PHOTOREACTIVATION OF KILLING IN STREPTOMYCES: ACTION SPECTRA AND KINETIC STUDIES*

Abstract

An action spectrum was obtained for photoreactivation of killing (PR) of Streptomyces griseus conidia. This spectrum shows a major peak around 436 nm, originally observed by A. Kelner, and a secondary peak at 3 I3 nm not previously reported. The rate of PR shows a strong dependence upon temperature and dose rate of the PR light at 436 nm, but this decreases to only a slight dependence upon these parameters at 3 I3 nm. These findings suggested that PR at 436 nm in this organism is of the usual photoenzymatic type, but that PR at 313 nm might be of a different kind.A mutant (PHR-I) of S . griseus was found that shows only a narrow range of PR (roughly 3 10-400 nm) with a single peak at 3 I3 nm. The PR efficiency was lower than for wild type and the PR sector not greater than one-half that of wild type. This PR shows no temperature dependence. Essentially similar behavior was observed with wild-type Streptomyces coelicolor. These findings show that at least some of the PR at 3 I3 nm is a separable phenomenon. It is therefore unlikely to involve a mechanism identical to that at 436 nm.The nature of PR at 3 I3 nm in Streptomyces is not known. If it is enzymatic, it is remarkable in having little or no dependence upon temperature and dose rate. Absence of photoprotection and liquid-holding recovery indicate that it is not indirect PR. Some of it (that part exhibited by S. griseus PHR-I and S. coelicolor) might result from a direct photochemical action on DNA. I N T R O D U C T I O NPH~TOREACTIVATION (PR) was discovered in Streptomyces griseus by Kelner [ 11, who observed that the PR rate showed a strong dependence upon temperature during PR and that dose-rate-saturation effects were observed (failure of Bunsen-Roscoe reciprocity of time and dose rate). Early workers quickly concluded that PR was mediated primarily by an enzyme that acted upon DNA. PR enzyme activity has now been found in extracts from several sources, and the enzyme from baker's yeast has been considerably purified [2]. In this paper we shall call this enzymatic photoreactivation 'Type I PR'. In Escherichia coli, Type 1 PR (believed to be the only type in E. coli B,-,[3]) is characterized by efficient PR in the range 320-440 nm, with a peak activity around 385 nm (see Fig. 8). The same is true for the yeast PR enzyme. In Neurosporu crussu, however, the range of efficient PR is slightly broader, and shows a peak around 400 nm (Fig. 8).In 1965, Jagger and StafFord[4] presented evidence for a second kind of photoreactivation in E. coli B. We shall call this 'Type I I PR'. It is characterized by a much narrower wavelength range (3 10-380 nm) with a peak of activity around 340 nm. That Type I I PR differs from Type I PR is demonstrated by (1) a complete lack of dose-rate dependence and only slight temperature dependence[4], (2) its occurrence [4] in a strain lacking PR-enzyme activity in cell extracts [5,6], and (3) the fact that this kind of PR

Photoreactivation in an archaeon from geothermal environments

“…Forms of photoreactivation have been reported which do not appear to involve DNA photolyase, but these tend to be inefficient and to occur only at short wavelengths (Jagger et al, 1970). Results of the present study therefore provide physiological evidence of the light-dependent enzymic repair of deleterious, UV-induced lesions of the S. acidocaldarius chromosome.…”

“…Streptomyces griseus photolyase, in contrast, has an 8-hydroxy-5-deazaflavin derivative; the absorbance and action spectra of this photolyase each have a single maximum near 445 nm (Jagger et al, 1970;Sancar & Sancar, 1988 (Jagger et al, 1970;Harm, 1980;Kiener et al, 1985;Eker et al, 1991). Although resolution of its precise shape is limited by scatter in the values measured, the action spectrum of photoreactivation for UV-treated S. acidocaldarius cells appears significantly broader than either of the two classical types described above.…”

Models for the solution state structure of the (6–4) photoproduct of thymidylyl‐(3′ → 5′)‐thymidine derived via a distance‐ and angle‐constrained conformation search procedure

“…These planar pyrimidinone-containing structures are to be contrasted with Rao and Kollman's TpC, diastereomeric (6-4) structures, which had highly bent pyrimidone rings with endocyclic angles ranging from 5°-200. 23 By way of comparison, the 12 carbon bridge present in the (6-4) photoproduct is four atoms longer than the highly strained [8] para~yclophane.~~ The benzene ring of this cyclophane does not have any endocyclic torsion angles greater than l l " , suggesting that a highly bent pyrimidone ring in the (6-4) product is unlikely, even when part of duplex DNA. The highly bent pyrimidinone structures that were obtained in the previous modeling study might be attributed to the model-building strategy used.…”

Personal reflections on monchroators and action spectra for photoreactivation

“…1, open triangles), show a higher PR than can be accounted for by either indirect PR or by photoenzymatic PR. A possible solution to this problem came from some of our work at Dallas in 1970 with strains of Streptomyces [15,17,18]. Fig.…”