scholarly journals Nucleases Encoded by the Integrated Elements CJIE2 and CJIE4 Inhibit Natural Transformation of Campylobacter jejuni

2009 ◽  
Vol 192 (4) ◽  
pp. 936-941 ◽  
Author(s):  
Esther J. Gaasbeek ◽  
Jaap A. Wagenaar ◽  
Magalie R. Guilhabert ◽  
Jos P. M. van Putten ◽  
Craig T. Parker ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Campylobacter Jejuni ◽  
Genetic Factors ◽  
Natural Transformation ◽  
Homologous Gene ◽  
Dna Uptake ◽  
Dna Arrays ◽  
Genetic Transfer ◽  
Hydrolysis Of ◽  
Hydrolysis Of Dna

ABSTRACT The species Campylobacter jejuni is naturally competent for DNA uptake; nevertheless, nonnaturally transformable strains do exist. For a subset of strains we previously showed that a periplasmic DNase, encoded by dns, inhibits natural transformation in C. jejuni. In the present study, genetic factors coding for DNase activity in the absence of dns were identified. DNA arrays indicated that nonnaturally transformable dns-negative strains contain putative DNA/RNA nonspecific endonucleases encoded by CJE0566 and CJE1441 of strain RM1221. These genes are located on C. jejuni integrated elements 2 and 4. Expression of CJE0566 and CJE1441 from strain RM1221 and a homologous gene from strain 07479 in DNase-negative Escherichia coli and C. jejuni strains indicated that these genes code for DNases. Genetic transfer of the genes to a naturally transformable C. jejuni strain resulted in a decreased efficiency of natural transformation. Modeling suggests that the C. jejuni DNases belong to the Serratia nuclease family. Overall, the data indicate that the acquisition of prophage-encoded DNA/RNA nonspecific endonucleases inhibits the natural transformability of C. jejuni through hydrolysis of DNA.

scholarly journals A DNase Encoded by Integrated Element CJIE1 Inhibits Natural Transformation of Campylobacter jejuni

2009 ◽  
Vol 191 (7) ◽  
pp. 2296-2306 ◽  
Author(s):  
Esther J. Gaasbeek ◽  
Jaap A. Wagenaar ◽  
Magalie R. Guilhabert ◽  
Marc M. S. M. Wösten ◽  
Jos P. M. van Putten ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Molecular Mechanism ◽  
Campylobacter Jejuni ◽  
Natural Transformation ◽  
Dnase Activity ◽  
Comparative Genome Hybridization ◽  
Dna Uptake ◽  
Knockout Mutant ◽  
Gene Encoding ◽  
Plasmid Analysis

ABSTRACT The species Campylobacter jejuni is considered naturally competent for DNA uptake and displays strong genetic diversity. Nevertheless, nonnaturally transformable strains and several relatively stable clonal lineages exist. In the present study, the molecular mechanism responsible for the nonnatural transformability of a subset of C. jejuni strains was investigated. Comparative genome hybridization indicated that C. jejuni Mu-like prophage integrated element 1 (CJIE1) was more abundant in nonnaturally transformable C. jejuni strains than in naturally transformable strains. Analysis of CJIE1 indicated the presence of dns (CJE0256), which is annotated as a gene encoding an extracellular DNase. DNase assays using a defined dns mutant and a dns-negative strain expressing Dns from a plasmid indicated that Dns is an endogenous DNase. The DNA-hydrolyzing activity directly correlated with the natural transformability of the knockout mutant and the dns-negative strain expressing Dns from a plasmid. Analysis of a broader set of strains indicated that the majority of nonnaturally transformable strains expressed DNase activity, while all naturally competent strains lacked this activity. The inhibition of natural transformation in C. jejuni via endogenous DNase activity may contribute to the formation of stable lineages in the C. jejuni population.

Stereochemical course of hydrolysis of DNA by exonuclease I from Escherichia coli

Biochemistry ◽  
1985 ◽  
Vol 24 (8) ◽  
pp. 2072-2076 ◽  
Author(s):  
Richard S. Brody ◽  
Kevin G. Doherty
Keyword(s):  
Escherichia Coli ◽  
Exonuclease I ◽  
Hydrolysis Of ◽  
Hydrolysis Of Dna

scholarly journals Natural Transformation of Campylobacter jejuni Requires Components of a Type II Secretion System

2003 ◽  
Vol 185 (18) ◽  
pp. 5408-5418 ◽  
Author(s):  
Rebecca S. Wiesner ◽  
David R. Hendrixson ◽  
Victor J. DiRita
Keyword(s):  
Campylobacter Jejuni ◽  
Natural Transformation ◽  
Bacterial Species ◽  
Type Ii Secretion ◽  
Dna Uptake ◽  
Type Ii ◽  
Secretion Systems ◽  
Dna Transport ◽  
Type Iv ◽  
Type Ii Secretion System

ABSTRACT The human pathogen Campylobacter jejuni is one of more than 40 naturally competent bacterial species able to import macromolecular DNA from the environment and incorporate it into their genomes. However, in C. jejuni little is known about the genes involved in this process. We used random transposon mutagenesis to identify genes that are required for the transformation of this organism. We isolated mutants with insertions in 11 different genes; most of the mutants are affected in the DNA uptake stage of transformation, whereas two mutants are affected in steps subsequent to DNA uptake, such as recombination into the chromosome or in DNA transport across the inner membrane. Several of these genes encode proteins homologous to those involved in type II secretion systems, biogenesis of type IV pili, and competence for natural transformation in gram-positive and gram-negative species. Other genes identified in our screen encode proteins unique to C. jejuni or are homologous to proteins that have not been shown to play a role in the transformation in other bacteria.

scholarly journals “Take It or Leave It”—Factors Regulating Competence Development and DNA Uptake in Campylobacter jejuni

2021 ◽  
Vol 22 (18) ◽  
pp. 10169
Author(s):  
Julia C. Golz ◽  
Kerstin Stingl
Keyword(s):  
Campylobacter Jejuni ◽  
Natural Transformation ◽  
Genetic Material ◽  
Competence Development ◽  
Dna Uptake ◽  
State Transformation ◽  
Sustained Reduction ◽  
Reduction Strategies ◽  
Uptake Assay ◽  
Microaerobic Conditions

Campylobacter jejuni has a large adaptive potential due to enormous genetic exchange. Factors regulating natural transformation in this food-borne pathogen are largely unknown but of interest for the application of sustained reduction strategies in the food-processing industry. Using a single cell DNA uptake assay, we visualized that recognition of methylated C. jejuni DNA was essential for the first step of DNA uptake into a DNase resistant state. Transformation rates using a resistance marker correlated with the fraction of competent bacteria, harboring one to maximally four locations of active DNA uptake, not necessarily being located at the cell pole. Competence developed with rising pH between 6.5 and 7.5 under microaerobic conditions and was nearly insensitive towards growth temperatures between 32 °C and 42 °C, CO2 concentrations ranging from 0 to 50% and growth rates. However, competence development was abolished at pH 5 or under aerobic stress conditions, in which the bacteria ceased growth but fully survived. The DNA uptake machinery in competent bacteria shut down at slightly acidic pH and was reversibly switched on upon neutralization. It was dependent on the proton motive force and, in contrast to competence development, slightly enhanced under aerobic conditions. The results suggest that natural transformation in C. jejuni occurs in the neutral and microaerobic intestinal environment for enhanced genetic diversity and pre-adaption before host switch. In addition, highly competent bacteria might be shed into the environment, still able to acquire genetic material for increased survival.

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