathways may provide a means to adapt to cellular stress by reducing the fidelity of protein synthesis. The retention of these indirect pathways versus acquisition of asparaginyl-tRNA synthetase and glutaminyl tRNA synthetase in lineages likely involves a complex interplay of the competing uses of glutamine and asparagine beyond translation, energetic costs, co-evolution between enzymes and tRNA, and involvement in stress response that await further investigation.
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Affiliation(s)
- Alexander M Lewis
- Chemistry Department, Skidmore College, Saratoga Springs, New York, USA
| | - Trevor Fallon
- Chemistry Department, Skidmore College, Saratoga Springs, New York, USA
| | | | - Kelly Sheppard
- Chemistry Department, Skidmore College, Saratoga Springs, New York, USA
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2
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An Amidase Gene, ipaH, Is Responsible for the Initial Step in the Iprodione Degradation Pathway of Paenarthrobacter sp. Strain YJN-5. Appl Environ Microbiol 2018; 84:AEM.01150-18. [PMID: 30054359 DOI: 10.1128/aem.01150-18] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Accepted: 07/20/2018] [Indexed: 11/20/2022] Open
Abstract
Iprodione [3-(3,5-dichlorophenyl) N-isopropyl-2,4-dioxoimidazolidine-1-carboxamide] is a highly effective broad-spectrum dicarboxamide fungicide. Several bacteria with iprodione-degrading capabilities have been reported; however, the enzymes and genes involved in this process have not been characterized. In this study, an iprodione-degrading strain, Paenarthrobacter sp. strain YJN-5, was isolated and characterized. Strain YJN-5 degraded iprodione through the typical pathway, with hydrolysis of its N-1 amide bond to N-(3,5-dichlorophenyl)-2,4-dioxoimidazolidine as the initial step. The ipaH gene, encoding a novel amidase responsible for this step, was cloned from strain YJN-5 by the shotgun method. IpaH shares the highest similarity (40%) with an indoleacetamide hydrolase (IAHH) from Bradyrhizobium diazoefficiens USDA 110. IpaH displayed maximal enzymatic activity at 35°C and pH 7.5, and it was not a metalloamidase. The kcat and Km of IpaH against iprodione were 22.42 s-1 and 7.33 μM, respectively, and the catalytic efficiency value (kcat/Km ) was 3.09 μM-1 s-1 IpaH has a Ser-Ser-Lys motif, which is conserved among members of the amidase signature family. The replacement of Lys82, Ser157, and Ser181 with alanine in IpaH led to the complete loss of enzymatic activity. Furthermore, strain YJN-5M lost the ability to degrade iprodione, suggesting that ipaH is the only gene responsible for the initial iprodione degradation step. The ipaH gene could also be amplified from another previously reported iprodione-degrading strain, Microbacterium sp. strain YJN-G. The sequence similarity between the two IpaHs at the amino acid level was 98%, indicating that conservation of IpaH exists in different strains.IMPORTANCE Iprodione is a widely used dicarboxamide fungicide, and its residue has been frequently detected in the environment. The U.S. Environmental Protection Agency has classified iprodione as moderately toxic to small animals and a probable carcinogen to humans. Bacterial degradation of iprodione has been widely investigated. Previous studies demonstrate that hydrolysis of its N-1 amide bond is the initial step in the typical bacterial degradation pathway of iprodione; however, enzymes or genes involved in iprodione degradation have yet to be reported. In this study, a novel ipaH gene encoding an amidase responsible for the initial degradation step of iprodione in Paenarthrobacter sp. strain YJN-5 was cloned. In addition, the characteristics and key amino acid sites of IpaH were investigated. These findings enhance our understanding of the microbial degradation mechanism of iprodione.
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Nair N, Raff H, Islam MT, Feen M, Garofalo DM, Sheppard K. The Bacillus subtilis and Bacillus halodurans Aspartyl-tRNA Synthetases Retain Recognition of tRNA(Asn). J Mol Biol 2016; 428:618-630. [PMID: 26804570 DOI: 10.1016/j.jmb.2016.01.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 01/13/2016] [Accepted: 01/13/2016] [Indexed: 12/19/2022]
Abstract
Synthesis of asparaginyl-tRNA (Asn-tRNA(Asn)) in bacteria can be formed either by directly ligating Asn to tRNA(Asn) using an asparaginyl-tRNA synthetase (AsnRS) or by synthesizing Asn on the tRNA. In the latter two-step indirect pathway, a non-discriminating aspartyl-tRNA synthetase (ND-AspRS) attaches Asp to tRNA(Asn) and the amidotransferase GatCAB transamidates the Asp to Asn on the tRNA. GatCAB can be similarly used for Gln-tRNA(Gln) formation. Most bacteria are predicted to use only one route for Asn-tRNA(Asn) formation. Given that Bacillus halodurans and Bacillus subtilis encode AsnRS for Asn-tRNA(Asn) formation and Asn synthetases to synthesize Asn and GatCAB for Gln-tRNA(Gln) synthesis, their AspRS enzymes were thought to be specific for tRNA(Asp). However, we demonstrate that the AspRSs are non-discriminating and can be used with GatCAB to synthesize Asn. The results explain why B. subtilis with its Asn synthetase genes knocked out is still an Asn prototroph. Our phylogenetic analysis suggests that this may be common among Firmicutes and 30% of all bacteria. In addition, the phylogeny revealed that discrimination toward tRNA(Asp) by AspRS has evolved independently multiple times. The retention of the indirect pathway in B. subtilis and B. halodurans likely reflects the ancient link between Asn biosynthesis and its use in translation that enabled Asn to be added to the genetic code.
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Affiliation(s)
- Nilendra Nair
- Chemistry Department, Skidmore College, Saratoga Springs, NY 12866, USA
| | - Hannah Raff
- Chemistry Department, Skidmore College, Saratoga Springs, NY 12866, USA
| | | | - Melanie Feen
- Chemistry Department, Skidmore College, Saratoga Springs, NY 12866, USA
| | - Denise M Garofalo
- Chemistry Department, Skidmore College, Saratoga Springs, NY 12866, USA
| | - Kelly Sheppard
- Chemistry Department, Skidmore College, Saratoga Springs, NY 12866, USA.
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4
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Mailu BM, Li L, Arthur J, Nelson TM, Ramasamy G, Fritz-Wolf K, Becker K, Gardner MJ. Plasmodium Apicoplast Gln-tRNAGln Biosynthesis Utilizes a Unique GatAB Amidotransferase Essential for Erythrocytic Stage Parasites. J Biol Chem 2015; 290:29629-41. [PMID: 26318454 DOI: 10.1074/jbc.m115.655100] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Indexed: 01/25/2023] Open
Abstract
The malaria parasite Plasmodium falciparum apicoplast indirect aminoacylation pathway utilizes a non-discriminating glutamyl-tRNA synthetase to synthesize Glu-tRNA(Gln) and a glutaminyl-tRNA amidotransferase to convert Glu-tRNA(Gln) to Gln-tRNA(Gln). Here, we show that Plasmodium falciparum and other apicomplexans possess a unique heterodimeric glutamyl-tRNA amidotransferase consisting of GatA and GatB subunits (GatAB). We localized the P. falciparum GatA and GatB subunits to the apicoplast in blood stage parasites and demonstrated that recombinant GatAB converts Glu-tRNA(Gln) to Gln-tRNA(Gln) in vitro. We demonstrate that the apicoplast GatAB-catalyzed reaction is essential to the parasite blood stages because we could not delete the Plasmodium berghei gene encoding GatA in blood stage parasites in vivo. A phylogenetic analysis placed the split between Plasmodium GatB, archaeal GatE, and bacterial GatB prior to the phylogenetic divide between bacteria and archaea. Moreover, Plasmodium GatA also appears to have emerged prior to the bacterial-archaeal phylogenetic divide. Thus, although GatAB is found in Plasmodium, it emerged prior to the phylogenetic separation of archaea and bacteria.
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Affiliation(s)
- Boniface M Mailu
- From the Center for Infectious Disease Research, Seattle, Washington 98109
| | - Ling Li
- From the Center for Infectious Disease Research, Seattle, Washington 98109
| | - Jen Arthur
- From the Center for Infectious Disease Research, Seattle, Washington 98109
| | - Todd M Nelson
- From the Center for Infectious Disease Research, Seattle, Washington 98109
| | - Gowthaman Ramasamy
- From the Center for Infectious Disease Research, Seattle, Washington 98109
| | - Karin Fritz-Wolf
- the Department of Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Giessen 35392 Germany, and the Max-Planck Institute for Medical Research, Jahnstrasse 29, D-69120 Heidelberg, Germany
| | - Katja Becker
- the Department of Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Giessen 35392 Germany, and
| | - Malcolm J Gardner
- From the Center for Infectious Disease Research, Seattle, Washington 98109, the Department of Global Health, University of Washington, Seattle, Washington 98195,
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5
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Shepherd J, Ibba M. Bacterial transfer RNAs. FEMS Microbiol Rev 2015; 39:280-300. [PMID: 25796611 DOI: 10.1093/femsre/fuv004] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/21/2015] [Indexed: 11/14/2022] Open
Abstract
Transfer RNA is an essential adapter molecule that is found across all three domains of life. The primary role of transfer RNA resides in its critical involvement in the accurate translation of messenger RNA codons during protein synthesis and, therefore, ultimately in the determination of cellular gene expression. This review aims to bring together the results of intensive investigations into the synthesis, maturation, modification, aminoacylation, editing and recycling of bacterial transfer RNAs. Codon recognition at the ribosome as well as the ever-increasing number of alternative roles for transfer RNA outside of translation will be discussed in the specific context of bacterial cells.
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Affiliation(s)
- Jennifer Shepherd
- Department of Microbiology and the Center for RNA Biology, Ohio State University, Columbus, Ohio 43210, USA
| | - Michael Ibba
- Department of Microbiology and the Center for RNA Biology, Ohio State University, Columbus, Ohio 43210, USA
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Hydrazidase, a novel amidase signature enzyme that hydrolyzes acylhydrazides. J Bacteriol 2015; 197:1115-24. [PMID: 25583978 DOI: 10.1128/jb.02443-14] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The degradation mechanisms of natural and artificial hydrazides have been elucidated. Here we screened and isolated bacteria that utilize the acylhydrazide 4-hydroxybenzoic acid 1-phenylethylidene hydrazide (HBPH) from soils. Physiological and phylogenetic studies identified one bacterium as Microbacterium sp. strain HM58-2, from which we purified intracellular hydrazidase, cloned its gene, and prepared recombinant hydrazidase using an Escherichia coli expression system. The Microbacterium sp. HM58-2 hydrazidase is a 631-amino-acid monomer that was 31% identical to indoleacetamide hydrolase isolated from Bradyrhizobium japonicum. Phylogenetic studies indicated that the Microbacterium sp. HM58-2 hydrazidase constitutes a novel hydrazidase group among amidase signature proteins that are distributed within proteobacteria, actinobacteria, and firmicutes. The hydrazidase stoichiometrically hydrolyzed the acylhydrazide residue of HBPH to the corresponding acid and hydrazine derivative. Steady-state kinetics showed that the enzyme hydrolyzes structurally related 4-hydrozybenzamide to hydroxybenzoic acid at a lower rate than HBPH, indicating that the hydrazidase prefers hydrazide to amide. The hydrazidase contains the catalytic Ser-Ser-Lys motif that is conserved among members of the amidase signature family; it shares a catalytic mechanism with amidases, according to mutagenesis findings, and another hydrazidase-specific mechanism must exist that compensates for the absence of the catalytic Ser residue. The finding that an environmental bacterium produces hydrazidase implies the existence of a novel bacterial mechanism of hydrazide degradation that impacts its ecological role.
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Structure of the Pseudomonas aeruginosa transamidosome reveals unique aspects of bacterial tRNA-dependent asparagine biosynthesis. Proc Natl Acad Sci U S A 2014; 112:382-7. [PMID: 25548166 DOI: 10.1073/pnas.1423314112] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many prokaryotes lack a tRNA synthetase to attach asparagine to its cognate tRNA(Asn), and instead synthesize asparagine from tRNA(Asn)-bound aspartate. This conversion involves two enzymes: a nondiscriminating aspartyl-tRNA synthetase (ND-AspRS) that forms Asp-tRNA(Asn), and a heterotrimeric amidotransferase GatCAB that amidates Asp-tRNA(Asn) to form Asn-tRNA(Asn) for use in protein synthesis. ND-AspRS, GatCAB, and tRNA(Asn) may assemble in an ∼400-kDa complex, known as the Asn-transamidosome, which couples the two steps of asparagine biosynthesis in space and time to yield Asn-tRNA(Asn). We report the 3.7-Å resolution crystal structure of the Pseudomonas aeruginosa Asn-transamidosome, which represents the most common machinery for asparagine biosynthesis in bacteria. We show that, in contrast to a previously described archaeal-type transamidosome, a bacteria-specific GAD domain of ND-AspRS provokes a principally new architecture of the complex. Both tRNA(Asn) molecules in the transamidosome simultaneously serve as substrates and scaffolds for the complex assembly. This architecture rationalizes an elevated dynamic and a greater turnover of ND-AspRS within bacterial-type transamidosomes, and possibly may explain a different evolutionary pathway of GatCAB in organisms with bacterial-type vs. archaeal-type Asn-transamidosomes. Importantly, because the two-step pathway for Asn-tRNA(Asn) formation evolutionarily preceded the direct attachment of Asn to tRNA(Asn), our structure also may reflect the mechanism by which asparagine was initially added to the genetic code.
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8
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Alperstein A, Ulrich B, Garofalo DM, Dreisbach R, Raff H, Sheppard K. The predatory bacterium Bdellovibrio bacteriovorus aspartyl-tRNA synthetase recognizes tRNAAsn as a substrate. PLoS One 2014; 9:e110842. [PMID: 25338061 PMCID: PMC4206432 DOI: 10.1371/journal.pone.0110842] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 09/20/2014] [Indexed: 11/29/2022] Open
Abstract
The predatory bacterium Bdellovibrio bacteriovorus preys on other Gram-negative bacteria and was predicted to be an asparagine auxotroph. However, despite encoding asparaginyl-tRNA synthetase and glutaminyl-tRNA synthetase, B. bacteriovorus also contains the amidotransferase GatCAB. Deinococcus radiodurans, and Thermus thermophilus also encode both of these aminoacyl-tRNA synthetases with GatCAB. Both also code for a second aspartyl-tRNA synthetase and use the additional aspartyl-tRNA synthetase with GatCAB to synthesize asparagine on tRNAAsn. Unlike those two bacteria, B. bacteriovorus encodes only one aspartyl-tRNA synthetase. Here we demonstrate the lone B. bacteriovorus aspartyl-tRNA synthetase catalyzes aspartyl-tRNAAsn formation that GatCAB can then amidate to asparaginyl-tRNAAsn. This non-discriminating aspartyl-tRNA synthetase with GatCAB thus provides B. bacteriovorus a second route for Asn-tRNAAsn formation with the asparagine synthesized in a tRNA-dependent manner. Thus, in contrast to a previous prediction, B. bacteriovorus codes for a biosynthetic route for asparagine. Analysis of bacterial genomes suggests a significant number of other bacteria may also code for both routes for Asn-tRNAAsn synthesis with only a limited number encoding a second aspartyl-tRNA synthetase.
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Affiliation(s)
- Ariel Alperstein
- Chemistry Department, Skidmore College, Saratoga Springs, New York, United States of America
| | - Brittany Ulrich
- Chemistry Department, Skidmore College, Saratoga Springs, New York, United States of America
| | - Denise M. Garofalo
- Chemistry Department, Skidmore College, Saratoga Springs, New York, United States of America
| | - Ruth Dreisbach
- Chemistry Department, Skidmore College, Saratoga Springs, New York, United States of America
| | - Hannah Raff
- Chemistry Department, Skidmore College, Saratoga Springs, New York, United States of America
| | - Kelly Sheppard
- Chemistry Department, Skidmore College, Saratoga Springs, New York, United States of America
- * E-mail:
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9
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Mladenova SR, Stein KR, Bartlett L, Sheppard K. Relaxed tRNA specificity of theStaphylococcus aureusaspartyl-tRNA synthetase enables RNA-dependent asparagine biosynthesis. FEBS Lett 2014; 588:1808-12. [DOI: 10.1016/j.febslet.2014.03.042] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 03/17/2014] [Accepted: 03/18/2014] [Indexed: 10/25/2022]
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10
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Fuengfuloy P, Chuawong P, Suebka S, Wattana-amorn P, Williams C, Crump MP, Songsiriritthigul C. Overproduction of the N-terminal anticodon-binding domain of the non-discriminating aspartyl-tRNA synthetase from Helicobacter pylori for crystallization and NMR measurements. Protein Expr Purif 2013; 89:25-32. [DOI: 10.1016/j.pep.2013.02.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 02/06/2013] [Accepted: 02/13/2013] [Indexed: 10/27/2022]
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11
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Akochy PM, Lapointe J, Roy PH. Natural insertion of the bro-1 β-lactamase gene into the gatCAB operon affects Moraxella catarrhalis aspartyl-tRNAAsn amidotransferase activity. Microbiology (Reading) 2012; 158:2363-2371. [DOI: 10.1099/mic.0.060095-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Affiliation(s)
- Pierre-Marie Akochy
- Centre de Recherche en Infectiologie, CHUQ Pavillon CHUL, 2705 boul. Laurier, RC-709, QC G1V 4G2, Canada
- Institut Pasteur de Côte d’Ivoire, 01 BP 490 Abidjan, Côte d’Ivoire
- Département de Biochimie, de Microbiologie et de Bio-informatique, Université Laval, QC G1V 0A6, Canada
| | - Jacques Lapointe
- Institut de biologie intégrative et des systèmes (IBIS), Pavillon Charles-Eugène-Marchand, G1V 0A6, Canada
- Département de Biochimie, de Microbiologie et de Bio-informatique, Université Laval, QC G1V 0A6, Canada
| | - Paul H. Roy
- Centre de Recherche en Infectiologie, CHUQ Pavillon CHUL, 2705 boul. Laurier, RC-709, QC G1V 4G2, Canada
- Département de Biochimie, de Microbiologie et de Bio-informatique, Université Laval, QC G1V 0A6, Canada
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12
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Saad NY, Schiel B, Brayé M, Heap JT, Minton NP, Dürre P, Becker HD. Riboswitch (T-box)-mediated control of tRNA-dependent amidation in Clostridium acetobutylicum rationalizes gene and pathway redundancy for asparagine and asparaginyl-trnaasn synthesis. J Biol Chem 2012; 287:20382-94. [PMID: 22505715 DOI: 10.1074/jbc.m111.332304] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Analysis of the Gram-positive Clostridium acetobutylicum genome reveals an inexplicable level of redundancy for the genes putatively involved in asparagine (Asn) and Asn-tRNA(Asn) synthesis. Besides a duplicated set of gatCAB tRNA-dependent amidotransferase genes, there is a triplication of aspartyl-tRNA synthetase genes and a duplication of asparagine synthetase B genes. This genomic landscape leads to the suspicion of the incoherent simultaneous use of the direct and indirect pathways of Asn and Asn-tRNA(Asn) formation. Through a combination of biochemical and genetic approaches, we show that C. acetobutylicum forms Asn and Asn-tRNA(Asn) by tRNA-dependent amidation. We demonstrate that an entire transamidation pathway composed of aspartyl-tRNA synthetase and one set of GatCAB genes is organized as an operon under the control of a tRNA(Asn)-dependent T-box riboswitch. Finally, our results suggest that this exceptional gene redundancy might be interconnected to control tRNA-dependent Asn synthesis, which in turn might be involved in controlling the metabolic switch from acidogenesis to solventogenesis in C. acetobutylicum.
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Affiliation(s)
- Nizar Y Saad
- Unité Mixte de Recherche "Génétique Moléculaire, Génomique, Microbiologie," CNRS, Université de Strasbourg, 21 rue René Descartes, 67084 Strasbourg, France
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13
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Chang KM, Hendrickson TL. Recognition of tRNAGln by Helicobacter pylori GluRS2--a tRNAGln-specific glutamyl-tRNA synthetase. Nucleic Acids Res 2009; 37:6942-9. [PMID: 19755501 PMCID: PMC2777447 DOI: 10.1093/nar/gkp754] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Accurate aminoacylation of tRNAs by the aminoacyl-tRNA synthetases (aaRSs) plays a critical role in protein translation. However, some of the aaRSs are missing in many microorganisms. Helicobacter pylori does not have a glutaminyl-tRNA synthetase (GlnRS) but has two divergent glutamyl-tRNA synthetases: GluRS1 and GluRS2. Like a canonical GluRS, GluRS1 aminoacylates tRNAGlu1 and tRNAGlu2. In contrast, GluRS2 only misacylates tRNAGln to form Glu-tRNAGln. It is not clear how GluRS2 achieves specific recognition of tRNAGln while rejecting the two H. pylori tRNAGlu isoacceptors. Here, we show that GluRS2 recognizes major identity elements clustered in the tRNAGln acceptor stem. Mutations in the tRNA anticodon or at the discriminator base had little to no impact on enzyme specificity and activity.
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Affiliation(s)
- Keng-Ming Chang
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA
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14
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Abstract
The accurate formation of cognate aminoacyl-transfer RNAs (aa-tRNAs) is essential for the fidelity of translation. Most amino acids are esterified onto their cognate tRNA isoacceptors directly by aa-tRNA synthetases. However, in the case of four amino acids (Gln, Asn, Cys and Sec), aminoacyl-tRNAs are made through indirect pathways in many organisms across all three domains of life. The process begins with the charging of noncognate amino acids to tRNAs by a specialized synthetase in the case of Cys-tRNA(Cys) formation or by synthetases with relaxed specificity, such as the non-discriminating glutamyl-tRNA, non-discriminating aspartyl-tRNA and seryl-tRNA synthetases. The resulting misacylated tRNAs are then converted to cognate pairs through transformation of the amino acids on the tRNA, which is catalyzed by a group of tRNA-dependent modifying enzymes, such as tRNA-dependent amidotransferases, Sep-tRNA:Cys-tRNA synthase, O-phosphoseryl-tRNA kinase and Sep-tRNA:Sec-tRNA synthase. The majority of these indirect pathways are widely spread in all domains of life and thought to be part of the evolutionary process.
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Affiliation(s)
- Jing Yuan
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
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15
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Bailly M, Blaise M, Roy H, Deniziak M, Lorber B, Birck C, Becker HD, Kern D. tRNA-dependent asparagine formation in prokaryotes: characterization, isolation and structural and functional analysis of a ribonucleoprotein particle generating Asn-tRNA(Asn). Methods 2008; 44:146-63. [PMID: 18241796 DOI: 10.1016/j.ymeth.2007.11.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Revised: 11/23/2007] [Accepted: 11/29/2007] [Indexed: 11/29/2022] Open
Abstract
In some living organisms the 20 aa-tRNA species participating in protein synthesis are not charged by a complete set of 20 aminoacyl-tRNA synthetases. In prokaryotes, the deficiency of asparaginyl- and/or glutaminyl-tRNA synthetases is compensated by another aminoacyl-tRNA synthetase of relaxed specificity that mischarges the orphan tRNA and by an enzyme that converts the amino acid into that homologous to the tRNA. In Thermus thermophilus Asn-tRNA(Asn) is formed indirectly via a two-step pathway whereby tRNA(Asn) is mischarged with Asp that will subsequently be amidated into Asn by an amidotransferase. The non-discriminating aspartyl-tRNA synthetase, the trimeric GatCAB tRNA-dependent amidotransferase and the tRNA(Asn) promoting this pathway assemble into a ribonucleoprotein particle termed transamidosome. This article deals with the methods and techniques employed to clone the genes encoding the enzymes and the tRNA involved in this pathway, to express them in Escherichia coli, to isolate them on a large scale, and to transcribe and produce mg quantities of pure tRNA(Asn)in vitro. The approaches designed especially for this system include (i) clustering of the ORFs encoding the subunits of the heterotrimeric GatCAB that are sprinkled in the genome into an artificial operon, and (ii) the self-cleavage of the tRNA(Asn) transcript starting with U in 5' position through fusion with a hammerhead ribozyme. Further, the crystallization of the free enzymes is described and the characterization of their assembly with tRNA(Asn) into a ribonucleoprotein particle, as well as the investigation of the catalytic mechanism of Asn-tRNA(Asn) formation by the complex are reported.
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Affiliation(s)
- Marc Bailly
- UPR 9002 Architecture et Réactivité de l'ARN, Institut de Biologie Moléculaire et Cellulaire du CNRS, 15 Rue René Descartes and Université Louis Pasteur, F-67084 Strasbourg Cedex, France
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16
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Sheppard K, Yuan J, Hohn MJ, Jester B, Devine KM, Söll D. From one amino acid to another: tRNA-dependent amino acid biosynthesis. Nucleic Acids Res 2008; 36:1813-25. [PMID: 18252769 PMCID: PMC2330236 DOI: 10.1093/nar/gkn015] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Aminoacyl-tRNAs (aa-tRNAs) are the essential substrates for translation. Most aa-tRNAs are formed by direct aminoacylation of tRNA catalyzed by aminoacyl-tRNA synthetases. However, a smaller number of aa-tRNAs (Asn-tRNA, Gln-tRNA, Cys-tRNA and Sec-tRNA) are made by synthesizing the amino acid on the tRNA by first attaching a non-cognate amino acid to the tRNA, which is then converted to the cognate one catalyzed by tRNA-dependent modifying enzymes. Asn-tRNA or Gln-tRNA formation in most prokaryotes requires amidation of Asp-tRNA or Glu-tRNA by amidotransferases that couple an amidase or an asparaginase to liberate ammonia with a tRNA-dependent kinase. Both archaeal and eukaryotic Sec-tRNA biosynthesis and Cys-tRNA synthesis in methanogens require O-phosophoseryl-tRNA formation. For tRNA-dependent Cys biosynthesis, O-phosphoseryl-tRNA synthetase directly attaches the amino acid to the tRNA which is then converted to Cys by Sep-tRNA: Cys-tRNA synthase. In Sec-tRNA synthesis, O-phosphoseryl-tRNA kinase phosphorylates Ser-tRNA to form the intermediate which is then modified to Sec-tRNA by Sep-tRNA:Sec-tRNA synthase. Complex formation between enzymes in the same pathway may protect the fidelity of protein synthesis. How these tRNA-dependent amino acid biosynthetic routes are integrated into overall metabolism may explain why they are still retained in so many organisms.
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Affiliation(s)
- Kelly Sheppard
- Department of Molecular Biophysics, Yale University, New Haven, CT 06520-8114, USA
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17
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Sheppard K, Sherrer RL, Söll D. Methanothermobacter thermautotrophicus tRNA Gln confines the amidotransferase GatCAB to asparaginyl-tRNA Asn formation. J Mol Biol 2008; 377:845-53. [PMID: 18291416 DOI: 10.1016/j.jmb.2008.01.064] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2007] [Revised: 01/15/2008] [Accepted: 01/16/2008] [Indexed: 10/22/2022]
Abstract
Many prokaryotes form the amide aminoacyl-tRNAs glutaminyl-tRNA and asparaginyl-tRNA by tRNA-dependent amidation of the mischarged tRNA species, glutamyl-tRNA(Gln) or aspartyl-tRNA(Asn). Archaea employ two such amidotransferases, GatCAB and GatDE, while bacteria possess only one, GatCAB. The Methanothermobacter thermautotrophicus GatDE is slightly more efficient using Asn as an amide donor than Gln (k(cat)/K(M) of 5.4 s(-1)/mM and 1.2 s(-1)/mM, respectively). Unlike the bacterial GatCAB enzymes studied to date, the M. thermautotrophicus GatCAB uses Asn almost as well as Gln as an amide donor (k(cat)/K(M) of 5.7 s(-1)/mM and 16.7 s(-1)/mM, respectively). In contrast to the initial characterization of the M. thermautotrophicus GatCAB as being able to form Asn-tRNA(Asn) and Gln-tRNA(Gln), our data demonstrate that while the enzyme is able to transamidate Asp-tRNA(Asn) (k(cat)/K(M) of 125 s(-1)/mM) it is unable to transamidate M. thermautotrophicus Glu-tRNA(Gln). However, M. thermautotrophicus GatCAB is capable of transamidating Glu-tRNA(Gln) from H. pylori or B. subtilis, and M. thermautotrophicus Glu-tRNA(Asn). Thus, M. thermautotrophicus encodes two amidotransferases, each with its own activity, GatDE for Gln-tRNA and GatCAB for Asn-tRNA synthesis.
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Affiliation(s)
- Kelly Sheppard
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
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18
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Sheppard K, Söll D. On the evolution of the tRNA-dependent amidotransferases, GatCAB and GatDE. J Mol Biol 2008; 377:831-44. [PMID: 18279892 DOI: 10.1016/j.jmb.2008.01.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2007] [Revised: 12/21/2007] [Accepted: 01/02/2008] [Indexed: 11/19/2022]
Abstract
Glutaminyl-tRNA synthetase and asparaginyl-tRNA synthetase evolved from glutamyl-tRNA synthetase and aspartyl-tRNA synthetase, respectively, after the split in the last universal communal ancestor (LUCA). Glutaminyl-tRNA(Gln) and asparaginyl-tRNA(Asn) were likely formed in LUCA by amidation of the mischarged species, glutamyl-tRNA(Gln) and aspartyl-tRNA(Asn), by tRNA-dependent amidotransferases, as is still the case in most bacteria and all known archaea. The amidotransferase GatCAB is found in both domains of life, while the heterodimeric amidotransferase GatDE is found only in Archaea. The GatB and GatE subunits belong to a unique protein family that includes Pet112 that is encoded in the nuclear genomes of numerous eukaryotes. GatE was thought to have evolved from GatB after the emergence of the modern lines of decent. Our phylogenetic analysis though places the split between GatE and GatB, prior to the phylogenetic divide between Bacteria and Archaea, and Pet112 to be of mitochondrial origin. In addition, GatD appears to have emerged prior to the bacterial-archaeal phylogenetic divide. Thus, while GatDE is an archaeal signature protein, it likely was present in LUCA together with GatCAB. Archaea retained both amidotransferases, while Bacteria emerged with only GatCAB. The presence of GatDE has favored a unique archaeal tRNA(Gln) that may be preventing the acquisition of glutaminyl-tRNA synthetase in Archaea. Archaeal GatCAB, on the other hand, has not favored a distinct tRNA(Asn), suggesting that tRNA(Asn) recognition is not a major barrier to the retention of asparaginyl-tRNA synthetase in many Archaea.
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Affiliation(s)
- Kelly Sheppard
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
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19
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Namgoong S, Sheppard K, Sherrer RL, Söll D. Co-evolution of the archaeal tRNA-dependent amidotransferase GatCAB with tRNA(Asn). FEBS Lett 2007; 581:309-14. [PMID: 17214986 PMCID: PMC1808439 DOI: 10.1016/j.febslet.2006.12.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2006] [Revised: 12/12/2006] [Accepted: 12/13/2006] [Indexed: 12/01/2022]
Abstract
The important identity elements in tRNA(Gln) and tRNA(Asn) for bacterial GatCAB and in tRNA(Gln) for archaeal GatDE are the D-loop and the first base pair of the acceptor stem. Here we show that Methanothermobacter thermautotrophicus GatCAB, the archaeal enzyme, is different as it discriminates Asp-tRNA(Asp) and Asp-tRNA(Asn) by use of U49, the D-loop and to a lesser extent the variable loop. Since archaea possess the tRNA(Gln)-specific amidotransferase GatDE, the archaeal GatCAB enzyme evolved to recognize different elements in tRNA(Asn) than those recognized by GatDE or by the bacterial GatCAB enzyme in their tRNA substrates.
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Affiliation(s)
- Suk Namgoong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520 8114, USA
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20
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Cathopoulis T, Chuawong P, Hendrickson TL. Novel tRNA aminoacylation mechanisms. MOLECULAR BIOSYSTEMS 2007; 3:408-18. [PMID: 17533454 DOI: 10.1039/b618899k] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In nature, ribosomally synthesized proteins can contain at least 22 different amino acids: the 20 common amino acids as well as selenocysteine and pyrrolysine. Each of these amino acids is inserted into proteins codon-specifically via an aminoacyl-transfer RNA (aa-tRNA). In most cases, these aa-tRNAs are biosynthesized directly by a set of highly specific and accurate aminoacyl-tRNA synthetases (aaRSs). However, in some cases aaRSs with relaxed or novel substrate specificities cooperate with other enzymes to generate specific canonical and non-canonical aminoacyl-tRNAs.
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MESH Headings
- Amino Acyl-tRNA Synthetases/metabolism
- Aspartate-tRNA Ligase/metabolism
- Bacteria/enzymology
- RNA, Transfer, Amino Acyl/biosynthesis
- RNA, Transfer, Amino Acyl/chemistry
- RNA, Transfer, Amino Acyl/metabolism
- RNA, Transfer, Asn/biosynthesis
- RNA, Transfer, Asn/chemistry
- RNA, Transfer, Cys/biosynthesis
- RNA, Transfer, Cys/chemistry
- RNA, Transfer, Gln/biosynthesis
- RNA, Transfer, Gln/chemistry
- Transfer RNA Aminoacylation
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Affiliation(s)
- Terry Cathopoulis
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
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21
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Cathopoulis TJT, Chuawong P, Hendrickson TL. A thin-layer electrophoretic assay for Asp-tRNAAsn/Glu-tRNAGln amidotransferase. Anal Biochem 2006; 360:151-3. [PMID: 17113030 PMCID: PMC1800913 DOI: 10.1016/j.ab.2006.10.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2006] [Revised: 10/17/2006] [Accepted: 10/18/2006] [Indexed: 11/26/2022]
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22
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Bailly M, Giannouli S, Blaise M, Stathopoulos C, Kern D, Becker HD. A single tRNA base pair mediates bacterial tRNA-dependent biosynthesis of asparagine. Nucleic Acids Res 2006; 34:6083-94. [PMID: 17074748 PMCID: PMC1635274 DOI: 10.1093/nar/gkl622] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In many prokaryotes and in organelles asparagine and glutamine are formed by a tRNA-dependent amidotransferase (AdT) that catalyzes amidation of aspartate and glutamate, respectively, mischarged on tRNAAsn and tRNAGln. These pathways supply the deficiency of the organism in asparaginyl- and glutaminyl-tRNA synthtetases and provide the translational machinery with Asn-tRNAAsn and Gln-tRNAGln. So far, nothing is known about the structural elements that confer to tRNA the role of a specific cofactor in the formation of the cognate amino acid. We show herein, using aspartylated tRNAAsn and tRNAAsp variants, that amidation of Asp acylating tRNAAsn is promoted by the base pair U1-A72 whereas the G1-C72 pair and presence of the supernumerary nucleotide U20A in the D-loop of tRNAAsp prevent amidation. We predict, based on comparison of tRNAGln and tRNAGlu sequence alignments from bacteria using the AdT-dependent pathway to form Gln-tRNAGln, that the same combination of nucleotides also rules specific tRNA-dependent formation of Gln. In contrast, we show that the tRNA-dependent conversion of Asp into Asn by archaeal AdT is mainly mediated by nucleotides G46 and U47 of the variable region. In the light of these results we propose that bacterial and archaeal AdTs use kingdom-specific signals to catalyze the tRNA-dependent formations of Asn and Gln.
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MESH Headings
- Adenine/chemistry
- Asparagine/biosynthesis
- Base Sequence
- Kinetics
- Neisseria meningitidis/enzymology
- Nitrogenous Group Transferases/chemistry
- Nitrogenous Group Transferases/metabolism
- RNA, Archaeal/chemistry
- RNA, Archaeal/metabolism
- RNA, Bacterial/chemistry
- RNA, Bacterial/metabolism
- RNA, Transfer/chemistry
- RNA, Transfer/metabolism
- RNA, Transfer, Asn/chemistry
- RNA, Transfer, Asn/metabolism
- RNA, Transfer, Asp/chemistry
- RNA, Transfer, Asp/metabolism
- RNA, Transfer, Gln/chemistry
- RNA, Transfer, Gln/metabolism
- RNA, Transfer, Glu/chemistry
- RNA, Transfer, Glu/metabolism
- Sequence Alignment
- Species Specificity
- Substrate Specificity
- Uridine/chemistry
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Affiliation(s)
| | - Stamatina Giannouli
- Department of Biochemistry and Biotechnology, University of Thessaly26 Ploutonos street, 41221 Larissa, Greece
| | | | - Constantinos Stathopoulos
- Department of Biochemistry and Biotechnology, University of Thessaly26 Ploutonos street, 41221 Larissa, Greece
- To whom correspondence should be addressed. Tel: +33 3 88 41 70 92; Fax: +33 3 88 60 22 18;
| | - Daniel Kern
- To whom correspondence should be addressed. Tel: +33 3 88 41 70 92; Fax: +33 3 88 60 22 18;
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23
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Chuawong P, Hendrickson TL. The nondiscriminating aspartyl-tRNA synthetase from Helicobacter pylori: anticodon-binding domain mutations that impact tRNA specificity and heterologous toxicity. Biochemistry 2006; 45:8079-87. [PMID: 16800632 PMCID: PMC2654173 DOI: 10.1021/bi060189c] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Divergent tRNA substrate recognition patterns distinguish the two distinct forms of aspartyl-tRNA synthetase (AspRS) that exist in different bacteria. In some cases, a canonical, discriminating AspRS (D-AspRS) specifically generates Asp-tRNA(Asp) and usually coexists with asparaginyl-tRNA synthetase (AsnRS). In other bacteria, particularly those that lack AsnRS, AspRS is nondiscriminating (ND-AspRS) and generates both Asp-tRNA(Asp) and the noncanonical, misacylated Asp-tRNA(Asn); this misacylated tRNA is subsequently repaired by the glutamine-dependent Asp-tRNA(Asn)/Glu-tRNA(Gln) amidotransferase (Asp/Glu-Adt). The molecular features that distinguish the closely related bacterial D-AspRS and ND-AspRS are not well-understood. Here, we report the first characterization of the ND-AspRS from the human pathogen Helicobacter pylori (H. pylori or Hp). This enzyme is toxic when heterologously overexpressed in Escherichia coli. This toxicity is rescued upon coexpression of the Hp Asp/Glu-Adt, indicating that Hp Asp/Glu-Adt can utilize E. coli Asp-tRNA(Asn) as a substrate. Finally, mutations in the anticodon-binding domain of Hp ND-AspRS reduce this enzyme's ability to misacylate tRNA(Asn), in a manner that correlates with the toxicity of the enzyme in E. coli.
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24
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Nakamura A, Yao M, Chimnaronk S, Sakai N, Tanaka I. Ammonia channel couples glutaminase with transamidase reactions in GatCAB. Science 2006; 312:1954-8. [PMID: 16809541 DOI: 10.1126/science.1127156] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The formation of glutaminyl transfer RNA (Gln-tRNA(Gln)) differs among the three domains of life. Most bacteria employ an indirect pathway to produce Gln-tRNA(Gln) by a heterotrimeric glutamine amidotransferase CAB (GatCAB) that acts on the misacylated Glu-tRNA(Gln). Here, we describe a series of crystal structures of intact GatCAB from Staphylococcus aureus in the apo form and in the complexes with glutamine, asparagine, Mn2+, and adenosine triphosphate analog. Two identified catalytic centers for the glutaminase and transamidase reactions are markedly distant but connected by a hydrophilic ammonia channel 30 A in length. Further, we show that the first U-A base pair in the acceptor stem and the D loop of tRNA(Gln) serve as identity elements essential for discrimination by GatCAB and propose a complete model for the overall concerted reactions to synthesize Gln-tRNA(Gln).
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MESH Headings
- Adenosine Diphosphate/metabolism
- Amino Acid Sequence
- Aminoacyltransferases/metabolism
- Ammonia/metabolism
- Apoenzymes/chemistry
- Apoenzymes/metabolism
- Asparagine/metabolism
- Base Pairing
- Catalytic Domain
- Crystallography, X-Ray
- Glutaminase/metabolism
- Glutamine/chemistry
- Glutamine/metabolism
- Hydrogen Bonding
- Hydrophobic and Hydrophilic Interactions
- Magnesium/metabolism
- Manganese/metabolism
- Models, Molecular
- Molecular Sequence Data
- Mutation
- Nucleic Acid Conformation
- Protein Structure, Quaternary
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Protein Subunits
- RNA, Bacterial/chemistry
- RNA, Bacterial/metabolism
- RNA, Transfer, Amino Acyl/chemistry
- RNA, Transfer, Amino Acyl/metabolism
- RNA, Transfer, Gln/chemistry
- RNA, Transfer, Gln/metabolism
- Staphylococcus aureus/enzymology
- Staphylococcus aureus/genetics
- Staphylococcus aureus/metabolism
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Affiliation(s)
- Akiyoshi Nakamura
- Faculty of Advanced Life Sciences, Hokkaido University, Sapporo 060-0810, Japan
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25
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Bernard D, Akochy PM, Beaulieu D, Lapointe J, Roy PH. Two residues in the anticodon recognition domain of the aspartyl-tRNA synthetase from Pseudomonas aeruginosa are individually implicated in the recognition of tRNAAsn. J Bacteriol 2006; 188:269-74. [PMID: 16352843 PMCID: PMC1317590 DOI: 10.1128/jb.188.1.269-274.2006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In many organisms, the formation of asparaginyl-tRNA is not done by direct aminoacylation of tRNA(Asn) but by specific tRNA-dependent transamidation of aspartyl-tRNA(Asn). This transamidation pathway involves a nondiscriminating aspartyl-tRNA synthetase (AspRS) that charges both tRNA(Asp) and tRNA(Asn) with aspartic acid. Recently, it has been shown for the first time in an organism (Pseudomonas aeruginosa PAO1) that the transamidation pathway is the only route of synthesis of Asn-tRNA(Asn) but does not participate in Gln-tRNA(Gln) formation. P. aeruginosa PAO1 has a nondiscriminating AspRS. We report here the identification of two residues in the anticodon recognition domain (H31 and G83) which are implicated in the recognition of tRNA(Asn). Sequence comparisons of putative discriminating and nondiscriminating AspRSs (based on the presence or absence of the AdT operon and of AsnRS) revealed that bacterial nondiscriminating AspRSs possess a histidine at position 31 and usually a glycine at position 83, whereas discriminating AspRSs possess a leucine at position 31 and a residue other than a glycine at position 83. Mutagenesis of these residues of P. aeruginosa AspRS from histidine to leucine and from glycine to lysine increased the specificity of tRNA(Asp) charging over that of tRNA(Asn) by 3.5-fold and 4.2-fold, respectively. Thus, we show these residues to be determinants of the relaxed specificity of this nondiscriminating AspRS. Using available crystallographic data, we found that the H31 residue could interact with the central bases of the anticodons of the tRNA(Asp) and tRNA(Asn). Therefore, these two determinants of specificity of P. aeruginosa AspRS could be important for all bacterial AspRSs.
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Affiliation(s)
- Dominic Bernard
- Centre de Recherche en Infectiologie, CHU Laval, 2705 Boulevard Laurier, RC-709, Sainte-Foy, Quebec, Canada G1V 4G2
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26
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Schmitt E, Panvert M, Blanquet S, Mechulam Y. Structural Basis for tRNA-Dependent Amidotransferase Function. Structure 2005; 13:1421-33. [PMID: 16216574 DOI: 10.1016/j.str.2005.06.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2005] [Revised: 06/20/2005] [Accepted: 06/30/2005] [Indexed: 11/26/2022]
Abstract
Besides direct charging of tRNAs by aminoacyl-tRNA synthetases, indirect routes also ensure attachment of some amino acids onto tRNA. Such routes may explain how new amino acids entered into protein synthesis. In archaea and in most bacteria, tRNA(Gln) is first misaminoacylated by glutamyl-tRNA synthetase. Glu-tRNA(Gln) is then matured into Gln-tRNA(Gln) by a tRNA-dependent amidotransferase. We report the structure of a tRNA-dependent amidotransferase-that of GatDE from Pyrococcus abyssi. The 3.0 A resolution crystal structure shows a tetramer with two GatD molecules as the core and two GatE molecules at the periphery. The fold of GatE cannot be related to that of any tRNA binding enzyme. The ammonium donor site on GatD and the tRNA site on GatE are markedly distant. Comparison of GatD and L-asparaginase structures shows how the motion of a beta hairpin region containing a crucial catalytic threonine may control the overall reaction cycle of GatDE.
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MESH Headings
- Amino Acid Sequence
- Amino Acyl-tRNA Synthetases/chemistry
- Amino Acyl-tRNA Synthetases/metabolism
- Binding Sites
- Conserved Sequence
- Crystallography, X-Ray
- Dimerization
- Glutamate-tRNA Ligase/chemistry
- Glutamate-tRNA Ligase/metabolism
- Models, Molecular
- Molecular Sequence Data
- Nitrogenous Group Transferases/chemistry
- Nitrogenous Group Transferases/genetics
- Nitrogenous Group Transferases/metabolism
- Protein Biosynthesis
- Protein Folding
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Protein Subunits/chemistry
- Pyrococcus abyssi/enzymology
- RNA, Archaeal/chemistry
- RNA, Archaeal/genetics
- RNA, Archaeal/metabolism
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Transfer/chemistry
- RNA, Transfer/metabolism
- RNA, Transfer, Gln/metabolism
- Sequence Homology, Amino Acid
- Threonine/chemistry
- X-Ray Diffraction
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Affiliation(s)
- Emmanuelle Schmitt
- Laboratoire de Biochimie, Unité Mixte de Recherche 7654, CNRS-Ecole Polytechnique, F-91128 Palaiseau cedex, France.
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27
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Ward N, Larsen Ø, Sakwa J, Bruseth L, Khouri H, Durkin AS, Dimitrov G, Jiang L, Scanlan D, Kang KH, Lewis M, Nelson KE, Methé B, Wu M, Heidelberg JF, Paulsen IT, Fouts D, Ravel J, Tettelin H, Ren Q, Read T, DeBoy RT, Seshadri R, Salzberg SL, Jensen HB, Birkeland NK, Nelson WC, Dodson RJ, Grindhaug SH, Holt I, Eidhammer I, Jonasen I, Vanaken S, Utterback T, Feldblyum TV, Fraser CM, Lillehaug JR, Eisen JA. Genomic insights into methanotrophy: the complete genome sequence of Methylococcus capsulatus (Bath). PLoS Biol 2004; 2:e303. [PMID: 15383840 PMCID: PMC517821 DOI: 10.1371/journal.pbio.0020303] [Citation(s) in RCA: 204] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2004] [Accepted: 07/14/2004] [Indexed: 11/23/2022] Open
Abstract
Methanotrophs are ubiquitous bacteria that can use the greenhouse gas methane as a sole carbon and energy source for growth, thus playing major roles in global carbon cycles, and in particular, substantially reducing emissions of biologically generated methane to the atmosphere. Despite their importance, and in contrast to organisms that play roles in other major parts of the carbon cycle such as photosynthesis, no genome-level studies have been published on the biology of methanotrophs. We report the first complete genome sequence to our knowledge from an obligate methanotroph, Methylococcus capsulatus (Bath), obtained by the shotgun sequencing approach. Analysis revealed a 3.3-Mb genome highly specialized for a methanotrophic lifestyle, including redundant pathways predicted to be involved in methanotrophy and duplicated genes for essential enzymes such as the methane monooxygenases. We used phylogenomic analysis, gene order information, and comparative analysis with the partially sequenced methylotroph Methylobacterium extorquens to detect genes of unknown function likely to be involved in methanotrophy and methylotrophy. Genome analysis suggests the ability of M. capsulatus to scavenge copper (including a previously unreported nonribosomal peptide synthetase) and to use copper in regulation of methanotrophy, but the exact regulatory mechanisms remain unclear. One of the most surprising outcomes of the project is evidence suggesting the existence of previously unsuspected metabolic flexibility in M. capsulatus, including an ability to grow on sugars, oxidize chemolithotrophic hydrogen and sulfur, and live under reduced oxygen tension, all of which have implications for methanotroph ecology. The availability of the complete genome of M. capsulatus (Bath) deepens our understanding of methanotroph biology and its relationship to global carbon cycles. We have gained evidence for greater metabolic flexibility than was previously known, and for genetic components that may have biotechnological potential.
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Affiliation(s)
- Naomi Ward
- The Institute for Genomic Research, Rockville, Maryland, USA.
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28
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Akochy PM, Bernard D, Roy PH, Lapointe J. Direct glutaminyl-tRNA biosynthesis and indirect asparaginyl-tRNA biosynthesis in Pseudomonas aeruginosa PAO1. J Bacteriol 2004; 186:767-76. [PMID: 14729703 PMCID: PMC321480 DOI: 10.1128/jb.186.3.767-776.2004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genomic sequence of Pseudomonas aeruginosa PAO1 was searched for the presence of open reading frames (ORFs) encoding enzymes potentially involved in the formation of Gln-tRNA and of Asn-tRNA. We found ORFs similar to known glutamyl-tRNA synthetases (GluRS), glutaminyl-tRNA synthetases (GlnRS), aspartyl-tRNA synthetases (AspRS), and trimeric tRNA-dependent amidotransferases (AdT) but none similar to known asparaginyl-tRNA synthetases (AsnRS). The absence of AsnRS was confirmed by biochemical tests with crude and fractionated extracts of P. aeruginosa PAO1, with the homologous tRNA as the substrate. The characterization of GluRS, AspRS, and AdT overproduced from their cloned genes in P. aeruginosa and purified to homogeneity revealed that GluRS is discriminating in the sense that it does not glutamylate tRNA(Gln), that AspRS is nondiscriminating, and that its Asp-tRNA(Asn) product is transamidated by AdT. On the other hand, tRNA(Gln) is directly glutaminylated by GlnRS. These results show that P. aeruginosa PAO1 is the first organism known to synthesize Asn-tRNA via the indirect pathway and to synthesize Gln-tRNA via the direct pathway. The essential role of AdT in the formation of Asn-tRNA in P. aeruginosa and the absence of a similar activity in the cytoplasm of eukaryotic cells identifies AdT as a potential target for antibiotics to be designed against this human pathogen. Such novel antibiotics could be active against other multidrug-resistant gram-negative pathogens such as Burkholderia and Neisseria as well as all pathogenic gram-positive bacteria.
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Affiliation(s)
- Pierre-Marie Akochy
- Département de Biochimie et de Microbiologie, Faculté des Sciences et de Génie, Université Laval, Québec, Canada G1K 7P4
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Shrestha R, Dixon RA, Chapman KD. Molecular identification of a functional homologue of the mammalian fatty acid amide hydrolase in Arabidopsis thaliana. J Biol Chem 2003; 278:34990-7. [PMID: 12824167 DOI: 10.1074/jbc.m305613200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
N-Acylethanolamines (NAEs) are endogenous constituents of plant and animal tissues, and in vertebrates their hydrolysis terminates their participation as lipid mediators in the endocannabinoid signaling system. The membrane-bound enzyme responsible for NAE hydrolysis in mammals has been identified at the molecular level (designated fatty acid amide hydrolase, FAAH), and although an analogous enzyme activity was identified in microsomes of cotton seedlings, no molecular information is available for this enzyme in plants. Here we report the identification, the heterologous expression (in Escherichia coli), and the biochemical characterization of an Arabidopsis thaliana FAAH homologue. Candidate Arabidopsis DNA sequences containing a characteristic amidase signature sequence (PS00571) were identified in plant genome data bases, and a cDNA was isolated by reverse transcriptase-PCR using Arabidopsis genome sequences to develop appropriate oligonucleotide primers. The cDNA was sequenced and predicted to encode a protein of 607 amino acids with 37% identity to rat FAAH within the amidase signature domain (18% over the entire length). Residues determined to be important for FAAH catalysis were conserved between the Arabidopsis and rat protein sequences. In addition, a single transmembrane domain near the N terminus was predicted in the Arabidopsis protein sequence, similar to that of the rat FAAH protein. The putative plant FAAH cDNA was expressed as an epitope/His-tagged fusion protein in E. coli and solubilized from cell lysates in the nonionic detergent, dodecyl maltoside. Affinity-purified recombinant protein was indeed active in hydrolyzing a variety of naturally occurring N-acylethanolamine types. Kinetic parameters and inhibition data for the recombinant Arabidopsis protein were consistent with these properties of the enzyme activity characterized previously in plant and animal systems. Collectively these data now provide support at the molecular level for a conserved mechanism between plants and animals for the metabolism of NAEs.
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Affiliation(s)
- Rhidaya Shrestha
- Department of Biological Sciences, Division of Biochemistry and Molecular Biology, University of North Texas, Denton, Texas 76203, USA
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Stathopoulos C, Ahel I, Ali K, Ambrogelly A, Becker H, Bunjun S, Feng L, Herring S, Jacquin-Becker C, Kobayashi H, Korencic D, Krett B, Mejlhede N, Min B, Nakano H, Namgoong S, Polycarpo C, Raczniak G, Rinehart J, Rosas-Sandoval G, Ruan B, Sabina J, Sauerwald A, Toogood H, Tumbula-Hansen D, Ibba M, Söll D. Aminoacyl-tRNA synthesis: a postgenomic perspective. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2003; 66:175-83. [PMID: 12762020 DOI: 10.1101/sqb.2001.66.175] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- C Stathopoulos
- Departments of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA
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31
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Min B, Kitabatake M, Polycarpo C, Pelaschier J, Raczniak G, Ruan B, Kobayashi H, Namgoong S, Söll D. Protein synthesis in Escherichia coli with mischarged tRNA. J Bacteriol 2003; 185:3524-6. [PMID: 12775689 PMCID: PMC156233 DOI: 10.1128/jb.185.12.3524-3526.2003] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two types of aspartyl-tRNA synthetase exist: the discriminating enzyme (D-AspRS) forms only Asp-tRNA(Asp), while the nondiscriminating one (ND-AspRS) also synthesizes Asp-tRNA(Asn), a required intermediate in protein synthesis in many organisms (but not in Escherichia coli). On the basis of the E. coli trpA34 missense mutant transformed with heterologous ND-aspS genes, we developed a system with which to measure the in vivo formation of Asp-tRNA(Asn) and its acceptance by elongation factor EF-Tu. While large amounts of Asp-tRNA(Asn) are detrimental to E. coli, smaller amounts support protein synthesis and allow the formation of up to 38% of the wild-type level of missense-suppressed tryptophan synthetase.
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Affiliation(s)
- Bokkee Min
- Department of Molecular Biophysics, Yale University, New Haven, Connecticut 06520-8114, USA
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32
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Friedrich A, Prust C, Hartsch T, Henne A, Averhoff B. Molecular analyses of the natural transformation machinery and identification of pilus structures in the extremely thermophilic bacterium Thermus thermophilus strain HB27. Appl Environ Microbiol 2002; 68:745-55. [PMID: 11823215 PMCID: PMC126729 DOI: 10.1128/aem.68.2.745-755.2002] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thermus thermophilus HB27, an extremely thermophilic bacterium, exhibits high competence for natural transformation. To identify genes of the natural transformation machinery of T. thermophilus HB27, we performed homology searches in the partially completed T. thermophilus genomic sequence for conserved competence genes. These analyses resulted in the detection of 28 open reading frames (ORFs) exhibiting significant similarities to known competence proteins of gram-negative and gram-positive bacteria. Disruption of 15 selected potential competence genes led to the identification of 8 noncompetent mutants and one transformation-deficient mutant with a 100-fold reduced transformation frequency. One competence protein is similar to DprA of Haemophilus influenzae, seven are similar to type IV pilus proteins of Pseudomonas aeruginosa or Neisseria gonorrhoeae (PilM, PilN, PilO, PilQ, PilF, PilC, PilD), and another deduced protein (PilW) is similar to a protein of unknown function in Deinococcus radiodurans R1. Analysis of the piliation phenotype of T. thermophilus HB27 revealed the presence of single pilus structures on the surface of the wild-type cells, whereas the noncompetent pil mutants of Thermus, with the exception of the pilF mutant, were devoid of pilus structures. These results suggest that pili and natural transformation in T. thermophilus HB27 are functionally linked.
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Affiliation(s)
- Alexandra Friedrich
- Institut für Genetik und Mikrobiologie, Ludwig-Maximilians-Universität, Maria-Ward-Strasse 1a, D-80638 Münich, Germany
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33
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Raczniak G, Becker HD, Min B, Söll D. A single amidotransferase forms asparaginyl-tRNA and glutaminyl-tRNA in Chlamydia trachomatis. J Biol Chem 2001; 276:45862-7. [PMID: 11585842 DOI: 10.1074/jbc.m109494200] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Aminoacyl-tRNA is generally formed by aminoacyl-tRNA synthetases, a family of 20 enzymes essential for accurate protein synthesis. However, most bacteria generate one of the two amide aminoacyl-tRNAs, Asn-tRNA or Gln-tRNA, by transamidation of mischarged Asp-tRNA(Asn) or Glu-tRNA(Gln) catalyzed by a heterotrimeric amidotransferase (encoded by the gatA, gatB, and gatC genes). The Chlamydia trachomatis genome sequence reveals genes for 18 synthetases, whereas those for asparaginyl-tRNA synthetase and glutaminyl-tRNA synthetase are absent. Yet the genome harbors three gat genes in an operon-like arrangement (gatCAB). We reasoned that Chlamydia uses the gatCAB-encoded amidotransferase to generate both Asn-tRNA and Gln-tRNA. C. trachomatis aspartyl-tRNA synthetase and glutamyl-tRNA synthetase were shown to be non-discriminating synthetases that form the misacylated tRNA(Asn) and tRNA(Gln) species. A preparation of pure heterotrimeric recombinant C. trachomatis amidotransferase converted Asp-tRNA(Asn) and Glu-tRNA(Gln) into Asn-tRNA and Gln-tRNA, respectively. The enzyme used glutamine, asparagine, or ammonia as amide donors in the presence of either ATP or GTP. These results suggest that C. trachomatis employs the dual specificity gatCAB-encoded amidotransferase and 18 aminoacyl-tRNA synthetases to create the complete set of 20 aminoacyl-tRNAs.
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Affiliation(s)
- G Raczniak
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA
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Horiuchi KY, Harpel MR, Shen L, Luo Y, Rogers KC, Copeland RA. Mechanistic studies of reaction coupling in Glu-tRNAGln amidotransferase. Biochemistry 2001; 40:6450-7. [PMID: 11371208 DOI: 10.1021/bi002599l] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Organisms lacking Gln-tRNA synthetase produce Gln-tRNA(Gln) from misacylated Glu-tRNA(Gln) through the transamidation activity of Glu-tRNA(Gln) amidotransferase (Glu-AdT). Glu-AdT hydrolyzes Gln to Glu and NH(3), using the latter product to transamidate Glu-tRNA(Gln) in concert with ATP hydrolysis. In the absence of the amido acceptor, Glu-tRNA(Gln), the enzyme has basal glutaminase activity that is unaffected by ATP. However, Glu-tRNA(Gln) activates the glutaminase activity of the enzyme about 10-fold; addition of ATP elicits a further 7-fold increase. These enhanced activities mainly result from increases in k(cat) without significant effects on the K(m) for Gln. To determine if ATP binding is sufficient to induce full activation, we tested a variety of ATP analogues for their ability to stimulate tRNA-dependent glutaminase activity. Despite their binding to Glu-AdT, none of the ATP analogues induced glutaminase activation except ATP-gammaS, which stimulates glutaminase activity to the same level as ATP, but without formation of Gln-tRNA(Gln). ATP-gammaS hydrolysis by Glu-AdT is very low in the absence or presence of Glu-tRNA(Gln) and Gln. In contrast, Glu-tRNA(Gln) stimulates basal ATP hydrolysis slightly, but full activation of ATP hydrolysis requires both Gln and Glu-tRNA(Gln). Simultaneous monitoring of ATP or ATP-gammaS hydrolysis and glutaminase and transamidase activities reveals tight coupling among these activities in the presence of ATP, with all three activities waning in concert when Glu-tRNA(Gln) levels become exhausted. ATP-gammaS stimulates the glutaminase activity to an extent similar to that with ATP, but without concomitant transamidase activity and with a very low level of ATP-gammaS hydrolysis. This uncoupling between ATP-gammaS hydrolysis and glutaminase activities suggests that the activation of glutaminase activity by ATP or ATP-gammaS, together with Glu-tRNA(Gln), results either from an allosteric effect due simply to binding of these analogues to the enzyme or from some structural changes that attend ATP or ATP-gammaS hydrolysis.
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Affiliation(s)
- K Y Horiuchi
- Chemical Enzymology and Antimicrobials Departments, DuPont Pharmaceuticals Company, Experimental Station, Wilmington, Delaware 19880, USA.
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35
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Salazar JC, Zúñiga R, Raczniak G, Becker H, Söll D, Orellana O. A dual-specific Glu-tRNA(Gln) and Asp-tRNA(Asn) amidotransferase is involved in decoding glutamine and asparagine codons in Acidithiobacillus ferrooxidans. FEBS Lett 2001; 500:129-31. [PMID: 11445070 DOI: 10.1016/s0014-5793(01)02600-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The gatC, gatA and gatB genes encoding the three subunits of glutamyl-tRNA(Gln) amidotransferase from Acidithiobacillus ferrooxidans, an acidophilic bacterium used in bioleaching of minerals, have been cloned and expressed in Escherichia coli. As in Bacillus subtilis the three gat genes are organized in an operon-like structure in A. ferrooxidans. The heterologously overexpressed enzyme converts Glu-tRNA(Gln) to Gln-tRNA(Gln) and Asp-tRNA(Asn) to Asn-tRNA(Asn). Biochemical analysis revealed that neither glutaminyl-tRNA synthetase nor asparaginyl-tRNA synthetase is present in A. ferrooxidans, but that glutamyl-tRNA synthetase and aspartyl-tRNA synthetase enzymes are present in the organism. These data suggest that the transamidation pathway is responsible for the formation of Gln-tRNA and Asn-tRNA in A. ferrooxidans.
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Affiliation(s)
- J C Salazar
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
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36
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Raczniak G, Ibba M, Söll D. Genomics-based identification of targets in pathogenic bacteria for potential therapeutic and diagnostic use. Toxicology 2001; 160:181-9. [PMID: 11246138 DOI: 10.1016/s0300-483x(00)00454-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The availability of numerous complete microbial genome sequences has profoundly altered our understanding of a number of fundamental biological processes. For example the enzymes involved in aminoacyl-tRNA (AA-tRNA) synthesis, the key process responsible for the accuracy of protein synthesis, have been found to be highly species-specific. In particular, a number of pathogens contain certain pathways of AA-tRNA synthesis that are unrelated to those found in their mammalian hosts. Since AA-tRNA synthesis is indispensable for cell viability, the discovery of pathogen-specific pathways and enzymes presents novel therapeutic and diagnostic targets. Here we will review recent advances in the elucidation of AA-tRNA synthesis pathways and discuss the possible pharmaceutical exploitation of these discoveries. In particular, the integration of genomic and biochemical approaches to identify novel targets for the treatment of Chlamydial infections and the diagnosis and treatment of Lyme disease will be presented.
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Affiliation(s)
- G Raczniak
- Department of Molecular Biophysics and Biochemistry, Yale University, PO Box 208114, 266 Whitney Avenue, New Haven, CT 06520-8114, USA
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