Isolation and characterization of a UV-sensitive mutator (mutB1) mutant of Haemophilus influenzae

Abstract

The mutBI mutant of Haemophilus influenzae is very sensitive to UV radiation but only slightly sensitive to methylmethane sulfonate or N-methyl-N'-nitro-N-nitrosoguanidine. Cultures of mutBI cells contain high numbers of spontaneous mutants and show hypermutability after exposure to the latter mutagen. Normally high-efficiency transforming markers, as well as low-efficiency ones, transform mutBI recipients at similarly low efficiencies. Significant host cell reactivation was observed when mutBI cells were exposed to UV-damaged phage; however, these mutants showed a decrease in phage recombination. This mutant did not degrade its DNA following exposure to UV. It is speculated that the mutBI mutation is similar to the Escherichia coli uvrD mutation.

Functional characterization of UvrD helicases from Haemophilus influenzae and Helicobacter pylori

“…Inactivation of uvrD in Neisseria meningitides leads to increases in the frequency of phase variation within mononucleotide repeat tracts [25]. The uvrD null mutant of Haemophilus influenzae is sensitive to UV radiation, exhibits reduced levels of host-cell reactivation and decreased phage recombination [26]. In another study, inactivation of Haemophilus influenzae uvrD led to a two-fold increase in spontaneous mutation resulting in rifampicin-resistance and a three-fold increase in rates of pilus phase variation due to the destabilization of long dinucleotide repeat tracts [27].…”

Cloning and characterization of the Haemophilus influenzae mutB gene

“…Host cell reactivation. We have reported that H. influenzae mutBI cells do not show host cell reactivation (25). We have now studied this phenomenon for both H. influenzae phage HP1 and phage lambda by using repair-deficient hosts that carried mutB or uvrD plasmids.…”