mosaic dna imports with interspersions of recipient sequence after natural transformation of helicobacter pylori马赛克dna进口布置的接受者序列后幽门螺杆菌的自然转换.pdfVIP

Mosaic DNA Imports with Interspersions of Recipient Sequence after Natural Transformation of Helicobacter pylori 1. 1. 2 3 1¤ Stefan Kulick , Claudia Moccia , Xavier Didelot , Daniel Falush , Christian Kraft , Sebastian Suerbaum1* 1 Institute of Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hannover, Germany, 2 Department of Statistics, University of Warwick, Coventry, United Kingdom, 3 Environmental Research Institute, University College Cork, Cork, Ireland Abstract Helicobacter pylori colonizes the gastric mucosa of half of the human population, causing gastritis, ulcers, and cancer. H. pylori is naturally competent for transformation by exogenous DNA, and recombination during mixed infections of one stomach with multiple H. pylori strains generates extensive allelic diversity. We developed an in vitro transformation protocol to study genomic imports after natural transformation of H. pylori. The mean length of imported fragments was dependent on the combination of donor and recipient strain and varied between 1294 bp and 3853 bp. In about 10% of recombinant clones, the imported fragments of donor DNA were interrupted by short interspersed sequences of the recipient (ISR) with a mean length of 82 bp. 18 candidate genes were inactivated in order to identify genes involved in the control of import length and generation of ISR. Inactivation of the antimutator glycosylase MutY increased the length of imports, but did not have a significant effect on ISR frequency. Overexpression of mutY strongly increased the frequency of ISR, indicating that MutY, while not indispensable for ISR formation, is part of at least one ISR-generating pathway. The form