1
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Pellegrino GM, Browne TS, Sharath K, Bari KA, Vancuren S, Allen-Vercoe E, Gloor GB, Edgell DR. Metabolically-targeted dCas9 expression in bacteria. Nucleic Acids Res 2023; 51:982-996. [PMID: 36629257 PMCID: PMC9881133 DOI: 10.1093/nar/gkac1248] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 12/11/2022] [Accepted: 12/14/2022] [Indexed: 01/12/2023] Open
Abstract
The ability to restrict gene expression to a relevant bacterial species in a complex microbiome is an unsolved problem. In the context of the human microbiome, one desirable target metabolic activity are glucuronide-utilization enzymes (GUS) that are implicated in the toxic re-activation of glucuronidated compounds in the human gastrointestinal (GI) tract, including the chemotherapeutic drug irinotecan. Here, we take advantage of the variable distribution of GUS enzymes in bacteria as a means to distinguish between bacteria with GUS activity, and re-purpose the glucuronide-responsive GusR transcription factor as a biosensor to regulate dCas9 expression in response to glucuronide inducers. We fused the Escherichia coli gusA regulatory region to the dCas9 gene to create pGreg-dCas9, and showed that dCas9 expression is induced by glucuronides, but not other carbon sources. When conjugated from E. coli to Gammaproteobacteria derived from human stool, dCas9 expression from pGreg-dCas9 was restricted to GUS-positive bacteria. dCas9-sgRNAs targeted to gusA specifically down-regulated gus operon transcription in Gammaproteobacteria, with a resulting ∼100-fold decrease in GusA activity. Our data outline a general strategy to re-purpose bacterial transcription factors responsive to exogenous metabolites for precise ligand-dependent expression of genetic tools such as dCas9 in diverse bacterial species.
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Affiliation(s)
- Gregory M Pellegrino
- Schulich School of Medicine and Dentistry, Department of Biochemistry, London, Ontario N6A 5C1, Canada
| | - Tyler S Browne
- Schulich School of Medicine and Dentistry, Department of Biochemistry, London, Ontario N6A 5C1, Canada
| | - Keerthana Sharath
- Schulich School of Medicine and Dentistry, Department of Biochemistry, London, Ontario N6A 5C1, Canada
| | - Khaleda A Bari
- Schulich School of Medicine and Dentistry, Department of Biochemistry, London, Ontario N6A 5C1, Canada
| | - Sarah J Vancuren
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Emma Allen-Vercoe
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Gregory B Gloor
- Schulich School of Medicine and Dentistry, Department of Biochemistry, London, Ontario N6A 5C1, Canada
| | - David R Edgell
- To whom correspondence should be addressed. Tel: +1 519 661 3133; Fax: +1 519 661 3175;
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2
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Tutukina MN, Dakhnovets AI, Kaznadzey AD, Gelfand MS, Ozoline ON. Sense and antisense RNA products of the uxuR gene can affect motility and chemotaxis acting independent of the UxuR protein. Front Mol Biosci 2023; 10:1121376. [PMID: 36936992 PMCID: PMC10016265 DOI: 10.3389/fmolb.2023.1121376] [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: 12/11/2022] [Accepted: 02/06/2023] [Indexed: 02/19/2023] Open
Abstract
Small non-coding and antisense RNAs are widespread in all kingdoms of life, however, the diversity of their functions in bacteria is largely unknown. Here, we study RNAs synthesised from divergent promoters located in the 3'-end of the uxuR gene, encoding transcription factor regulating hexuronate metabolism in Escherichia coli. These overlapping promoters were predicted in silico with rather high scores, effectively bound RNA polymerase in vitro and in vivo and were capable of initiating transcription in sense and antisense directions. The genome-wide correlation between in silico promoter scores and RNA polymerase binding in vitro and in vivo was higher for promoters located on the antisense strands of the genes, however, sense promoters within the uxuR gene were more active. Both regulatory RNAs synthesised from the divergent promoters inhibited expression of genes associated with the E. coli motility and chemotaxis independent of a carbon source on which bacteria had been grown. Direct effects of these RNAs were confirmed for the fliA gene encoding σ28 subunit of RNA polymerase. In addition to intracellular sRNAs, promoters located within the uxuR gene could initiate synthesis of transcripts found in the fraction of RNAs secreted in the extracellular medium. Their profile was also carbon-independent suggesting that intragenic uxuR transcripts have a specific regulatory role not directly related to the function of the protein in which gene they are encoded.
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Affiliation(s)
- Maria N. Tutukina
- Center for Molecular and Cellular Biology, Skolkovo Institute of Science and Technology, Moscow, Russia
- Lab of Functional Genomics and Cellular Stress, Institute of Cell Biophysics RAS, FRC PRCBR, Pushchino, Russia
- RTC “Bioinformatics”, A. A. Kharkevich Institute for Information Transmission Problems RAS, Moscow, Russia
- *Correspondence: Maria N. Tutukina, , Olga N. Ozoline,
| | - Artemiy I. Dakhnovets
- Center for Molecular and Cellular Biology, Skolkovo Institute of Science and Technology, Moscow, Russia
- Department of Biotechnology, M. V. Lomonosov Moscow State University, Moscow, Russia
| | - Anna D. Kaznadzey
- RTC “Bioinformatics”, A. A. Kharkevich Institute for Information Transmission Problems RAS, Moscow, Russia
| | - Mikhail S. Gelfand
- Center for Molecular and Cellular Biology, Skolkovo Institute of Science and Technology, Moscow, Russia
- RTC “Bioinformatics”, A. A. Kharkevich Institute for Information Transmission Problems RAS, Moscow, Russia
| | - Olga N. Ozoline
- Lab of Functional Genomics and Cellular Stress, Institute of Cell Biophysics RAS, FRC PRCBR, Pushchino, Russia
- *Correspondence: Maria N. Tutukina, , Olga N. Ozoline,
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3
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Micallef SA, Han S, Martinez L. Tomato Cultivar Nyagous Fruit Surface Metabolite Changes during Ripening Affect Salmonella Newport. J Food Prot 2022; 85:1604-1613. [PMID: 36048925 DOI: 10.4315/jfp-22-160] [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: 05/25/2022] [Accepted: 08/30/2022] [Indexed: 11/11/2022]
Abstract
ABSTRACT Tomatoes are a valuable crop consumed year-round. Ripe fruit is picked for local sale, whereas tomatoes intended for transit may be harvested at late mature green or breaker stages when fruit firmness preserves quality. In this study, we evaluated Solanum lycopersicum cv. BHN602 association with three Salmonella serotypes and S. lycopersicum cv. Nyagous with Salmonella Newport using fruit at two ripeness stages. Counts of Salmonella Javiana and Typhimurium were higher from red ripe fruit surfaces of BHN602, and counts of Salmonella Newport were higher from ripe Nyagous fruit than from mature green fruit (P < 0.05). Aqueous fruit washes containing fruit surface compounds collected from ripe Nyagous fruit supported more Salmonella Newport growth than green fruit washes (P < 0.05). Growth curve analysis showed that between 2 and 6 h, Salmonella Newport grew at a rate of 0.25 log CFU/h in red fruit wash compared with 0.17 log CFU/h in green fruit wash (P < 0.05). The parallel trend in Salmonella interaction between fruit and wash suggested that surface metabolite differences between unripe and ripe fruit affect Salmonella dynamics. Untargeted phytochemical profiling of tomato fruit surface washes with gas chromatography time-of-flight mass spectrometry showed that ripe fruit had threefold-lower amino acid and fourfold-higher sugar (fructose, glucose, and xylose) levels than green fruit. Green fruit had higher levels of lauric, palmitic, margaric, and arachidic acids, whereas red fruit had more capric acid. The phenolics ferulic, chlorogenic, and vanillic acid, as well as tyrosol, also decreased with ripening. Although limitations of this study preclude conclusions on how specific compounds affect Salmonella, our study highlights the complexity of the plant niche for foodborne pathogens and the importance of understanding the metabolite landscape Salmonella encounters on fresh produce. Fruit surface phytochemical profiling generated testable hypotheses for future studies exploring the differential Salmonella interactions with tomato varieties and fruit at various ripeness stages. HIGHLIGHTS
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Affiliation(s)
- Shirley A Micallef
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742, USA.,Center for Food Safety and Security Systems, University of Maryland, College Park, Maryland 20742, USA
| | - Sanghyun Han
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742, USA
| | - Louisa Martinez
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742, USA
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4
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Jiang WX, Li PY, Chen XL, Zhang YS, Wang JP, Wang YJ, Sheng Q, Sun ZZ, Qin QL, Ren XB, Wang P, Song XY, Chen Y, Zhang YZ. A pathway for chitin oxidation in marine bacteria. Nat Commun 2022; 13:5899. [PMID: 36202810 PMCID: PMC9537276 DOI: 10.1038/s41467-022-33566-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 09/22/2022] [Indexed: 11/09/2022] Open
Abstract
Oxidative degradation of chitin, initiated by lytic polysaccharide monooxygenases (LPMOs), contributes to microbial bioconversion of crystalline chitin, the second most abundant biopolymer in nature. However, our knowledge of oxidative chitin utilization pathways, beyond LPMOs, is very limited. Here, we describe a complete pathway for oxidative chitin degradation and its regulation in a marine bacterium, Pseudoalteromonas prydzensis. The pathway starts with LPMO-mediated extracellular breakdown of chitin into C1-oxidized chitooligosaccharides, which carry a terminal 2-(acetylamino)-2-deoxy-D-gluconic acid (GlcNAc1A). Transmembrane transport of oxidized chitooligosaccharides is followed by their hydrolysis in the periplasm, releasing GlcNAc1A, which is catabolized in the cytoplasm. This pathway differs from the known hydrolytic chitin utilization pathway in enzymes, transporters and regulators. In particular, GlcNAc1A is converted to 2-keto-3-deoxygluconate 6-phosphate, acetate and NH3 via a series of reactions resembling the degradation of D-amino acids rather than other monosaccharides. Furthermore, genomic and metagenomic analyses suggest that the chitin oxidative utilization pathway may be prevalent in marine Gammaproteobacteria.
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Affiliation(s)
- Wen-Xin Jiang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China.,College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Ping-Yi Li
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China. .,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China.
| | - Xiu-Lan Chen
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Yi-Shuo Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Jing-Ping Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yan-Jun Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Qi Sheng
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Zhong-Zhi Sun
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Qi-Long Qin
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Xue-Bing Ren
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Peng Wang
- College of Marine Life Sciences, Ocean University of China, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Xiao-Yan Song
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yin Chen
- College of Marine Life Sciences, Ocean University of China, Qingdao, China.,School of Life Sciences, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Yu-Zhong Zhang
- College of Marine Life Sciences, Ocean University of China, Qingdao, China. .,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China. .,Marine Biotechnology Research Center, State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China.
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5
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Bessonova TA, Fando MS, Kostareva OS, Tutukina MN, Ozoline ON, Gelfand MS, Nikulin AD, Tishchenko SV. Differential Impact of Hexuronate Regulators ExuR and UxuR on the Escherichia coli Proteome. Int J Mol Sci 2022; 23:ijms23158379. [PMID: 35955512 PMCID: PMC9369180 DOI: 10.3390/ijms23158379] [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: 06/27/2022] [Revised: 07/19/2022] [Accepted: 07/26/2022] [Indexed: 11/16/2022] Open
Abstract
ExuR and UxuR are paralogous proteins belonging to the GntR family of transcriptional regulators. Both are known to control hexuronic acid metabolism in a variety of Gammaproteobacteria but the relative impact of each of them is still unclear. Here, we apply 2D difference electrophoresis followed by mass-spectrometry to characterise the changes in the Escherichia coli proteome in response to a uxuR or exuR deletion. Our data clearly show that the effects are different: deletion of uxuR resulted in strongly enhanced expression of D-mannonate dehydratase UxuA and flagellar protein FliC, and in a reduced amount of outer membrane porin OmpF, while the absence of ExuR did not significantly alter the spectrum of detected proteins. Consequently, the physiological roles of proteins predicted as homologs seem to be far from identical. Effects of uxuR deletion were largely dependent on the cultivation conditions: during growth with glucose, UxuA and FliC were dramatically altered, while during growth with glucuronate, activation of both was not so prominent. During the growth with glucose, maximal activation was detected for FliC. This was further confirmed by expression analysis and physiological tests, thus suggesting the involvement of UxuR in the regulation of bacterial motility and biofilm formation.
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Affiliation(s)
- Tatiana A. Bessonova
- Institute of Cell Biophysics, Russian Academy of Sciences, PSCBR RAS, Institutskaya, 3, Pushchino 142290, Russia; (T.A.B.); (O.N.O.)
| | - Maria S. Fando
- Institute of Protein Research, Russian Academy of Sciences, Institutskaya, 4, Pushchino 142290, Russia; (M.S.F.); (O.S.K.); (A.D.N.); (S.V.T.)
| | - Olga S. Kostareva
- Institute of Protein Research, Russian Academy of Sciences, Institutskaya, 4, Pushchino 142290, Russia; (M.S.F.); (O.S.K.); (A.D.N.); (S.V.T.)
| | - Maria N. Tutukina
- Institute of Cell Biophysics, Russian Academy of Sciences, PSCBR RAS, Institutskaya, 3, Pushchino 142290, Russia; (T.A.B.); (O.N.O.)
- Skolkovo Institute of Science and Technology, Bolshoy Boulevard 30 Build 1, Moscow 121205, Russia;
- Institute for Information Transmission Problems, Russian Academy of Sciences, Bolshoy Karetny Per 19 Build 1, Moscow 127051, Russia
- Correspondence:
| | - Olga N. Ozoline
- Institute of Cell Biophysics, Russian Academy of Sciences, PSCBR RAS, Institutskaya, 3, Pushchino 142290, Russia; (T.A.B.); (O.N.O.)
| | - Mikhail S. Gelfand
- Skolkovo Institute of Science and Technology, Bolshoy Boulevard 30 Build 1, Moscow 121205, Russia;
- Institute for Information Transmission Problems, Russian Academy of Sciences, Bolshoy Karetny Per 19 Build 1, Moscow 127051, Russia
| | - Alexey D. Nikulin
- Institute of Protein Research, Russian Academy of Sciences, Institutskaya, 4, Pushchino 142290, Russia; (M.S.F.); (O.S.K.); (A.D.N.); (S.V.T.)
| | - Svetlana V. Tishchenko
- Institute of Protein Research, Russian Academy of Sciences, Institutskaya, 4, Pushchino 142290, Russia; (M.S.F.); (O.S.K.); (A.D.N.); (S.V.T.)
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6
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Tishchenko SV, Mikhailina AO, Lekontseva NV, Stolboushkina EA, Nikonova EY, Nikonov OS, Nikulin AD. Structural Investigations of RNA–Protein Complexes in Post-Ribosomal Era. CRYSTALLOGR REP+ 2021. [DOI: 10.1134/s1063774521050217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Abstract
Structural studies of RNA–protein complexes are important for understanding many molecular mechanisms occurring in cells (e.g., regulation of protein synthesis and RNA-chaperone activity of proteins). Various objects investigated at the Institute of Protein Research of the Russian Academy of Sciences are considered. Based on the analysis of the structures of the complexes of the ribosomal protein L1 with specific regions on both mRNA and rRNA, the principles of regulation of the translation of the mRNA of its own operon are presented. The studies of the heterotrimeric translation initiation factor IF2 of archaea and eukaryotes are described, and the data on the interaction of glycyl-tRNA-synthetase with viral IRES are reported. The results of studying the interaction of RNA molecules with one of functionally important sites of the Hfq protein are presented, and the differences in the RNA-binding properties of the Hfq and archaeal Lsm proteins are revealed.
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7
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Burin R, Shah DH. Global transcriptional profiling of tyramine and d-glucuronic acid catabolism in Salmonella. Int J Med Microbiol 2020; 310:151452. [PMID: 33091748 DOI: 10.1016/j.ijmm.2020.151452] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 08/13/2020] [Accepted: 09/25/2020] [Indexed: 11/17/2022] Open
Abstract
Salmonella has evolved various metabolic pathways to scavenge energy from the metabolic byproducts of the host gut microbiota, however, the precise metabolic byproducts and pathways utilized by Salmonella remain elusive. Previously we reported that Salmonella can proliferate by deriving energy from two metabolites that naturally occur in the host as gut microbial metabolic byproducts, namely, tyramine (TYR, an aromatic amine) and d-glucuronic acid (DGA, a hexuronic acid). Salmonella Pathogenicity Island 13 (SPI-13) plays a critical role in the ability of Salmonella to derive energy from TYR and DGA, however the catabolic pathways of these two micronutrients in Salmonella are poorly defined. The objective of this study was to identify the specific genetic components and construct the regulatory circuits for the TYR and DGA catabolic pathways in Salmonella. To accomplish this, we employed TYR and DGA-induced global transcriptional profiling and gene functional network analysis approaches. We report that TYR induced differential expression of 319 genes (172 up-regulated and 157 down-regulated) when Salmonella was grown in the presence of TYR as a sole energy source. These included the genes originally predicted to be involved in the classical TYR catabolic pathway. TYR also induced expression of majority of genes involved in the acetaldehyde degradation pathway and aided identification of a few new genes that are likely involved in alternative pathway for TYR catabolism. In contrast, DGA induced differential expression of 71 genes (58 up-regulated and 13 down-regulated) when Salmonella was grown in the presence of DGA as a sole energy source. These included the genes originally predicted to be involved in the classical pathway and a few new genes likely involved in the alternative pathway for DGA catabolism. Interestingly, DGA also induced expression of SPI-2 T3SS, suggesting that DGA may also influence nutritional virulence of Salmonella. In summary, this is the first report describing the global transcriptional profiling of TYR and DGA catabolic pathways of Salmonella. This study will contribute to the better understanding of the role of TYR and DGA in metabolic adaptation and virulence of Salmonella.
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Affiliation(s)
- Raquel Burin
- Department of Veterinary Microbiology and Pathology, United States
| | - Devendra H Shah
- Department of Veterinary Microbiology and Pathology, United States; Paul Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164-7040, United States.
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8
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Jimenez AG, Ellermann M, Abbott W, Sperandio V. Diet-derived galacturonic acid regulates virulence and intestinal colonization in enterohaemorrhagic Escherichia coli and Citrobacter rodentium. Nat Microbiol 2019; 5:368-378. [PMID: 31873206 PMCID: PMC6992478 DOI: 10.1038/s41564-019-0641-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 11/11/2019] [Indexed: 12/21/2022]
Abstract
Enteric pathogens sense the complex chemistry within the gastrointestinal (GI) tract to efficiently compete with the resident microbiota and establish a colonization niche. Here we show that enterohemorrhagic E. coli (EHEC), and its surrogate murine infection model Citrobacter rodentium, sense galacturonic-acid to initiate a multi-layered program towards successful mammalian infection. Galacturonic-acid utilization as a carbon source aids the initial pathogen expansion. The main source of galacturonic-acid is dietary pectin, which is broken into galacturonic-acid by the prominent member of the microbiota, Bacteroides thetaiotamicron (Bt). This regulation occurs through the ExuR transcription factor. However, galacturonic-acid is also sensed as a signal through ExuR to modulate the expression of the genes encoding a molecular syringe known as a type three secretion system (T3SS) leading to infectious colitis and inflammation. Galacturonic-acid moonlights as a nutrient and a signal directing the exquisite microbiota-pathogen relationships within the GI tract. Importantly, this work highlights that differential dietary sugar availability impacts the relationship between the microbiota and enteric pathogens, as well as disease outcomes.
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Affiliation(s)
- Angel G Jimenez
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Melissa Ellermann
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Wade Abbott
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, Alberta, Canada.,Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Vanessa Sperandio
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA. .,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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9
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Wallner A, King E, Ngonkeu ELM, Moulin L, Béna G. Genomic analyses of Burkholderia cenocepacia reveal multiple species with differential host-adaptation to plants and humans. BMC Genomics 2019; 20:803. [PMID: 31684866 PMCID: PMC6829993 DOI: 10.1186/s12864-019-6186-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 10/15/2019] [Indexed: 12/17/2022] Open
Abstract
Background Burkholderia cenocepacia is a human opportunistic pathogen causing devastating symptoms in patients suffering from immunodeficiency and cystic fibrosis. Out of the 303 B. cenocepacia strains with available genomes, the large majority were isolated from a clinical context. However, several isolates originate from other environmental sources ranging from aerosols to plant endosphere. Plants can represent reservoirs for human infections as some pathogens can survive and sometimes proliferate in the rhizosphere. We therefore investigated if B. cenocepacia had the same potential. Results We selected genome sequences from 31 different strains, representative of the diversity of ecological niches of B. cenocepacia, and conducted comparative genomic analyses in the aim of finding specific niche or host-related genetic determinants. Phylogenetic analyses and whole genome average nucleotide identity suggest that strains, registered as B. cenocepacia, belong to at least two different species. Core-genome analyses show that the clade enriched in environmental isolates lacks multiple key virulence factors, which are conserved in the sister clade where most clinical isolates fall, including the highly virulent ET12 lineage. Similarly, several plant associated genes display an opposite distribution between the two clades. Finally, we suggest that B. cenocepacia underwent a host jump from plants/environment to animals, as supported by the phylogenetic analysis. We eventually propose a name for the new species that lacks several genetic traits involved in human virulence. Conclusion Regardless of the method used, our studies resulted in a disunited perspective of the B. cenocepacia species. Strains currently affiliated to this taxon belong to at least two distinct species, one having lost several determining animal virulence factors.
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Affiliation(s)
- Adrian Wallner
- IRD, CIRAD, University of Montpellier, IPME; 911 avenue Agropolis, BP 64501, 34394, Montpellier, France
| | - Eoghan King
- IRD, CIRAD, University of Montpellier, IPME; 911 avenue Agropolis, BP 64501, 34394, Montpellier, France
| | - Eddy L M Ngonkeu
- Institute of Agronomic Research for Development (IRAD), PO Box 2123, Yaoundé, Cameroon
| | - Lionel Moulin
- IRD, CIRAD, University of Montpellier, IPME; 911 avenue Agropolis, BP 64501, 34394, Montpellier, France
| | - Gilles Béna
- IRD, CIRAD, University of Montpellier, IPME; 911 avenue Agropolis, BP 64501, 34394, Montpellier, France.
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10
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Shimada T, Ogasawara H, Ishihama A. Single-target regulators form a minor group of transcription factors in Escherichia coli K-12. Nucleic Acids Res 2019. [PMID: 29529243 PMCID: PMC5934670 DOI: 10.1093/nar/gky138] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The identification of regulatory targets of all TFs is critical for understanding the entire network of the genome regulation. The lac regulon of Escherichia coli K-12 W3110 is composed of the lacZYA operon and its repressor lacI gene, and has long been recognized as the seminal model of transcription regulation in bacteria with only one highly preferred target. After the Genomic SELEX screening in vitro of more than 200 transcription factors (TFs) from E. coli K-12, however, we found that most TFs regulate multiple target genes. With respect to the number of regulatory targets, a total of these 200 E. coli TFs form a hierarchy ranging from a single target to as many as 1000 targets. Here we focus a total of 13 single-target TFs, 9 known TFs (BetI, KdpE, LacI, MarR, NanR, RpiR, TorR, UlaR and UxuR) and 4 uncharacterized TFs (YagI, YbaO, YbiH and YeaM), altogether forming only a minor group of TFs in E. coli. These single-target TFs were classified into three groups based on their functional regulation.
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Affiliation(s)
- Tomohiro Shimada
- Meiji University, School of Agriculture, Kawasaki, Kanagawa 214-8571, Japan
| | - Hiroshi Ogasawara
- Shinshu University, Research Center for Supports to Advanced Science, Division of Gene Research, Ueda, Nagano 386-8567, Japan.,Shinshu University, Research Center for Fungal and Microbial Dynamism, Kamiina, Nagano 399-4598, Japan
| | - Akira Ishihama
- Hosei University, Micro-Nano Technology Research Center, Koganei, Tokyo 184-8584, Japan
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11
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Regmi A, Boyd EF. Carbohydrate metabolic systems present on genomic islands are lost and gained in Vibrio parahaemolyticus. BMC Microbiol 2019; 19:112. [PMID: 31133029 PMCID: PMC6537148 DOI: 10.1186/s12866-019-1487-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Accepted: 05/10/2019] [Indexed: 12/16/2022] Open
Abstract
Background Utilizing unique carbohydrates or utilizing them more efficiently help bacteria expand and colonize new niches. Horizontal gene transfer (HGT) of catabolic systems is a powerful mechanism by which bacteria can acquire new phenotypic traits that can increase survival and fitness in different niches. In this work, we examined carbon catabolism diversity among Vibrio parahaemolyticus, a marine species that is also an important human and fish pathogen. Results Phenotypic differences in carbon utilization between Vibrio parahaemolyticus strains lead us to examine genotypic differences in this species and the family Vibrionaceae in general. Bioinformatics analysis showed that the ability to utilize d-galactose was present in all V. parahaemolyticus but at least two distinct transporters were present; a major facilitator superfamily (MFS) transporter and a sodium/galactose transporter (SGLT). Growth and genetic analyses demonstrated that SGLT was a more efficient transporter of d-galactose and was the predominant type among strains. Phylogenetic analysis showed that d-galactose gene galM was acquired multiples times within the family Vibrionaceae and was transferred between distantly related species. The ability to utilize d-gluconate was universal within the species. Deletion of eda (VP0065), which encodes aldolase, a key enzyme in the Entner-Doudoroff (ED) pathway, reached a similar biomass to wild type when grown on d-gluconate as a sole carbon source. Two additional eda genes were identified, VPA1708 (eda2) associated with a d-glucuronate cluster and VPA0083 (eda3) that clustered with an oligogalacturonide (OGA) metabolism cluster. EDA2 and EDA3 were variably distributed among the species. A metabolic island was identified that contained citrate fermentation, l-rhamnose and OGA metabolism clusters as well as a CRISPR-Cas system. Phylogenetic analysis showed that CitF and RhaA had a limited distribution among V. parahaemolyticus, and RhaA was acquired at least three times. Within V. parahaemolyticus, two different regions contained the gene for L-arabinose catabolism and most strains had the ability to catabolism this sugar. Conclusion Our data suggest that horizontal transfer of metabolic systems among Vibrionaceae is an important source of metabolic diversity. This work identified four EDA homologues suggesting that the ED pathway plays a significant role in metabolism. We describe previously uncharacterized metabolism islands that were hotspots for the gain and loss of functional modules likely mediated by transposons. Electronic supplementary material The online version of this article (10.1186/s12866-019-1487-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Abish Regmi
- Department of Biological Sciences, University of Delaware, 341 Wolf Hall, Newark, DE, 19716, USA
| | - Ethna Fidelma Boyd
- Department of Biological Sciences, University of Delaware, 341 Wolf Hall, Newark, DE, 19716, USA.
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Purtov YA, Tutukina MN, Nikulin AD, Ozoline ON. The Topology of the Contacts of Potential Ligands for the UxuR Transcription Factor of Escherichia coli as Revealed by Flexible Molecular Docking. Biophysics (Nagoya-shi) 2019. [DOI: 10.1134/s0006350919010160] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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13
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Bessonova TA, Lekontseva NV, Shvyreva US, Nikulin AD, Tutukina MN, Ozoline ON. Overproduction and purification of the Escherichia coli transcription factors "toxic" to a bacterial cell. Protein Expr Purif 2019; 161:70-77. [PMID: 31054315 DOI: 10.1016/j.pep.2019.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/25/2019] [Accepted: 05/01/2019] [Indexed: 11/28/2022]
Abstract
Transcription factors play a crucial role in control of life of a bacterial cell, working as switchers to a different life style or pathogenicity. To reconstruct the network of regulatory events taking place in changing growth conditions, we need to know regulons of as many transcription factors as possible, and motifs recognized by them. Experimentally this can be attained via ChIP-seq in vivo, SELEX and DNAse I footprinting in vitro. All these approaches require large amounts of purified proteins. However, overproduction of transcription factors leading to their extensive binding to the regulatory elements on the DNA make them toxic to a bacterial cell thus significantly complicating production of a soluble protein. Here, on the example of three regulators from Escherichia coli, UxuR, ExuR, and LeuO, we show that stable production of toxic transcription factors in a soluble fraction can be significantly enhanced by holding the expression of a recombinant protein back at the early stages of bacterial growth. This can be achieved by cloning genes together with their regulatory regions containing repressor sites, with subsequent growth in a very rich media where activity of excessive regulators is not crucial, followed by induction with a very low concentration of an inducer. Schemes of further purification of these proteins were developed, and functional activity was confirmed.
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Affiliation(s)
- Tatiana A Bessonova
- Institute of Cell Biophysics of RAS, Pushchino, Moscow region, 142290, Russia; Institute of Protein Research RAS, Pushchino, Moscow region, 142290, Russia; Lomonosov Moscow State University, Moscow, 119991, Russia.
| | | | - Uliana S Shvyreva
- Institute of Cell Biophysics of RAS, Pushchino, Moscow region, 142290, Russia; Institute of Protein Research RAS, Pushchino, Moscow region, 142290, Russia
| | - Alexey D Nikulin
- Institute of Protein Research RAS, Pushchino, Moscow region, 142290, Russia
| | - Maria N Tutukina
- Institute of Cell Biophysics of RAS, Pushchino, Moscow region, 142290, Russia; Kharkevich Institute for Information Transmission Problems RAS, Moscow, 127051, Russia
| | - Olga N Ozoline
- Institute of Cell Biophysics of RAS, Pushchino, Moscow region, 142290, Russia
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14
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How Bioinformatic Tools Guide Experiments To Resolve the Chaos of Apparently Unlimited Metabolic Variation. J Bacteriol 2018; 201:JB.00628-18. [PMID: 30373753 DOI: 10.1128/jb.00628-18] [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: 10/10/2018] [Accepted: 10/23/2018] [Indexed: 11/20/2022] Open
Abstract
Hexuronic acids, oxidation products of common sugars, are widespread in eukaryotic cells. Galacturonic acid is the main carbohydrate component of pectin found in plant cell walls and glucuronic acid is a component of proteoglycans in animals. However, despite their importance as carbohydrate substrates, metabolism of hexuronic acids has long remained a poorly studied corner of the bacterial metabolic map. In the current issue of Journal of Bacteriology, Bouvier and coworkers present a detailed analysis of genes involved in hexuronate utilization in various proteobacteria and report the verification of their bioinformatics predictions by carefully designed experiments (J. T. Bouvier et al., J Bacteriol 201:e00431-18, 2019, https://doi.org/10.1128/JB.00431-18). This study provides a solid basis for understanding hexuronate metabolism and its regulation in other bacterial phyla.
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15
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Novel Metabolic Pathways and Regulons for Hexuronate Utilization in Proteobacteria. J Bacteriol 2018; 201:JB.00431-18. [PMID: 30249705 DOI: 10.1128/jb.00431-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 09/19/2018] [Indexed: 02/07/2023] Open
Abstract
We used comparative genomics to reconstruct d-galacturonic and d-glucuronic acid catabolic pathways and associated transcriptional regulons involving the tripartite ATP-independent periplasmic (TRAP) family transporters that bind hexuronates in proteobacteria. The reconstructed catabolic network involves novel transcription factors, catabolic enzymes, and transporters for utilization of both hexuronates and aldarates (d-glucarate and meso-galactarate). The reconstructed regulons for a novel GntR family transcription factor, GguR, include the majority of hexuronate/aldarate utilization genes in 47 species from the Burkholderiaceae, Comamonadaceae, Halomonadaceae, and Pseudomonadaceae families. GudR, GulR, and UdhR are additional local regulators of some hexuronate/aldarate utilization genes in some of the above-mentioned organisms. The predicted DNA binding motifs of GguR and GudR regulators from Ralstonia pickettii and Polaromonas were validated by in vitro binding assays. Genes from the GulR- and GguR-controlled loci were differentially expressed in R. pickettii grown on hexuronates and aldarates. By a combination of bioinformatics and experimental techniques we identified a novel variant of the oxidative pathway for hexuronate utilization, including two previously uncharacterized subfamilies of lactone hydrolases (UxuL and UxuF). The genomic context of respective genes and reconstruction of associated pathways suggest that both enzymes catalyze the conversion of d-galactaro- and d-glucaro-1,5-lactones to the ring-opened aldarates. The activities of the purified recombinant enzymes, UxuL and UxuF, from four proteobacterial species were directly confirmed and kinetically characterized. The inferred novel aldarate-specific transporter from the tripartite tricarboxylate transporter (TTT) family transporter TctC was confirmed to bind d-glucarate in vitro This study expands our knowledge of bacterial carbohydrate catabolic pathways by identifying novel families of catabolic enzymes, transcriptional regulators, and transporters.IMPORTANCE Hexuronate catabolic pathways and their transcriptional networks are highly variable among different bacteria. We identified novel transcriptional regulators that control the hexuronate and aldarate utilization genes in four families of proteobacteria. By regulon reconstruction and genome context analysis we identified several novel components of the common hexuronate/aldarate utilization pathways, including novel uptake transporters and catabolic enzymes. Two novel families of lactonases involved in the oxidative pathway of hexuronate catabolism were characterized. Novel transcriptional regulons were validated via in vitro binding assays and gene expression studies with Polaromonas and Ralstonia species. The reconstructed catabolic pathways are interconnected with each other metabolically and coregulated via the GguR regulons in proteobacteria.
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Elder JR, Paul NC, Burin R, Guard J, Shah DH. Genomic organization and role of SPI-13 in nutritional fitness of Salmonella. Int J Med Microbiol 2018; 308:1043-1052. [PMID: 30466554 DOI: 10.1016/j.ijmm.2018.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 09/21/2018] [Accepted: 10/10/2018] [Indexed: 02/07/2023] Open
Abstract
Salmonella pathogenicity island 13 (SPI-13) contributes to the virulence of Salmonella. The majority of the SPI-13 genes encode proteins putatively involved in bacterial metabolism, however, their functions largely remain uncharacterized. It is currently unknown if SPI-13 contributes to metabolic fitness of Salmonella and, if so, what are the metabolic substrates for the protein encoded by genes within SPI-13. We employed Phenotype Microarray (Biolog, USA) to compare the metabolic properties of SPI-13 deficient mutant (ΔSPI-13) and the WT parent strain of non-typhoidal Salmonella enterica sub sp. enterica serovar Enteritidis (S. Enteritidis). The results of Phenotype Microarray revealed that SPI-13 is required for efficient utilization of two micronutrients, namely, d-glucuronic acid (DGA) and tyramine (TYR), as sole sources of carbon and/or nitrogen. By systematic deletion of the individual gene(s), we identified specific genes within SPI-13 that are required for efficient utilization of DGA (SEN2977-80) and TYR (SEN2967 and SEN2971-72) as sole nutrient sources. The results show that SPI-13 mediated DGA and TYR metabolic pathways afford nutritional fitness to S. Enteritidis. Comparative genomics analysis of the SPI-13 locus from 247 Salmonella strains belonging to 57 different serovars revealed that SPI-13 genes specifically involved in the metabolism of DGA and TYR are highly conserved in Salmonella enterica. Because DGA and TYR are naturally present as metabolic byproducts in the gastrointestinal tract and other host tissues, we propose a metabolic model that shows that the role of SPI-13 mediated DGA and TYR metabolism in the nutritional fitness of Salmonella is likely linked to nutritional virulence of this pathogen.
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Affiliation(s)
- Jacob R Elder
- Department of Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, Washington, 99164-7040, USA
| | - Narayan C Paul
- Department of Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, Washington, 99164-7040, USA
| | - Raquel Burin
- Department of Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, Washington, 99164-7040, USA
| | - Jean Guard
- Egg Quality and Safety Research Unit, Agriculture Research Service, United StatesDepartment of Agriculture, Athens, GA, 30605, USA
| | - Devendra H Shah
- Department of Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, Washington, 99164-7040, USA; Paul Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, 99164-7040, USA.
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17
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Genome Analysis of Endomicrobium proavitum Suggests Loss and Gain of Relevant Functions during the Evolution of Intracellular Symbionts. Appl Environ Microbiol 2017. [PMID: 28646115 DOI: 10.1128/aem.00656-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial endosymbionts of eukaryotes show progressive genome erosion, but detailed investigations of the evolutionary processes involved in the transition to an intracellular lifestyle are generally hampered by the lack of extant free-living lineages. Here, we characterize the genome of the recently isolated, free-living Endomicrobium proavitum, the second member of the Elusimicrobia phylum brought into pure culture, and compare it to the closely related "Candidatus Endomicrobium trichonymphae" strain Rs-D17, a previously described but uncultured endosymbiont of termite gut flagellates. A reconstruction of the metabolic pathways of Endomicrobium proavitum matched the fermentation products formed in pure culture and underscored its restriction to glucose as the substrate. However, several pathways present in the free-living strain, e.g., for the uptake and activation of glucose and its subsequent fermentation, ammonium assimilation, and outer membrane biogenesis, were absent or disrupted in the endosymbiont, probably lost during the massive genome rearrangements that occurred during symbiogenesis. While the majority of the genes in strain Rs-D17 have orthologs in Endomicrobium proavitum, the endosymbiont also possesses a number of functions that are absent from the free-living strain and may represent adaptations to the intracellular lifestyle. Phylogenetic analysis revealed that the genes encoding glucose 6-phosphate and amino acid transporters, acetaldehyde/alcohol dehydrogenase, and the pathways of glucuronic acid catabolism and thiamine pyrophosphate biosynthesis were either acquired by horizontal gene transfer or may represent ancestral traits that were lost in the free-living strain. The polyphyletic origin of Endomicrobia in different flagellate hosts makes them excellent models for future studies of convergent and parallel evolution during symbiogenesis.IMPORTANCE The isolation of a free-living relative of intracellular symbionts provides the rare opportunity to identify the evolutionary processes that occur in the course of symbiogenesis. Our study documents that the genome of "Candidatus Endomicrobium trichonymphae," which represents a clade of endosymbionts that have coevolved with termite gut flagellates for more than 40 million years, is not simply a subset of the genes present in Endomicrobium proavitum, a member of the ancestral, free-living lineage. Rather, comparative genomics revealed that the endosymbionts possess several relevant functions that were either prerequisites for colonization of the intracellular habitat or might have served to compensate for genes losses that occurred during genome erosion. Some gene sets found only in the endosymbiont were apparently acquired by horizontal transfer from other gut bacteria, which suggests that the intracellular bacteria of flagellates are not entirely cut off from gene flow.
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18
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Tang K, Lin Y, Han Y, Jiao N. Characterization of Potential Polysaccharide Utilization Systems in the Marine Bacteroidetes Gramella Flava JLT2011 Using a Multi-Omics Approach. Front Microbiol 2017; 8:220. [PMID: 28261179 PMCID: PMC5306329 DOI: 10.3389/fmicb.2017.00220] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 01/31/2017] [Indexed: 01/26/2023] Open
Abstract
Members of phylum Bacteroidetes are distributed across diverse marine niches and Flavobacteria is often the predominant bacterial class decomposing algae-derived polysaccharides. Here, we report the complete genome of Gramella flava JLT2011 (Flavobacteria) isolated from surface water of the southeastern Pacific. A remarkable genomic feature is that the number of glycoside hydrolase (GH) genes in the genome of G. flava JLT2011 is more than 2-fold higher than that of other Gramella species. The functional profiles of the GHs suggest extensive variation in Gramella species. Growth experiments revealed that G. flava JLT2011 has the ability to utilize a wide range of polysaccharides for growth such as xylan and homogalacturonan in pectin. Nearly half of all GH genes were located on the multi-gene polysaccharide utilization loci (PUL) or PUL-like systems in G. flava JLT2011. This species was also found to harbor the two xylan PULs and a pectin PUL, respectively. Gene expression data indicated that more GHs and sugar-specific outer-membrane susC-susD systems were found in the presence of xylan than in the presence of pectin, suggesting a different strategy for heteropolymeric xylan and homoglacturonan utilization. Multi-omics data (transcriptomics, proteomics, and metabolomics) indicated that xylan PULs and pectin PUL are respectively involved in the catabolism of their corresponding polysaccharides. This work presents a comparison of polysaccharide decomposition within a genus and expands current knowledge on the diversity and function of PULs in marine Bacteroidetes, thereby deepening our understanding of their ecological role in polysaccharide remineralization in the marine system.
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Affiliation(s)
- Kai Tang
- State Key Laboratory for Marine Environmental Science, Institute of Marine Microbes and Ecospheres, Xiamen University Xiamen, China
| | - Yingfan Lin
- State Key Laboratory for Marine Environmental Science, Institute of Marine Microbes and Ecospheres, Xiamen University Xiamen, China
| | - Yu Han
- State Key Laboratory for Marine Environmental Science, Institute of Marine Microbes and Ecospheres, Xiamen University Xiamen, China
| | - Nianzhi Jiao
- State Key Laboratory for Marine Environmental Science, Institute of Marine Microbes and Ecospheres, Xiamen University Xiamen, China
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19
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Tsoy OV, Ravcheev DA, Čuklina J, Gelfand MS. Nitrogen Fixation and Molecular Oxygen: Comparative Genomic Reconstruction of Transcription Regulation in Alphaproteobacteria. Front Microbiol 2016; 7:1343. [PMID: 27617010 PMCID: PMC4999443 DOI: 10.3389/fmicb.2016.01343] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 08/15/2016] [Indexed: 11/13/2022] Open
Abstract
Biological nitrogen fixation plays a crucial role in the nitrogen cycle. An ability to fix atmospheric nitrogen, reducing it to ammonium, was described for multiple species of Bacteria and Archaea. The transcriptional regulatory network for nitrogen fixation was extensively studied in several representatives of the class Alphaproteobacteria. This regulatory network includes the activator of nitrogen fixation NifA, working in tandem with the alternative sigma-factor RpoN as well as oxygen-responsive regulatory systems, one-component regulators FnrN/FixK and two-component system FixLJ. Here we used a comparative genomics approach for in silico study of the transcriptional regulatory network in 50 genomes of Alphaproteobacteria. We extended the known regulons and proposed the scenario for the evolution of the nitrogen fixation transcriptional network. The reconstructed network substantially expands the existing knowledge of transcriptional regulation in nitrogen-fixing microorganisms and can be used for genetic experiments, metabolic reconstruction, and evolutionary analysis.
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Affiliation(s)
- Olga V Tsoy
- Research and Training Center on Bioinformatics, A.A. Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences Moscow, Russia
| | - Dmitry A Ravcheev
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg Esch-sur-Alzette, Luxembourg
| | - Jelena Čuklina
- Research and Training Center on Bioinformatics, A.A. Kharkevich Institute for Information Transmission Problems, Russian Academy of SciencesMoscow, Russia; Moscow Institute of Physics and TechnologyDolgoprudny, Russia
| | - Mikhail S Gelfand
- Research and Training Center on Bioinformatics, A.A. Kharkevich Institute for Information Transmission Problems, Russian Academy of SciencesMoscow, Russia; Faculty of Bioengineering and Bioinformatics, Moscow State UniversityMoscow, Russia; Skolkovo Institute of Science and TechnologySkolkovo, Russia; Faculty of Computer Science, Higher School of EconomicsMoscow, Russia
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Tutukina MN, Potapova AV, Cole JA, Ozoline ON. Control of hexuronate metabolism in Escherichia coli by the two interdependent regulators, ExuR and UxuR: derepression by heterodimer formation. Microbiology (Reading) 2016; 162:1220-1231. [DOI: 10.1099/mic.0.000297] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Maria N. Tutukina
- Institute of Cell Biophysics of Russian Academy of Sciences, Pushchino, Russia
| | - Anna V. Potapova
- Institute of Cell Biophysics of Russian Academy of Sciences, Pushchino, Russia
| | - Jeffrey A. Cole
- School of Biosciences, University of Birmingham, Birmingham, UK
| | - Olga N. Ozoline
- Institute of Cell Biophysics of Russian Academy of Sciences, Pushchino, Russia
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George AS, Salas González I, Lorca GL, Teplitski M. Contribution of the Salmonella enterica KdgR Regulon to Persistence of the Pathogen in Vegetable Soft Rots. Appl Environ Microbiol 2016; 82:1353-1360. [PMID: 26682862 PMCID: PMC4751823 DOI: 10.1128/aem.03355-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 12/04/2015] [Indexed: 01/13/2023] Open
Abstract
During their colonization of plants, human enteric pathogens, such as Salmonella enterica, are known to benefit from interactions with phytopathogens. At least in part, benefits derived by Salmonella from the association with a soft rot caused by Pectobacterium carotovorum were shown to be dependent on Salmonella KdgR, a regulator of genes involved in the uptake and utilization of carbon sources derived from the degradation of plant polymers. A Salmonella kdgR mutant was more fit in soft rots but not in the lesions caused by Xanthomonas spp. and Pseudomonas spp. Bioinformatic, phenotypic, and gene expression analyses demonstrated that the KdgR regulon included genes involved in uptake and metabolism of molecules resulting from pectin degradation as well as those central to the utilization of a number of other carbon sources. Mutant analyses indicated that the Entner-Doudoroff pathway, in part controlled by KdgR, was critical for the persistence within soft rots and likely was responsible for the kdgR phenotype.
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Affiliation(s)
- Andrée S George
- Soil and Water Science Department, University of Florida-IFAS, Gainesville, Florida, USA
| | - Isai Salas González
- Soil and Water Science Department, University of Florida-IFAS, Gainesville, Florida, USA
| | - Graciela L Lorca
- Microbiology and Cell Science Department, University of Florida-IFAS, Gainesville, Florida, USA
| | - Max Teplitski
- Soil and Water Science Department, University of Florida-IFAS, Gainesville, Florida, USA
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Tutukina MN, Potapova AV, Vlasov PK, Purtov YA, Ozoline ON. Structural modeling of the ExuR and UxuR transcription factors of E. coli: search for the ligands affecting their regulatory properties. J Biomol Struct Dyn 2016; 34:2296-304. [DOI: 10.1080/07391102.2015.1115779] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Maria N. Tutukina
- Institute of Cell Biophysics Russian Academy of Sciences, Institutskaya str., 3, Pushchino, Moscow Region 142290, Russia
| | - Anna V. Potapova
- Institute of Cell Biophysics Russian Academy of Sciences, Institutskaya str., 3, Pushchino, Moscow Region 142290, Russia
| | - Peter K. Vlasov
- Centre for Genomic Regulation (CRG) and Universitat Pompeu Fabra (UPF), C/Dr. Aiguader, 88, Barcelona 08003, Spain
| | - Yuri A. Purtov
- Institute of Cell Biophysics Russian Academy of Sciences, Institutskaya str., 3, Pushchino, Moscow Region 142290, Russia
| | - Olga N. Ozoline
- Institute of Cell Biophysics Russian Academy of Sciences, Institutskaya str., 3, Pushchino, Moscow Region 142290, Russia
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Vetting MW, Al-Obaidi N, Zhao S, San Francisco B, Kim J, Wichelecki DJ, Bouvier JT, Solbiati JO, Vu H, Zhang X, Rodionov DA, Love JD, Hillerich BS, Seidel RD, Quinn RJ, Osterman AL, Cronan JE, Jacobson MP, Gerlt JA, Almo SC. Experimental strategies for functional annotation and metabolism discovery: targeted screening of solute binding proteins and unbiased panning of metabolomes. Biochemistry 2015; 54:909-31. [PMID: 25540822 PMCID: PMC4310620 DOI: 10.1021/bi501388y] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
![]()
The
rate at which genome sequencing data is accruing demands enhanced
methods for functional annotation and metabolism discovery. Solute
binding proteins (SBPs) facilitate the transport of the first reactant
in a metabolic pathway, thereby constraining the regions of chemical
space and the chemistries that must be considered for pathway reconstruction.
We describe high-throughput protein production and differential scanning
fluorimetry platforms, which enabled the screening of 158 SBPs against
a 189 component library specifically tailored for this class of proteins.
Like all screening efforts, this approach is limited by the practical
constraints imposed by construction of the library, i.e., we can study
only those metabolites that are known to exist and which can be made
in sufficient quantities for experimentation. To move beyond these
inherent limitations, we illustrate the promise of crystallographic-
and mass spectrometric-based approaches for the unbiased use of entire
metabolomes as screening libraries. Together, our approaches identified
40 new SBP ligands, generated experiment-based annotations for 2084
SBPs in 71 isofunctional clusters, and defined numerous metabolic
pathways, including novel catabolic pathways for the utilization of
ethanolamine as sole nitrogen source and the use of d-Ala-d-Ala as sole carbon source. These efforts begin to define an
integrated strategy for realizing the full value of amassing genome
sequence data.
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Affiliation(s)
- Matthew W Vetting
- Department of Biochemistry, Albert Einstein College of Medicine , Bronx, New York 10461, United States
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Ravcheev DA, Khoroshkin MS, Laikova ON, Tsoy OV, Sernova NV, Petrova SA, Rakhmaninova AB, Novichkov PS, Gelfand MS, Rodionov DA. Comparative genomics and evolution of regulons of the LacI-family transcription factors. Front Microbiol 2014; 5:294. [PMID: 24966856 PMCID: PMC4052901 DOI: 10.3389/fmicb.2014.00294] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2014] [Accepted: 05/28/2014] [Indexed: 12/31/2022] Open
Abstract
DNA-binding transcription factors (TFs) are essential components of transcriptional regulatory networks in bacteria. LacI-family TFs (LacI-TFs) are broadly distributed among certain lineages of bacteria. The majority of characterized LacI-TFs sense sugar effectors and regulate carbohydrate utilization genes. The comparative genomics approaches enable in silico identification of TF-binding sites and regulon reconstruction. To study the function and evolution of LacI-TFs, we performed genomics-based reconstruction and comparative analysis of their regulons. For over 1300 LacI-TFs from over 270 bacterial genomes, we predicted their cognate DNA-binding motifs and identified target genes. Using the genome context and metabolic subsystem analyses of reconstructed regulons, we tentatively assigned functional roles and predicted candidate effectors for 78 and 67% of the analyzed LacI-TFs, respectively. Nearly 90% of the studied LacI-TFs are local regulators of sugar utilization pathways, whereas the remaining 125 global regulators control large and diverse sets of metabolic genes. The global LacI-TFs include the previously known regulators CcpA in Firmicutes, FruR in Enterobacteria, and PurR in Gammaproteobacteria, as well as the three novel regulators—GluR, GapR, and PckR—that are predicted to control the central carbohydrate metabolism in three lineages of Alphaproteobacteria. Phylogenetic analysis of regulators combined with the reconstructed regulons provides a model of evolutionary diversification of the LacI protein family. The obtained genomic collection of in silico reconstructed LacI-TF regulons in bacteria is available in the RegPrecise database (http://regprecise.lbl.gov). It provides a framework for future structural and functional classification of the LacI protein family and identification of molecular determinants of the DNA and ligand specificity. The inferred regulons can be also used for functional gene annotation and reconstruction of sugar catabolic networks in diverse bacterial lineages.
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Affiliation(s)
- Dmitry A Ravcheev
- Research Scientific Center for Bioinformatics, A.A. Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences Moscow, Russia
| | - Matvei S Khoroshkin
- Research Scientific Center for Bioinformatics, A.A. Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences Moscow, Russia
| | - Olga N Laikova
- Research Scientific Center for Bioinformatics, A.A. Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences Moscow, Russia
| | - Olga V Tsoy
- Research Scientific Center for Bioinformatics, A.A. Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences Moscow, Russia ; Faculty of Bioengineering and Bioinformatics, Moscow State University Moscow, Russia
| | - Natalia V Sernova
- Research Scientific Center for Bioinformatics, A.A. Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences Moscow, Russia
| | - Svetlana A Petrova
- Research Scientific Center for Bioinformatics, A.A. Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences Moscow, Russia ; Faculty of Bioengineering and Bioinformatics, Moscow State University Moscow, Russia
| | | | - Pavel S Novichkov
- Lawrence Berkeley National Laboratory, Genomics Division Berkeley, CA, USA
| | - Mikhail S Gelfand
- Research Scientific Center for Bioinformatics, A.A. Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences Moscow, Russia
| | - Dmitry A Rodionov
- Research Scientific Center for Bioinformatics, A.A. Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences Moscow, Russia ; Department of Bioinformatics, Sanford-Burnham Medical Research Institute La Jolla, CA, USA
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Novichkov PS, Kazakov AE, Ravcheev DA, Leyn SA, Kovaleva GY, Sutormin RA, Kazanov MD, Riehl W, Arkin AP, Dubchak I, Rodionov DA. RegPrecise 3.0--a resource for genome-scale exploration of transcriptional regulation in bacteria. BMC Genomics 2013; 14:745. [PMID: 24175918 PMCID: PMC3840689 DOI: 10.1186/1471-2164-14-745] [Citation(s) in RCA: 274] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2013] [Accepted: 10/28/2013] [Indexed: 11/27/2022] Open
Abstract
Background Genome-scale prediction of gene regulation and reconstruction of transcriptional regulatory networks in prokaryotes is one of the critical tasks of modern genomics. Bacteria from different taxonomic groups, whose lifestyles and natural environments are substantially different, possess highly diverged transcriptional regulatory networks. The comparative genomics approaches are useful for in silico reconstruction of bacterial regulons and networks operated by both transcription factors (TFs) and RNA regulatory elements (riboswitches). Description RegPrecise (http://regprecise.lbl.gov) is a web resource for collection, visualization and analysis of transcriptional regulons reconstructed by comparative genomics. We significantly expanded a reference collection of manually curated regulons we introduced earlier. RegPrecise 3.0 provides access to inferred regulatory interactions organized by phylogenetic, structural and functional properties. Taxonomy-specific collections include 781 TF regulogs inferred in more than 160 genomes representing 14 taxonomic groups of Bacteria. TF-specific collections include regulogs for a selected subset of 40 TFs reconstructed across more than 30 taxonomic lineages. Novel collections of regulons operated by RNA regulatory elements (riboswitches) include near 400 regulogs inferred in 24 bacterial lineages. RegPrecise 3.0 provides four classifications of the reference regulons implemented as controlled vocabularies: 55 TF protein families; 43 RNA motif families; ~150 biological processes or metabolic pathways; and ~200 effectors or environmental signals. Genome-wide visualization of regulatory networks and metabolic pathways covered by the reference regulons are available for all studied genomes. A separate section of RegPrecise 3.0 contains draft regulatory networks in 640 genomes obtained by an conservative propagation of the reference regulons to closely related genomes. Conclusions RegPrecise 3.0 gives access to the transcriptional regulons reconstructed in bacterial genomes. Analytical capabilities include exploration of: regulon content, structure and function; TF binding site motifs; conservation and variations in genome-wide regulatory networks across all taxonomic groups of Bacteria. RegPrecise 3.0 was selected as a core resource on transcriptional regulation of the Department of Energy Systems Biology Knowledgebase, an emerging software and data environment designed to enable researchers to collaboratively generate, test and share new hypotheses about gene and protein functions, perform large-scale analyses, and model interactions in microbes, plants, and their communities.
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Belousova EV, Chernousova EY, Dubinina GA, Tourova TP, Grabovich MY. Detection and analysis of sulfur metabolism genes in Sphaerotilus natans subsp. sulfidivorans representatives. Microbiology (Reading) 2013. [DOI: 10.1134/s0026261713050020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Comparative genomic and transcriptomic analyses reveal habitat differentiation and different transcriptional responses during pectin metabolism in Alishewanella species. Appl Environ Microbiol 2013; 79:6351-61. [PMID: 23934491 DOI: 10.1128/aem.02350-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Alishewanella species are expected to have high adaptability to diverse environments because they are isolated from different natural habitats. To investigate how the evolutionary history of Alishewanella species is reflected in their genomes, we performed comparative genomic and transcriptomic analyses of A. jeotgali, A. aestuarii, and A. agri, which were isolated from fermented seafood, tidal flat sediment, and soil, respectively. Genomic islands with variable GC contents indicated that invasion of prophage and transposition events occurred in A. jeotgali and A. agri but not in A. aestuarii. Habitat differentiation of A. agri from a marine environment to a terrestrial environment was proposed because the species-specific genes of A. agri were similar to those of soil bacteria, whereas those of A. jeotgali and A. aestuarii were more closely related to marine bacteria. Comparative transcriptomic analysis with pectin as a sole carbon source revealed different transcriptional responses in Alishewanella species, especially in oxidative stress-, methylglyoxal detoxification-, membrane maintenance-, and protease/chaperone activity-related genes. Transcriptomic and experimental data demonstrated that A. agri had a higher pectin degradation rate and more resistance to oxidative stress under pectin-amended conditions than the other 2 Alishewanella species. However, expression patterns of genes in the pectin metabolic pathway and of glyoxylate bypass genes were similar among all 3 Alishewanella species. Our comparative genomic and transcriptomic data revealed that Alishewanella species have evolved through horizontal gene transfer and habitat differentiation and that pectin degradation pathways in Alishewanella species are highly conserved, although stress responses of each Alishewanella species differed under pectin culture conditions.
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Cipriano MJ, Novichkov PN, Kazakov AE, Rodionov DA, Arkin AP, Gelfand MS, Dubchak I. RegTransBase--a database of regulatory sequences and interactions based on literature: a resource for investigating transcriptional regulation in prokaryotes. BMC Genomics 2013; 14:213. [PMID: 23547897 PMCID: PMC3639892 DOI: 10.1186/1471-2164-14-213] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 03/22/2013] [Indexed: 11/10/2022] Open
Abstract
Background Due to the constantly growing number of sequenced microbial genomes, comparative genomics has been playing a major role in the investigation of regulatory interactions in bacteria. Regulon inference mostly remains a field of semi-manual examination since absence of a knowledgebase and informatics platform for automated and systematic investigation restricts opportunities for computational prediction. Additionally, confirming computationally inferred regulons by experimental data is critically important. Description RegTransBase is an open-access platform with a user-friendly web interface publicly available at http://regtransbase.lbl.gov. It consists of two databases – a manually collected hierarchical regulatory interactions database based on more than 7000 scientific papers which can serve as a knowledgebase for verification of predictions, and a large set of curated by experts transcription factor binding sites used in regulon inference by a variety of tools. RegTransBase captures the knowledge from published scientific literature using controlled vocabularies and contains various types of experimental data, such as: the activation or repression of transcription by an identified direct regulator; determination of the transcriptional regulatory function of a protein (or RNA) directly binding to DNA or RNA; mapping of binding sites for a regulatory protein; characterization of regulatory mutations. Analysis of the data collected from literature resulted in the creation of Putative Regulons from Experimental Data that are also available in RegTransBase. Conclusions RegTransBase is a powerful user-friendly platform for the investigation of regulation in prokaryotes. It uses a collection of validated regulatory sequences that can be easily extracted and used to infer regulatory interactions by comparative genomics techniques thus assisting researchers in the interpretation of transcriptional regulation data.
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Affiliation(s)
- Michael J Cipriano
- Department of Microbiology, University of California Davis, Davis, CA 95616, USA
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Faria JP, Overbeek R, Xia F, Rocha M, Rocha I, Henry CS. Genome-scale bacterial transcriptional regulatory networks: reconstruction and integrated analysis with metabolic models. Brief Bioinform 2013; 15:592-611. [DOI: 10.1093/bib/bbs071] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Tsoy OV, Pyatnitskiy MA, Kazanov MD, Gelfand MS. Evolution of transcriptional regulation in closely related bacteria. BMC Evol Biol 2012; 12:200. [PMID: 23039862 PMCID: PMC3735044 DOI: 10.1186/1471-2148-12-200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 09/26/2012] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND The exponential growth of the number of fully sequenced genomes at varying taxonomic closeness allows one to characterize transcriptional regulation using comparative-genomics analysis instead of time-consuming experimental methods. A transcriptional regulatory unit consists of a transcription factor, its binding site and a regulated gene. These units constitute a graph which contains so-called "network motifs", subgraphs of a given structure. Here we consider genomes of closely related Enterobacteriales and estimate the fraction of conserved network motifs and sites as well as positions under selection in various types of non-coding regions. RESULTS Using a newly developed technique, we found that the highest fraction of positions under selection, approximately 50%, was observed in synvergon spacers (between consecutive genes from the same strand), followed by ~45% in divergon spacers (common 5'-regions), and ~10% in convergon spacers (common 3'-regions). The fraction of selected positions in functional regions was higher, 60% in transcription factor-binding sites and ~45% in terminators and promoters. Small, but significant differences were observed between Escherichia coli and Salmonella enterica. This fraction is similar to the one observed in eukaryotes.The conservation of binding sites demonstrated some differences between types of regulatory units. In E. coli, strains the interactions of the type "local transcriptional factor gene" turned out to be more conserved in feed-forward loops (FFLs) compared to non-motif interactions. The coherent FFLs tend to be less conserved than the incoherent FFLs. A natural explanation is that the former imply functional redundancy. CONCLUSIONS A naïve hypothesis that FFL would be highly conserved turned out to be not entirely true: its conservation depends on its status in the transcriptional network and also from its usage. The fraction of positions under selection in intergenic regions of bacterial genomes is roughly similar to that of eukaryotes. Known regulatory sites explain 20±5% of selected positions.
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Affiliation(s)
- Olga V Tsoy
- Institute for Information Transmission Problems, RAS, Bolshoi Karetny per. 19, Moscow 127994, Russia
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Reddy VS, Shlykov MA, Castillo R, Sun EI, Saier MH. The major facilitator superfamily (MFS) revisited. FEBS J 2012; 279:2022-35. [PMID: 22458847 DOI: 10.1111/j.1742-4658.2012.08588.x] [Citation(s) in RCA: 337] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The major facilitator superfamily (MFS) is the largest known superfamily of secondary carriers found in the biosphere. It is ubiquitously distributed throughout virtually all currently recognized organismal phyla. This superfamily currently (2012) consists of 74 families, each of which is usually concerned with the transport of a certain type of substrate. Many of these families, defined phylogenetically, do not include even a single member that is functionally characterized. In this article, we probe the evolutionary origins of these transporters, providing evidence that they arose from a single 2-transmembrane segment (TMS) hairpin structure that triplicated to give a 6-TMS unit that duplicated to a 12-TMS protein, the most frequent topological type of these permeases. We globally examine MFS protein topologies, focusing on exceptional proteins that deviate from the norm. Nine distantly related families appear to have members with 14 TMSs in which the extra two are usually centrally localized between the two 6-TMS repeat units. They probably have arisen by intragenic duplication of an adjacent hairpin. This alternative topology probably arose multiple times during MFS evolution. Convincing evidence for MFS permeases with fewer than 12 TMSs was not forthcoming, leading to the suggestion that all 12 TMSs are required for optimal function. Some homologs appear to have 13, 14, 15 or 16 TMSs, and the probable locations of the extra TMSs were identified. A few MFS permeases are fused to other functional domains or are fully duplicated to give 24-TMS proteins with dual functions. Finally, the MFS families with no known function were subjected to genomic context analyses leading to functional predictions.
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Affiliation(s)
- Vamsee S Reddy
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA, USA
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