201. Phenotypes of a Naturally Defective recBAllele in Neisseria meningitidisClinical Isolates
- Author
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Salvatore, Paola, Bucci, Cecilia, Pagliarulo, Caterina, Tredici, Maurizio, Colicchio, Roberta, Cantalupo, Giuseppina, Bardaro, Marcellino, Del Giudice, Luigi, Massardo, Domenica R., Lavitola, Alfredo, Bruni, Carmelo B., and Alifano, Pietro
- Abstract
ABSTRACTNeisseria meningitidisstrains belonging to the hypervirulent lineage ET-37 and several unrelated strains are extremely UV sensitive. The phenotype is consequent to the presence of a nonfunctional recBET-37allele carrying multiple missense mutations. Phenotypic analysis has been performed with congenic meningococcal strains harboring either the wild-type recBallele or the recBET-37allele. Congenic recBET-37meningococci, in addition to being sensitive to UV, were defective both in repair of DNA lesions induced by UV treatment and, partially, in recombination-mediated transformation. Consistently, the wild-type, but not the recBET-37, allele was able to complement the Escherichia coli recB21mutation to UV resistance and proficiency in recombination. recBET-37meningococci did not exhibit higher frequencies of spontaneous mutation to rifampin resistance than recB-proficient strains. However, mutation rates were enhanced following UV treatment, a phenomenon not observed in the recB-proficient counterpart. Interestingly, the results of PCR-based assays demonstrated that the presence of the recBET-37allele considerably increased the frequency of recombination at the pilin loci. The main conclusion that can be drawn is that the presence of the defective recBET-37allele in N. meningitidisisolates causes an increase in genetic diversity, due to an ineffective RecBCD-dependent DNA repair and recombination pathway, and an increase in pilin antigenic variation.
- Published
- 2002
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