Natural transformation of helicobacter pylori involves the integration of short DNA fragments interrupted by gaps of variable size.
Helicobacter pylori are gram-negative bacteria notable for their high level of genetic diversity and plasticity, features that may play a key role in the organism's ability to colonize the human stomach. Homeologous natural transformation, a key contributor to genomic diversification, has been well-described for H. pylori. To examine the mechanisms involved, we performed restriction analysis and sequencing of recombination products to characterize the length, fragmentation, and position of DNA imported via natural transformation. Our analysis revealed DNA imports of small size (1,300 bp, 95% confidence limits 950-1850 bp) with instances of substantial asymmetry in relation to selectable antibiotic-resistance markers. We also observed clustering of imported DNA endpoints, suggesting a possible role for restriction endonucleases in limiting recombination length. Additionally, we observed gaps in integrated DNA and found evidence suggesting that these gaps are the result of two or more separate strand invasions. Taken together, these observations support a system of highly efficient short-fragment recombination involving multiple recombination events within a single locus.
Lin
Edward A
EA
Department of Medicine, New York University School of Medicine, New York, New York, United States of America. edward.lin@med.nyu.edu
Zhang
Xue-Song
XS
Levine
Steven M
SM
Gill
Steven R
SR
Falush
Daniel
D
Blaser
Martin J
MJ
D004269:DNA, Bacterial / Q000235:genetics*; D004352:Drug Resistance, Microbial / Q000235:genetics; D016480:Helicobacter pylori / Q000235:genetics*; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping; D014169:Transformation, Bacterial / Q000235:genetics*
D004269:DNA, Bacterial