scholarly journals The Evolution of Molybdenum Dependent Nitrogenase in Cyanobacteria

Biology ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 329
Author(s):  
Tomoaki Watanabe ◽  
Tokumasa Horiike

Nitrogen fixation plays a crucial role in the nitrogen cycle by helping to convert nitrogen into a form usable by other organisms. Bacteria capable of fixing nitrogen are found in six phyla including Cyanobacteria. Molybdenum dependent nitrogenase (nif) genes are thought to share a single origin as they have homologs in various phyla. However, diazotrophic bacteria have a mosaic distribution within the cyanobacterial lineage. Therefore, the aim of this study was to determine the cause of this mosaic distribution. We identified nif gene operon structures in the genomes of 85 of the 179 cyanobacterial strains for which whole genome sequences were available. Four nif operons were conserved in each diazotroph Cyanobacterium, although there were some gene translocations and insertions. Phylogenetic inference of these genes did not reveal horizontal gene transfer from outside the phylum Cyanobacteria. These results support the hypothesis that the mosaic distribution of diazotrophic bacteria in the cyanobacterial lineage is the result of the independent loss of nif genes inherited from common cyanobacterial ancestors in each lineage.

2010 ◽  
Vol 18 (02) ◽  
pp. 261-275 ◽  
Author(s):  
MICHAEL SYVANEN ◽  
JONATHAN DUCORE

The availability of whole genome sequences from multiple metazoan phyla is making it possible to determine their phylogeny. We have found that a sea urchin and human define a clade that excludes a tunicate, contradicting both classical and recent molecular studies that place the tunicate and vertebrate in the Chordate phylum. Intriguingly, by means of a novel four taxa analysis, we have partitioned the 2000 proteins responsible for this assignment into two groups. One group, containing about 40% of the proteins, supports the classical assemblage of the tunicate with vertebrates, while the remaining group places the tunicate outside of the chordate assemblage. The existence of these two phylogenetic groups is robustly maintained in five, six and nine taxa analyses. These results suggest that major horizontal gene transfer events occurred during the emergence of one of the metazoan phyla. The simplest explanation is that the modern tunicate (as represented by Ciona intestinalis) began as a hybrid between a primitive vertebrate and some other organism, perhaps from an extinct and unidentified protostome phylum, at a time close to but after the diversification of the chordates and echinoderms and before the lineages leading to Drosophila melanogaster and Caenorhabditis elegans diverged.


2020 ◽  
Vol 12 (11) ◽  
pp. 2002-2014
Author(s):  
Ling-Ling Yang ◽  
Zhao Jiang ◽  
Yan Li ◽  
En-Tao Wang ◽  
Xiao-Yang Zhi

Abstract Rhizobia are soil bacteria capable of forming symbiotic nitrogen-fixing nodules associated with leguminous plants. In fast-growing legume-nodulating rhizobia, such as the species in the family Rhizobiaceae, the symbiotic plasmid is the main genetic basis for nitrogen-fixing symbiosis, and is susceptible to horizontal gene transfer. To further understand the symbioses evolution in Rhizobiaceae, we analyzed the pan-genome of this family based on 92 genomes of type/reference strains and reconstructed its phylogeny using a phylogenomics approach. Intriguingly, although the genetic expansion that occurred in chromosomal regions was the main reason for the high proportion of low-frequency flexible gene families in the pan-genome, gene gain events associated with accessory plasmids introduced more genes into the genomes of nitrogen-fixing species. For symbiotic plasmids, although horizontal gene transfer frequently occurred, transfer may be impeded by, such as, the host’s physical isolation and soil conditions, even among phylogenetically close species. During coevolution with leguminous hosts, the plasmid system, including accessory and symbiotic plasmids, may have evolved over a time span, and provided rhizobial species with the ability to adapt to various environmental conditions and helped them achieve nitrogen fixation. These findings provide new insights into the phylogeny of Rhizobiaceae and advance our understanding of the evolution of symbiotic nitrogen fixation.


2009 ◽  
Vol 364 (1527) ◽  
pp. 2275-2289 ◽  
Author(s):  
Anders Norman ◽  
Lars H. Hansen ◽  
Søren J. Sørensen

Comparative whole-genome analyses have demonstrated that horizontal gene transfer (HGT) provides a significant contribution to prokaryotic genome innovation. The evolution of specific prokaryotes is therefore tightly linked to the environment in which they live and the communal pool of genes available within that environment. Here we use the term supergenome to describe the set of all genes that a prokaryotic ‘individual’ can draw on within a particular environmental setting. Conjugative plasmids can be considered particularly successful entities within the communal pool, which have enabled HGT over large taxonomic distances. These plasmids are collections of discrete regions of genes that function as ‘backbone modules’ to undertake different aspects of overall plasmid maintenance and propagation. Conjugative plasmids often carry suites of ‘accessory elements’ that contribute adaptive traits to the hosts and, potentially, other resident prokaryotes within specific environmental niches. Insight into the evolution of plasmid modules therefore contributes to our knowledge of gene dissemination and evolution within prokaryotic communities. This communal pool provides the prokaryotes with an important mechanistic framework for obtaining adaptability and functional diversity that alleviates the need for large genomes of specialized ‘private genes’.


2018 ◽  
Vol 62 (9) ◽  
Author(s):  
Eva Hong ◽  
Ala-Eddine Deghmane ◽  
Muhamed-Kheir Taha

ABSTRACT We report the detection in France of a beta-lactamase-producing invasive meningococcal isolate. Whole-genome sequencing of the isolate revealed a ROB-1-type beta-lactamase gene that is frequently encountered in Haemophilus influenzae, suggesting horizontal transfer between isolates of these bacterial species. Beta-lactamases are exceptional in meningococci, with no reports for more than 2 decades. This report is worrying, as the expansion of such isolates may jeopardize the effective treatment against invasive meningococcal disease.


2019 ◽  
Vol 14 (14) ◽  
pp. 1191-1197 ◽  
Author(s):  
Thijs Bosch ◽  
Rogier Schade ◽  
Fabian Landman ◽  
Leo Schouls ◽  
Karin van Dijk

Aim: To show that a strain of Aeromonas hydrophila became resistant to carbapenems by interspecies transfer of a plasmid using long-read sequencing. Material & methods: Whole genome sequencing of the four isolates was done using Illumina Hiseq, while the plasmid was reconstructed using the MinION sequencer. The resistome was identified with ResFinder. Results: Whole genome sequencing and long-read sequencing showed that all isolates carried a blaVIM-1 gene located on a 165 kb incA/C plasmid. ResFinder confirmed that the resistome of the plasmid, comprising 13 resistance genes, was identical within all isolates. Discussion: Long-read sequencing using the MinION successfully reconstructed a plasmid that was identical in all isolates, providing evidence for horizontal gene transfer of this blaVIM-1 gene carrying plasmid within the patient.


2010 ◽  
Vol 55 (2) ◽  
pp. 623-630 ◽  
Author(s):  
Hidemasa Izumiya ◽  
Tsuyoshi Sekizuka ◽  
Hideo Nakaya ◽  
Masumi Taguchi ◽  
Akio Oguchi ◽  
...  

ABSTRACTSalmonella entericaserovar Typhimurium is frequently associated with life-threatening systemic infections, and the recent global emergence of multidrug resistance inS. entericaisolates from agricultural and clinical settings has raised concerns. In this study, we determined the whole-genome sequence of fluoroquinolone-resistantS. entericaserovar Typhimurium T000240 strain (DT12) isolated from human gastroenteritis in 2000. Comparative genome analysis revealed that T000240 displays high sequence similarity to strain LT2, which was originally isolated in 1940, indicating that progeny of LT2 might be reemerging. T000240 possesses a unique 82-kb genomic island, designated as GI-DT12, which is composed of multidrug resistance determinants, including a Tn2670-like composite transposon (class 1 integron [intI1,blaoxa-30,aadA1,qacEΔ1, andsul1], mercury resistance proteins, and chloramphenicol acetyltransferase), a Tn10-like tetracycline resistance protein (tetA), the aerobactin iron-acquisition siderophore system (lutAandlucABC), and an iron transporter (sitABCD). Since GI-DT12 is flanked by IS1derivatives, IS1-mediated recombination likely played a role in the acquisition of this genomic island through horizontal gene transfer. The aminoglycoside-(3)-N-acetyltransferase (aac(3)) gene and a class 1 integron harboring thedfrA1gene cassette responsible for gentamicin and trimethoprim resistance, respectively, were identified on plasmid pSTMDT12_L and appeared to have been acquired through homologous recombination with IS26. This study represents the first characterization of the unique genomic island GI-DT12 that appears to be associated with possible IS1-mediated recombination inS. entericaserovar Typhimurium. It is expected that future whole-genome studies will aid in the characterization of the horizontal gene transfer events for the emergingS. entericaserovar Typhimurium strains.


2019 ◽  
Author(s):  
Başak Öztürk ◽  
Johannes Werner ◽  
Jan P. Meier-Kolthoff ◽  
Boyke Bunk ◽  
Cathrin Spröer ◽  
...  

AbstractBiodegradation of the phenylurea herbicide linuron appears a specialization within a specific clade of the Variovorax genus. The linuron catabolic ability is likely acquired by horizontal gene transfer but the mechanisms involved are not known. The full genome sequences of six linuron degrading Variovorax strains isolated from geographically distant locations were analyzed to acquire insight in the mechanisms of genetic adaptation towards linuron metabolism in Variovorax. Whole genome sequence analysis confirmed the phylogenetic position of the linuron degraders in a separate clade within Variovorax and indicated their unlikely origin from a common ancestral linuron degrader. The linuron degraders differentiated from non-degraders by the presence of multiple plasmids of 20 to 839 kb, including plasmids of unknown plasmid groups. The linuron catabolic gene clusters showed (i) high conservation and synteny and (ii) strain-dependent distribution among the different plasmids. All were bordered by IS1071 elements forming composite transposon structures appointing IS1071 as key for catabolic gene recruitment. Most of the strain carried at least one broad host range plasmid that might have been a second instrument for catabolic gene acquisition. We conclude that clade 1Variovorax strains, despite their different geographical origin, made use of a limited genetic repertoire to acquire linuron biodegradation.ImportanceThe genus Variovorax and especially a clade of strains that phylogenetically separates from the majority of Variovorax species, appears to be a specialist in the biodegradation of the phenyl urea herbicide linuron. Horizontal gene transfer (HGT) likely played an essential role in the genetic adaptation of those strain to acquire the linuron catabolic genotype. However, we do not know the genetic repertoire involved in this adaptation both regarding catabolic gene functions as well as gene functions that promote HGT neither do we know how this varies between the different strains. These questions are addressed in this paper by analyzing the full genome sequences of six linuron degrading Variovorax strains. This knowledge is important for understanding the mechanisms that steer world-wide genetic adaptation in a particular species and this for a particular phenotypic trait as linuron biodegradation.


2021 ◽  
Vol 12 ◽  
Author(s):  
Abdullah Ibn Mafiz ◽  
Yingshu He ◽  
Wei Zhang ◽  
Yifan Zhang

Fifteen soil and 45 vegetable samples from Detroit community gardens were analyzed for potential antimicrobial resistance contamination. Soil bacteria were isolated and tested by antimicrobial susceptibility profiling, horizontal gene transfer, and whole-genome sequencing. High-throughput 16S rRNA sequencing analysis was conducted on collected soil samples to determine the total bacterial composition. Of 226 bacterial isolates recovered, 54 were from soil and 172 from vegetables. A high minimal inhibitory concentration (MIC) was defined as the MIC greater than or equal to the resistance breakpoint of Escherichia coli for Gram-negative bacteria or Staphylococcus aureus for Gram-positive bacteria. The high MIC was observed in 63.4 and 69.8% of Gram-negative isolates from soil and vegetables, respectively, against amoxicillin/clavulanic acid, as well as 97.5 and 82.7% against ampicillin, 97.6 and 90.7% against ceftriaxone, 85.4 and 81.3% against cefoxitin, 65.8 and 70.5% against chloramphenicol, and 80.5 and 59.7% against ciprofloxacin. All Gram-positive bacteria showed a high MIC to gentamicin, kanamycin, and penicillin. Forty of 57 isolates carrying tetM (70.2%) successfully transferred tetracycline resistance to a susceptible recipient via conjugation. Whole-genome sequencing analysis identified a wide array of antimicrobial resistance genes (ARGs), including those encoding AdeIJK, Mex, and SmeDEF efflux pumps, suggesting a high potential of the isolates to become antimicrobial resistant, despite some inconsistency between the gene profile and the resistance phenotype. In conclusion, soil bacteria in urban community gardens can serve as a reservoir of antimicrobial resistance with the potential to transfer to clinically important pathogens, resulting in food safety and public health concerns.


2021 ◽  
Vol 12 ◽  
Author(s):  
Vanina Guernier-Cambert ◽  
Julian Trachsel ◽  
Joel Maki ◽  
Jing Qi ◽  
Matthew J. Sylte ◽  
...  

Antibiotic-resistant Campylobacter constitutes a serious threat to public health. The clonal expansion of resistant strains and/or the horizontal spread of resistance genes to other strains and species can hinder the clinical effectiveness of antibiotics to treat severe campylobacteriosis. Still, gaps exist in our understanding of the risks of acquisition and spread of antibiotic resistance in Campylobacter. While the in vitro transfer of antimicrobial resistance genes between Campylobacter species via natural transformation has been extensively demonstrated, experimental studies have favored the use of naked DNA to obtain transformants. In this study, we used experimental designs closer to real-world conditions to evaluate the possible transfer of antimicrobial resistance genes between Campylobacter strains of the same or different species (Campylobacter coli or Campylobacter jejuni) and originating from different animal hosts (swine or turkeys). This was evaluated in vitro through co-culture experiments and in vivo with dual-strain inoculation of turkeys, followed by whole genome sequencing of parental and newly emerged strains. In vitro, we observed four independent horizontal gene transfer events leading to the acquisition of resistance to beta-lactams (blaOXA), aminoglycosides [aph(2′′)-If and rpsL] and tetracycline [tet(O)]. Observed events involved the displacement of resistance-associated genes by a mutated version, or the acquisition of genomic islands harboring a resistance determinant by homologous recombination; we did not detect the transfer of resistance-carrying plasmids even though they were present in some strains. In vivo, we recovered a newly emerged strain with dual-resistance pattern and identified the replacement of an existing non-functional tet(O) by a functional tet(O) in the recipient strain. Whole genome comparisons allowed characterization of the events involved in the horizontal spread of resistance genes between Campylobacter following in vitro co-culture and in vivo dual inoculation. Our study also highlights the potential for antimicrobial resistance transfer across Campylobacter species originating from turkeys and swine, which may have implications for farms hosting both species in close proximity.


2019 ◽  
Author(s):  
Walter J. Lapadula ◽  
María L. Mascotti ◽  
Maximiliano Juri Ayub

ABSTRACTRibosome inactivating proteins (RIPs) are RNA N-glycosidases that depurinate a specific adenine residue in the conserved sarcin/ricin loop of 28S rRNA. These enzymes are widely distributed among plants and bacteria. Recently, we have described RIP genes in mosquitoes belonging to the Culicinae subfamily (Aedini and Culicini tribes). We have also shown that these genes are derived from a single event of horizontal gene transfer (HGT) from a prokaryotic donor. In the present work, we show the existence of two RIP encoding genes in the genome of the whitefly Bemisia tabaci (a hemiptera species belonging to the Aleyrodidae family, distantly related to mosquitoes). Contamination artifacts were ruled out analyzing three independent Bemisia tabaci genome databases. In contrast to mosquitoes RIPs, the whitefly genes harbor introns and, according to transcriptomic evidence, are transcribed and spliced. Interestingly, phylogenetic inference combined with taxonomic distribution strongly supports that whitefly RIP genes are derived from an independent HGT event from a plant source. Our results suggest that RIP genes fill a functional niche in insects.


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