RecA Expression in Response to Solar UVR in the Marine Bacterium Vibrio natriegens

Abstract

Solar ultraviolet radiation may produce daily stress on marine and estuarine communities as cells are damaged and repair that damage. Reduction in the earth's stratospheric ozone layer has increased awareness of the potential effects that ultraviolet radiation may have in the environment, including how marine bacteria respond to changes in solar radiation. We examined the use of the bacterial RecA protein as an indicator of the potential of bacteria to repair DNA damage caused by solar UV irradiation using the marine bacterium Vibrio natriegens as a model. RecA is universally present in bacteria and is a regulator protein for the so-called Dark Repair Systems, which include excision repair, postreplication recombinational repair, and mutagenic or SOS repair. Solar UVB and UVA both reduced V. natriegens viability in seawater microcosms. After exposure to unfiltered solar radiation or radiation in which UVB was blocked, survival dropped below 1%, whereas visible light from which UVA and UVB had been filtered had no effect on survival. Using a RecA-specific antibody for detection, RecA protein was induced by solar radiation in a diel pattern in marine microcosms conducted in the Gulf of Mexico. Peak induction was observed at dusk each day. Although RecA expression was correlated with the formation of UVB-induced cyclobutyl pyrimidine dimers, longer wavelength UVA radiation also induced recA gene expression. Our results demonstrate that RecA-regulated, light-independent repair is an important component in the ability of marine bacteria to survive exposure to solar ultraviolet radiation and that RecA expression is a useful monitor of bacterial repair after exposure to solar UVR.

Quantification of recA gene expression as an indicator of repair potential in marine bacterioplankton communities of Antarctica

“…This led to heightened recA-gene expression in late afternoonearly evening. These data agree with our earlier studies (Jeffrey et al 1996b, Lyons et al 1997, Booth et al 2001 demonstrating that un-repaired thymine dimers remaining at sunset decrease and return to background levels by sunrise. Taken together, these observations suggest that unrepaired lesions are corrected by dark repair in marine bacterioplankton.…”

“…We have previously investigated RecA response in the marine bacterium Vibrio natriegens in Gulf of Mexico microcosms (Booth et al 2001). Similar recA-induction patterns were observed with V. natriegenes as were observed with RM11001.…”

“…However, induction levels in microcosms exposed to only UV-A and PAR light were significantly lower than the levels detected in response to full sunlight. No induction of RecA was observed in the dark control or when the cells were exposed to only PAR.We have previously investigated RecA response in the marine bacterium Vibrio natriegens in Gulf of Mexico microcosms (Booth et al 2001). Similar recA-induction patterns were observed with V. natriegenes as were observed with RM11001.…”

Identification of Outer Membrane Proteins Altered in Response to UVC-Radiation in Vibrio parahaemolyticus and Vibrio alginolyticus

“…This absorption creates damage in the DNA by altering the nucleotide base pairing, thereby creating new linkages between adjacent nucleotides on the same DNA strand [6]. Several investigators have determined the effects of UV radiation on the inhibition of growth [7] and damage of protein, RNA, and DNA for Vibrio [8,9]. All these effects have been related directly or indirectly to genomic damage arising out of primary photochemical changes in nucleic acids.…”

Ultraviolet radiation sensitivity in cave bacteria: evidence of adaptation to the subsurface?

“…The excision repair system removes and replaces lesions with undamaged monomers prior to replication, while the recombination or post-replication repair system repairs gaps in daughter strands after DNA synthesis. Finally, the SOS system, mediated by the recA gene, reduces the fidelity of DNA polymerase III so it bypasses damaged nucleotides (Booth et al, 2001;Miller 2000). In addition, bacterial DNA can be repaired using the light-dependent repair mechanisms, which are initiated by exposure to UVR.…”