scholarly journals Identification of Campylobacter jejuni ATCC 43431-Specific Genes by Whole Microbial Genome Comparisons

2004 ◽  
Vol 186 (14) ◽  
pp. 4781-4795 ◽  
Author(s):  
Frédéric Poly ◽  
Deborah Threadgill ◽  
Alain Stintzi

ABSTRACT This study describes a novel approach to identify unique genomic DNA sequences from the unsequenced strain C. jejuni ATCC 43431 by comparison with the sequenced strain C. jejuni NCTC 11168. A shotgun DNA microarray was constructed by arraying 9,600 individual DNA fragments from a C. jejuni ATCC 43431 genomic library onto a glass slide. DNA fragments unique to C. jejuni ATCC 43431 were identified by competitive hybridization to the array with genomic DNA of C. jejuni NCTC 11168. The plasmids containing unique DNA fragments were sequenced, allowing the identification of up to 130 complete and incomplete genes. Potential biological roles were assigned to 66% of the unique open reading frames. The mean G+C content of these unique genes (26%) differs significantly from the G+C content of the entire C. jejuni genome (30.6%). This suggests that they may have been acquired through horizontal gene transfer from an organism with a G+C content lower than that of C. jejuni. Because the two C. jejuni strains differ by Penner serotype, a large proportion of the unique ATCC 43431 genes encode proteins involved in lipooligosaccharide and capsular biosynthesis, as expected. Several unique open reading frames encode enzymes which may contribute to genetic variability, i.e., restriction-modification systems and integrases. Interestingly, many of the unique C. jejuni ATCC 43431 genes show identity with a possible pathogenicity island from Helicobacter hepaticus and components of a potential type IV secretion system. In conclusion, this study provides a valuable resource to further investigate Campylobacter diversity and pathogenesis.

2013 ◽  
Vol 26 (5) ◽  
pp. 554-565 ◽  
Author(s):  
Claudia E. Calderón ◽  
Alejandro Pérez-García ◽  
Antonio de Vicente ◽  
Francisco M. Cazorla

To determine the genetic basis by which 2-hexyl, 5-propyl resorcinol (HPR) is produced by the biocontrol rhizobacterium Pseudomonas chlororaphis (formerly known as P. fluorescens) PCL1606, the presence and role of dar genes were investigated. To accomplish this aim, the pCGNOV-1 plasmid was isolated from a PCL1606 genomic library and was shown to hybridize to various dar probes by Southern blot. An analysis of the pCGNOV-1 genomic DNA revealed the presence of five open reading frames that were homologous to dar genes and had an organization that resembled the arrangement of previously described P. chlororaphis strains. Phylogenetic studies resulted in the clustering of PCL1606 with the P. chlororaphis subgroup, which supported the renaming of this strain from P. fluorescens to P. chlororaphis PCL1606. The construction of insertional mutants for each homologous dar gene in P. chlororaphis PCL1606 along with their corresponding complemented derivative strains restored HPR production and confirmed the key role of the dar A and darB genes in HPR production and in the antagonistic phenotype. Finally, biocontrol assays were performed on avocado–Rosellinia and tomato–Fusarium test systems using the HPR-defective and -complemented derivative strains generated here and demonstrated the crucial role of the biosynthetic dar genes in the biocontrol phenotype of P. chlororaphis PCL1606. This biocontrol phenotype is dependent on the dar genes via their production of the HPR antibiotic. Some of the dar genes not directly involved in the biosynthesis of HPR, such as darS or darR, might contribute to regulatory features of HPR production.


Genome ◽  
2001 ◽  
Vol 44 (4) ◽  
pp. 716-728 ◽  
Author(s):  
Pavel Neumann ◽  
Marcela Nouzová ◽  
Jirí Macas

A set of pea DNA sequences representing the most abundant genomic repeats was obtained by combining several approaches. Dispersed repeats were isolated by screening a short-insert genomic library using genomic DNA as a probe. Thirty-two clones ranging from 149 to 2961 bp in size and from 1000 to 39 000/1C in their copy number were sequenced and further characterized. Fourteen clones were identified as retrotransposon-like sequences, based on their homologies to known elements. Fluorescence in situ hybridization using clones of reverse transcriptase and integrase coding sequences as probes revealed that corresponding retroelements were scattered along all pea chromosomes. Two novel families of tandem repeats, named PisTR-A and PisTR-B, were isolated by screening a genomic DNA library with Cot-1 DNA and by employing genomic self-priming PCR, respectively. PisTR-A repeats are 211–212 bp long, their abundance is 2 × 104 copies/1C, and they are partially clustered in a secondary constriction of one chromosome pair with the rest of their copies dispersed on all chromosomes. PisTR-B sequences are of similar abundance (104 copies/1C) but differ from the "A" family in their monomer length (50 bp), high A/T content, and chromosomal localization in a limited number of discrete bands. These bands are located mainly in (sub)telomeric and pericentromeric regions, and their patterns, together with chromosome morphology, allow discrimination of all chromosome types within the pea karyotype. Whereas both tandem repeat families are mostly specific to the genus Pisum, many of the dispersed repeats were detected in other legume species, mainly those in the genus Vicia.Key words: repetitive DNA, plant genome, retroelements, satellite DNA, Pisum sativum.


1984 ◽  
Vol 4 (11) ◽  
pp. 2498-2508
Author(s):  
K S Chang ◽  
W E Zimmer ◽  
D J Bergsma ◽  
J B Dodgson ◽  
R J Schwartz

Genes representing six different actin isoforms were isolated from a chicken genomic library. Cloned actin cDNAs as well as tissue-specific mRNAs enriched in different actin species were used as hybridization probes to group individual actin genomic clones by their relative thermal stability. Restriction maps showed that these actin genes were derived from separate and nonoverlapping regions of genomic DNA. Of the six isolated genes, five included sequences from both the 5' and 3' ends of the actin-coding area. Amino acid sequence analysis from both the NH2- and COOH-terminal regions provided for the unequivocal identification of these genes. The striated isoforms were represented by the isolated alpha-skeletal, alpha-cardiac, and alpha-smooth muscle actin genes. The nonmuscle isoforms included the beta-cytoplasmic actin gene and an actin gene fragment which lacked the 5' coding and flanking sequence; presumably, this region of DNA was removed from this gene during construction of the genomic library. Unexpectedly, a third nonmuscle chicken actin gene was found which resembled the amphibian type 5 actin isoform (J. Vandekerckhove, W. W. Franke, and K. Weber, J. Mol. Biol., 152:413-426). This nonmuscle actin type has not been previously detected in warm-blooded vertebrates. We showed that interspersed, repeated DNA sequences closely flanked the alpha-skeletal, alpha-cardiac, beta-, and type 5-like actin genes. The repeated DNA sequences which surround the alpha-skeletal actin-coding regions were not related to repetitious DNA located on the other actin genes. Analysis of genomic DNA blots showed that the chicken actin multigene family was represented by 8 to 10 separate coding loci. The six isolated actin genes corresponded to 7 of 11 genomic EcoRI fragments. Only the alpha-smooth muscle actin gene was shown to be split by an EcoRI site. Thus, in the chicken genome each actin isoform appeared to be encoded by a single gene.


1999 ◽  
Vol 65 (7) ◽  
pp. 2871-2876 ◽  
Author(s):  
Sandra Iurescia ◽  
Andrea M. Marconi ◽  
Daniela Tofani ◽  
Augusto Gambacorta ◽  
Annalisa Paternò ◽  
...  

ABSTRACT The M1 strain, able to grow on β-myrcene as the sole carbon and energy source, was isolated by an enrichment culture and identified as a Pseudomonas sp. One β-myrcene-negative mutant, called N22, obtained by transposon mutagenesis, accumulated (E)-2-methyl-6-methylen-2,7-octadien-1-ol (or myrcen-8-ol) as a unique β-myrcene biotransformation product. This compound was identified by gas chromatography-mass spectrometry. We cloned and sequenced the DNA regions flanking the transposon and used these fragments to identify the M1 genomic library clones containing the wild-type copy of the interrupted gene. One of the selected cosmids, containing a 22-kb genomic insert, was able to complement the N22 mutant for growth on β-myrcene. A 5,370-bp-long sequence spanning the region interrupted by the transposon in the mutant was determined. We identified four open reading frames, named myrA,myrB, myrC, and myrD, which can potentially code for an aldehyde dehydrogenase, an alcohol dehydrogenase, an acyl-coenzyme A (CoA) synthetase, and an enoyl-CoA hydratase, respectively. myrA, myrB, andmyrC are likely organized in an operon, since they are separated by only 19 and 36 nucleotides (nt), respectively, and no promoter-like sequences have been found in these regions. ThemyrD gene starts 224 nt upstream of myrA and is divergently transcribed. The myrB sequence was found to be completely identical to the one flanking the transposon in the mutant. Therefore, we could ascertain that the transposon had been inserted inside the myrB gene, in complete agreement with the accumulation of (E)-2-methyl-6-methylen-2,7-octadien-1-ol by the mutant. Based on sequence and biotransformation data, we propose a pathway for β-myrcene catabolism in Pseudomonas sp. strain M1.


BMC Genomics ◽  
2011 ◽  
Vol 12 (Suppl 1) ◽  
pp. S5 ◽  
Author(s):  
Sara D'Angelo ◽  
Nileena Velappan ◽  
Flavio Mignone ◽  
Claudio Santoro ◽  
Daniele Sblattero ◽  
...  

1999 ◽  
Vol 10 (04) ◽  
pp. 635-643 ◽  
Author(s):  
AGNIESZKA GIERLIK ◽  
PAWEŁ MACKIEWICZ ◽  
MARIA KOWALCZUK ◽  
STANISŁAW CEBRAT ◽  
MIROSŁAW R. DUDEK

Coding sequences of DNA generate Open Reading Frames (ORFs) inside them with much higher frequency than random DNA sequences do, especially in the antisense strand. This is a specific feature of the genetic code. Since coding sequences are selected for their length, the generated ORFs are indirect results of this selection and their length is also influenced by selection. That is why ORFs found in any genome, even much longer ones than those spontaneously generated in random DNA sequences, should be considered as two different sets of ORFs: The first one coding for proteins, the second one generated by the coding ORFs. Even intergenic sequences possess greater capacity for generating ORFs than random DNA sequences of the same nucleotide composition, which seems to be a premise that intergenic sequences were generated from coding sequences by recombinational mechanisms.


2007 ◽  
Vol 73 (5) ◽  
pp. 1612-1621 ◽  
Author(s):  
B. El Yacoubi ◽  
A. M. Brunings ◽  
Q. Yuan ◽  
S. Shankar ◽  
D. W. Gabriel

ABSTRACT Xanthomonas citri pv. citri is a clonal group of strains that causes citrus canker disease and appears to have originated in Asia. A phylogenetically distinct clonal group that causes identical disease symptoms on susceptible citrus, X. citri pv. aurantifolii, arose more recently in South America. Genomes of X. citri pv. aurantifolii strains carry two DNA fragments that hybridize to pthA, an X. citri pv. citri gene which encodes a major type III pathogenicity effector protein that is absolutely required to cause citrus canker. Marker interruption mutagenesis and complementation revealed that X. citri pv. aurantifolii strain B69 carried one functional pthA homolog, designated pthB, that was required to cause cankers on citrus. Gene pthB was found among 38 open reading frames on a 37,106-bp plasmid, designated pXcB, which was sequenced and annotated. No additional pathogenicity effectors were found on pXcB, but 11 out of 38 open reading frames appeared to encode a type IV transfer system. pXcB transferred horizontally in planta, without added selection, from B69 to a nonpathogenic X. citri pv. citri (pthA::Tn5) mutant strain, fully restoring canker. In planta transfer efficiencies were very high (>0.1%/recipient) and equivalent to those observed for agar medium with antibiotic selection, indicating that pthB conferred a strong selective advantage to the recipient strain. A single pathogenicity effector that can confer a distinct selective advantage in planta may both facilitate plasmid survival following horizontal gene transfer and account for the origination of phylogenetically distinct groups of strains causing identical disease symptoms.


2001 ◽  
Vol 357 (3) ◽  
pp. 875-880 ◽  
Author(s):  
Qiang HAO ◽  
Willy J. PEUMANS ◽  
Els J. M. van DAMME

The capacity of IRIP, a type-1 ribosome-inactivating protein (RIP) isolated from the bulbs of Iris hollandica, to bind specific DNA sequences from a mixture of approx. 200bp (average length) fragments of total genomic DNA from Iris genome was studied. Fragments that were preferentially bound by IRIP were enriched by several cycles of affinity binding and PCR, and were cloned and sequenced. The selected DNA fragments do not share conserved sequences, indicating that IRIP does not bind DNA fragments in a strictly sequence-specific manner. According to sequence analysis, most IRIP-bound fragments contain one or more possible free energy-stable hairpin structure(s) in their secondary structure, which may be the basis for recognition between IRIP and these DNA fragments. Some, but not all, DNA fragments moderately lower the RNA N-glycosidase activity of IRIP towards rabbit reticulocyte lysate ribosomes. IRIP does not remove adenines from the binding fragments, which implies that it does not act as a polynucleotide:adenosine glycosidase towards these DNA fragments. The selective binding of IRIP to conspecific DNA fragments is also discussed in view of the novel concept that RIPs may act as DNA-binding proteins with a regulatory activity on gene expression.


1995 ◽  
Vol 41 (3) ◽  
pp. 217-226 ◽  
Author(s):  
Margarita Beatriz Viejo ◽  
Josefina Enfedaque ◽  
Joan Francesc Guasch ◽  
Santiago Ferrer ◽  
Miguel Regué

The gene encoding bacteriocin 28b from Serratia marcescens N28b (bss gene) has been cloned in Escherichia coli and its nucleotide sequence has been determined. The genetic determinants coding for other well-characterized bacteriocins from enterobacteria (colicins) are located in plasmids and they have always been shown to contain a gene responsible for immunity located downstream from the bacteriocin structural gene. In some cases there is another gene located downstream from the immunity gene, which is responsible for bacteriocin release. Analysis of bacteriocin 28b release and the sensitivity to this bacteriocin of E. coli strains harbouring recombinant plasmids containing the bss gene showed that bacteriocin 28b is not released from the cell in these strains and that their phenotypic insensitivity is not associated with any region close to the structural gene. The nucleotide sequence of the region downstream from the bss gene contains two putative open reading frames transcribed in the opposite direction to the bss gene. These open reading frames apparently encode proteins that seem not to be involved in bacteriocin immunity or release. Moreover, a S. marcescens N28b genomic library was screened and no immunity gene was found. Therefore, bacteriocin 28b differs greatly from the bacteriocins from other enterobacteria, and in the following senses it is unique: firstly, the gene encoding bacteriocin 28b seems to be located on the chromosome, and secondly, insensitivity to this bacteriocin in S. marcescens N28b is not associated with the expression of an immunity gene.Key words: bacteriocin, pore-forming colicins, immunity, Serratia marcescens.


2007 ◽  
Vol 189 (16) ◽  
pp. 5792-5802 ◽  
Author(s):  
Takeru Kawasaki ◽  
Shoko Nagata ◽  
Akiko Fujiwara ◽  
Hideki Satsuma ◽  
Makoto Fujie ◽  
...  

ABSTRACT The genomic DNA sequences were determined for two filamentous integrative bacteriophages, φRSS1 and φRSM1, of the phytopathogen Ralstonia solanacearum. The 6,662-base sequence of φRSS1 contained 11 open reading frames (ORFs). In the databases, this sequence showed high homology (95% identity) to the circular double-stranded DNA plasmid pJTPS1 (6,633 bp) isolated from a spontaneously occurring avirulent mutant of R. solanacearum. Two major differences between the two sequences were observed within φRSS1 ORF7, corresponding to pIII, a minor coat protein required for host adsorption, and at the φRSS1 intergenic (IG) region. The 9,004-base sequence of φRSM1 showed 12 ORFs located on the same strand (plus strand) and 2 ORFs on the opposite strand. Compared with Ff-type phages, two insertions are obvious in the φRSM1 replication module. Genomic DNA fragments containing the φRSM integration junctions were cloned and sequenced from φRSM lysogenic strain R. solanacearum MAFF211270. The att core sequence was identified as 5′-TGGCGGAGAGGGT-3′, corresponding to the 3′ end of the serine tRNA (UCG) gene. Interestingly, ORF14, located next to the attP site on the φRSM1 genome, showed high amino acid sequence homology with bacterial DNA recombinases and resolvases, different from XerCD recombinases. attP of φRSS1 is within a sequence element of the IG region.


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