Identification of genes unique to Mo-independent nitrogenase systems in diverse diazotrophs

1999 ◽  
Vol 45 (4) ◽  
pp. 312-317 ◽  
Author(s):  
Telisa M Loveless ◽  
Paul E Bishop

A number of nitrogen-fixing bacteria were screened using PCR for genes (vnfG and anfG) unique to the V-containing nitrogenase (vnf) and the Fe-only nitrogenase (anf) systems. Products with sequences similar to that of vnfG were obtained from Azotobacter paspali and Azotobacter salinestris genomic DNAs, and products with sequences similar to that of anfG were obtained from Azomonas macrocytogenes, Rhodospirillum rubrum, and Azotobacter paspali DNAs. Phylogenetic analysis of the deduced amino acid sequences of anfG and vnfG genes shows that each gene product forms a distinct cluster. Furthermore, amplification of an internal 839-bp region in anfD and vnfD yielded a product similar to anfD from Heliobacterium gestii and a product similar to vnfD from Azotobacter paspali and Azotobacter salinestris. Phylogenetic analysis of NifD, VnfD, and AnfD amino acid sequences indicates that AnfD and VnfD sequences are more closely related to each other than either is to NifD. The results of this study suggest that Azotobacter salinestris possesses the potential to express the vanadium (V)-containing nitrogenase (nitrogenase 2) and that R. rubrum, Azomonas macrocytogenes, and H. gestii possess the potential to express the Fe-only nitrogenase (nitrogenase 3). Like Azotobacter vinelandii, Azotobacter paspali appears to have the potential to express both the V-containing nitrogenase and the Fe-only nitrogenase.Key words: Mo-independent nitrogenase systems, diverse diazotrophs, vnfG, anfG.

1986 ◽  
Vol 239 (1) ◽  
pp. 69-75 ◽  
Author(s):  
J Deistung ◽  
R N F Thorneley

Flavodoxin in the hydroquinone state acts as an electron donor to nitrogenase in several nitrogen-fixing organisms. The mid-point potentials for the oxidized-semiquinone and semiquinone-hydroquinone couples of flavodoxins isolated from facultative anaerobe Klebsiella pneumoniae (nifF-gene product, KpFld) and the obligate aerobe Azotobacter chroococcum (AcFld) were determined as a function of pH. The mid-point potentials of the semiquinone-hydroquinone couples of KpFld and AcFld are essentially independent of pH over the range pH 7-9, being -422 mV and -522 mV (normal hydrogen electrode) at pH 7.5 respectively. The mid-point potentials of the quinone-semiquinone couples at pH 7.5 are -200 mV (KpFld) and -133 mV (AcFld) with delta Em/pH of -65 +/- 4 mV (KpFld) and -55 +/- 2 mV (AcFld) over the range pH 7.0-9.5. This indicates that reduction of the quinone is coupled to protonation to yield a neutral semiquinone. The significance of these values with respect to electron transport to nitrogenase is discussed. The amino acid compositions, the N- and C-terminal amino acid sequences and the u.v.-visible spectra of KpFld and AcFld were determined and are compared with published data for flavodoxins isolated from Azotobacter vinelandii.


2018 ◽  
Vol 44 (1) ◽  
pp. 20
Author(s):  
Eloiza Teles Caldart ◽  
Helena Mata ◽  
Cláudio Wageck Canal ◽  
Ana Paula Ravazzolo

Background: Phylogenetic analyses are an essential part in the exploratory assessment of nucleic acid and amino acid sequences. Particularly in virology, they are able to delineate the evolution and epidemiology of disease etiologic agents and/or the evolutionary path of their hosts. The objective of this review is to help researchers who want to use phylogenetic analyses as a tool in virology and molecular epidemiology studies, presenting the most commonly used methodologies, describing the importance of the different techniques, their peculiar vocabulary and some examples of their use in virology.Review: This article starts presenting basic concepts of molecular epidemiology and molecular evolution, emphasizing their relevance in the context of viral infectious diseases. It presents a session on the vocabulary relevant to the subject, bringing readers to a minimum level of knowledge needed throughout this literature review. Within its main subject, the text explains what a molecular phylogenetic analysis is, starting from a multiple alignment of nucleotide or amino acid sequences. The different software used to perform multiple alignments may apply different algorithms. To build a phylogeny based on amino acid or nucleotide sequences it is necessary to produce a data matrix based on a model for nucleotide or amino acid replacement, also called evolutionary model. There are a number of evolutionary models available, varying in complexity according to the number of parameters (transition, transversion, GC content, nucleotide position in the codon, among others). Some papers presented herein provide techniques that can be used to choose evolutionary models. After the model is chosen, the next step is to opt for a phylogenetic reconstruction method that best fits the available data and the selected model. Here we present the most common reconstruction methods currently used, describing their principles, advantages and disadvantages. Distance methods, for example, are simpler and faster, however, they do not provide reliable estimations when the sequences are highly divergent. The accuracy of the analysis with probabilistic models (neighbour joining, maximum likelihood and bayesian inference) strongly depends on the adherence of the actual data to the chosen development model. Finally, we also explore topology confidence tests, especially the most used one, the bootstrap. To assist the reader, this review presents figures to explain specific situations discussed in the text and numerous examples of previously published scientific articles in virology that demonstrate the importance of the techniques discussed herein, as well as their judicious use.Conclusion: The DNA sequence is not only a record of phylogeny and divergence times, but also keeps signs of how the evolutionary process has shaped its history and also the elapsed time in the evolutionary process of the population. Analyses of genomic sequences by molecular phylogeny have demonstrated a broad spectrum of applications. It is important to note that for the different available data and different purposes of phylogenies, reconstruction methods and evolutionary models should be wisely chosen. This review provides theoretical basis for the choice of evolutionary models and phylogenetic reconstruction methods best suited to each situation. In addition, it presents examples of diverse applications of molecular phylogeny in virology.


2012 ◽  
Vol 17 (4) ◽  
pp. 4-8
Author(s):  
A. S Klimentov ◽  
A. P Gmyl ◽  
A. M Butenko ◽  
L. V Gmyl ◽  
O. V Isaeva ◽  
...  

The nucleotide sequence of M= (1398 nucleotides and L= (6186 nucleotides) segments of the genome of Bhanja virus and L-segment (1297 nucleotides) of Kismayo virus has been partially determined. Phylogenetic analysis of deduced amino acid sequences showed that these viruses are novel members of the Flebovirus (Phlebovirus) genus in the family Bunyaviridae


Author(s):  
Sona. S Dev ◽  
P. Poornima ◽  
Akhil Venu

Eggplantor brinjal (Solanum melongena L.), is highly susceptible to various soil-borne diseases. The extensive use of chemical fungicides to combat these diseases can be minimized by identification of resistance gene analogs (RGAs) in wild species of cultivated plants.In the present study, degenerate PCR primers for the conserved regions ofnucleotide binding site-leucine rich repeat (NBS-LRR) were used to amplify RGAs from wild relatives of eggplant (Black nightshade (Solanum nigrum), Indian nightshade (Solanumviolaceum)and Solanu mincanum) which showed resistance to the bacterial wilt pathogen, Ralstonia solanacearumin the preliminary investigation. The amino acid sequence of the amplicons when compared to each other and to the amino acid sequences of known RGAs deposited in Gen Bank revealed significant sequence similarity. The phylogenetic analysis indicated that they belonged to the toll interleukin-1 receptors (TIR)-NBS-LRR type R-genes. Multiple sequence alignment with other known R genes showed significant homology with P-loop, Kinase 2 and GLPL domains of NBS-LRR class genes. There has been no report on R genes from these wild eggplants and hence the diversity analysis of these novel RGAs can lead to the identification of other novel R genes within the germplasm of different brinjal plants as well as other species of Solanum.


2006 ◽  
Vol 138 (2) ◽  
pp. 138-146 ◽  
Author(s):  
O. Mittapalli ◽  
R.H. Shukle ◽  
I.L. Wise

AbstractMariner-like element sequences were recovered from the genome of the orange wheat midge, Sitodiplosis mosellana (Géhin), with degenerate PCR primers designed to conserved regions of mariner transposases. The deduced amino acid sequences of the mariner-like transposases from S. mosellana showed 67% to 78% identity with the peptide sequences of other mariner transposases. A phylogenetic analysis revealed that the mariner-like elements from S. mosellana grouped in the mauritiana subfamily of mariner transposons. Results from Southern blot analysis suggest mariner-like elements are at a moderate copy number in the genome of S. mosellana.


1990 ◽  
Vol 171 (4) ◽  
pp. 1375-1380 ◽  
Author(s):  
S Vijayasaradhi ◽  
B Bouchard ◽  
A N Houghton

The gp75 antigen is an abundant intracellular glycoprotein expressed in melanosomes of human pigmented melanocytes and melanomas. IgG antibodies in sera of a patient with metastatic melanoma have been shown to immunoprecipitate gp75, suggesting that immunological tolerance against gp75 can be broken. The mouse mAb TA99, which specifically recognizes gp75, was used to isolate and purify the antigen. Amino acid sequences of three internal peptides were determined from the purified gp75 polypeptide. cDNA clones were isolated by screening with oligonucleotides based on these peptide sequences. The gp75 peptides and cDNA had approximately 90% identity with, respectively, the derived amino acid and nucleotide sequences of a mouse gene that maps to the b (brown) locus. The brown locus determines coat color in the mouse, suggesting that gp75 regulates or influences the type of melanin synthesized.


2000 ◽  
Vol 46 (4) ◽  
pp. 325-332 ◽  
Author(s):  
Sanae Kato ◽  
Isao Yumoto

To examine the distribution of the Na+-translocating NADH-quinone reductase (Na+-NQR) among marine bacteria, we developed a simple screening method for the detection of this enzyme. By reference to the homologous sequences of the Na+-NQR operons from Vibrio alginolyticus and Haemophilus influenzae, a pair of primers was designed for amplification of a part of the sixth ORF (nqr6) of the Na+-NQR operon. When PCR was performed using genomic DNA from 13 marine bacteria, a 0.9-kbp fragment corresponding to nqr6 was amplified in 10 strains. Although there were three PCR-negative strains phylogenetically, based on the sequence of the 16S rRNA, these were placed far from the PCR-positive strains. No product was observed in the case of nonmarine bacteria. The nucleotide and predicted amino acid sequences of nqr6 were highly conserved among the PCR-positive marine bacteria. A phylogenetic analysis of marine bacteria, based on nqr6 sequencing, was performed.Key words: Na+-translocating, NADH-quinone reductase, marine bacteria, PCR.


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