TY - JOUR
T1 - A novel prokaryotic UVB photoreceptor in the cyanobacterium Chlorogloeopsis PCC 6912
AU - Portwich, Anne
AU - Garcia-Pichel, Ferran
PY - 2000/4/1
Y1 - 2000/4/1
N2 - We present evidence for the presence and nature of a UVB-specific photoreceptor in the cyanobacterium Chlorogloeopsis PCC 6912. The photoreceptor mediates at least the photosensory induction of mycosporine-like amino acid (MAA) synthesis. Because MAA synthesis in this organism can also be induced under salt stress, we could distinguish between the photosensory and the purely biochemical requirements of MAA synthesis. Neither visible light nor UV radiation was necessary for the biosynthetic process, thus indicating that the UVB (280-320 nm) dependence of biosynthesis is based on a UV photosensory capacity of the organism. An action spectrum of the MAA synthesis showed a distinct peak at 310 nm tailing down into the UVA (320-400 nm) region with no detected activity above 340 nm. We found that radiation below 300 nm caused significant inhibition of synthesis of MAAs indicating that the action spectrum at these wavelengths may not have been satisfactorily resolved. We propose that a pterin is a good candidate for a photoreceptor chromophore as (1) reduced pterins present absorption spectra congruent with the action spectrum obtained; and (2) an inhibitor of the biosynthetic pathway of pterins and an antagonist of excited states of pterins, both depressed the photosensory efficiency of induction but not its chemosensory efficiency.
AB - We present evidence for the presence and nature of a UVB-specific photoreceptor in the cyanobacterium Chlorogloeopsis PCC 6912. The photoreceptor mediates at least the photosensory induction of mycosporine-like amino acid (MAA) synthesis. Because MAA synthesis in this organism can also be induced under salt stress, we could distinguish between the photosensory and the purely biochemical requirements of MAA synthesis. Neither visible light nor UV radiation was necessary for the biosynthetic process, thus indicating that the UVB (280-320 nm) dependence of biosynthesis is based on a UV photosensory capacity of the organism. An action spectrum of the MAA synthesis showed a distinct peak at 310 nm tailing down into the UVA (320-400 nm) region with no detected activity above 340 nm. We found that radiation below 300 nm caused significant inhibition of synthesis of MAAs indicating that the action spectrum at these wavelengths may not have been satisfactorily resolved. We propose that a pterin is a good candidate for a photoreceptor chromophore as (1) reduced pterins present absorption spectra congruent with the action spectrum obtained; and (2) an inhibitor of the biosynthetic pathway of pterins and an antagonist of excited states of pterins, both depressed the photosensory efficiency of induction but not its chemosensory efficiency.
UR - http://www.scopus.com/inward/record.url?scp=0034175441&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034175441&partnerID=8YFLogxK
U2 - 10.1562/0031-8655(2000)071<0493:ANPUPI>2.0.CO;2
DO - 10.1562/0031-8655(2000)071<0493:ANPUPI>2.0.CO;2
M3 - Article
C2 - 10824604
AN - SCOPUS:0034175441
SN - 0031-8655
VL - 71
SP - 493
EP - 498
JO - Photochemistry and photobiology
JF - Photochemistry and photobiology
IS - 4
ER -