Open AccessShort-Sequence Tandem and Nontandem DNA Repeats and Endogenous Hydrogen Peroxide Production Contribute to Genetic Instability ofStreptococcus pneumoniae
Author(s) -
Christopher D. Pericone,
Deborah Bae,
Mikhail Shchepetov,
Tera L. McCool,
Jeffrey N. Weiser
Publication year - 2002
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.184.16.4392-4399.2002
Subject(s) - biology , tandem repeat , streptococcus pneumoniae , mutation , genetics , guanine , gene , point mutation , dna , hydrogen peroxide , oxidative stress , microbiology and biotechnology , bacteria , biochemistry , nucleotide , genome
Loss-of-function mutations in the following seven pneumococcal genes were detected and analyzed: pspA, spxB, xba, licD2, lytA, nanA, and atpC. Factors associated with these mutations included (i) frameshifts caused by reversible gain and loss of single bases within homopolymeric repeats as short as 6 bases, (ii) deletions caused by recombinational events between nontandem direct repeats as short as 8 bases, and (iii) substitutions of guanine residues caused at an increased frequency by the high levels of hydrogen peroxide (>2 mM) typically generated by this species under aerobic growth conditions. The latter accounted for a frequency as high as 2.8 x 10(-6) for spontaneous mutation to resistance to optochin and was 10- to 200-fold lower in the absence of detectable levels of H2O2. Some of these mutations appear to have been selected for in vivo during pneumococcal infection, perhaps as a consequence of immune pressure or oxidative stress.