Evidence for repair of ultraviolet-induced damage inCystobacter species (Myxobacterales)

In the ultraviolet (UV)-mutable bacterium, Myxococcus xanthus, dose response curves for the induction of rifampicin-resistant (Rifr) mutants were compared with dose response curves for Weigle(W)-reactivation of the UV-irradiated phage Mx4 at a phage survival of 5 X 10(-6). In most strains examined, including a uvr mutant, these curves are largely similar. Unexpectedly the UV-sensitive strain M. xanthus Bt, which is unable to perform W-reactivation, is nevertheless UV-mutable. This result may indicate that the repair pathway involved in phage reactivation is only partly responsible for UV-mutagenesis or alternatively is not able to act on phage DNA in M. xanthus Bt cells. N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) treatment of M. xanthus cells also results in marked W-reactivation of the UV-irradiated phage Mx4 at the same survival of 5 X 10(-6). The MNNG-stimulated phage reactivation is of the same order of magnitude as the UV-stimulated phage reactivation. Also the dose response curves for the induction of Rifr mutants by MNNG and the MNNG-stimulated phage reactivation are quite similar. This coincidence may indicate that misrepair mutagenesis is involved in both UV and MNNG-mutagenesis. It is suggested that M. xanthus is a useful organism with which to study misrepair mutagenesis in bacteria.

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Host‐cell Reactivation and Weigle Reactivation of Ultraviolet‐irradiated Myxococcus Xanthus Phages

Grimm¹,

Herdrich²

1980

Photochem & Photobiology

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Abstract— Myxococcus xanthus DZ1, and particularly M. xanthus B, show a phase variation resulting in tan and yellow pigmented colonies. M. xanthus XK is stable and yellow colonies occur only as rare mutants. The various M. xanthus strains exhibit different resistances to short wave UV. With the exception of M. xanthus XK the yellow types are more resistant than the tan types with the greatest difference found in M. xanthus B. This is probably partly responsible for the enrichment of yellow types during UV irradiation of M. xanthus B tan. By ICR mutagenesis a uvr mutant of Af. xanthus XK was isolated. Using this mutant it could be demonstrated that all strains, whether yellow or tan pigmented, are able to host‐cell reactivate UV irradiated phages Mxl and Mx4. The repair efficiency for irradiated Mxl is approximately 71 to 79% at a survival level of 10%. Weigle reactivation of phage Mx4 occurs in Af. xanthus XK and DZ1. The effect is most pronounced in M. xanthus XK with a repair efficiency of 44% at 1% survival. The uvr‐1 mutant is also able to W‐reactivate phage Mx4. Only the yellow phenotype of M. xanthus B is able to W reactivate the irradiated phage Mx4 ts27htf‐lhrm‐l with a similar efficiency to M. xanthus XK. M. xanthus B tan is therefore probably blocked in an inducible repair pathway. The phage Mx 1 is W‐reactivated by none of the M. xanthus strains used.

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Evidence for repair of ultraviolet-induced damage inCystobacter species (Myxobacterales)

Cited by 3 publications

References 15 publications

Myxobacteria

Myxobacteria

Misrepair mutagenesis in Myxococcus xanthus: Induction of rifampicin-resistant mutants by N-methyl-N′-nitro-N-nitrosoguanidine and ultraviolet-irradiation

Host‐cell Reactivation and Weigle Reactivation of Ultraviolet‐irradiated Myxococcus Xanthus Phages

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