Open AccessRedox‐sensing is the basis of photophobic responses in cyanobacteria
Author(s) -
Gabai V.L.,
Glagolev A.N.
Publication year - 1985
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1985.tb00695.x
Subject(s) - plastoquinone , dcmu , photosystem ii , photosynthesis , photochemistry , action spectrum , cyanobacteria , chemistry , electron transfer , biophysics , photosystem i , redox , demethylation , electron transport chain , membrane potential , hydroquinone , biochemistry , biology , thylakoid , chloroplast , organic chemistry , bacteria , genetics , gene expression , dna methylation , gene
Cyanobacteria lack specialized photoreceptors for photophobic responses (PPR), the action spectrum for photosynthesis coinciding with that for PPR. In the presence of 3‐(3′,4′‐dichlorophenyl)‐1,1‐dimethyl urea) (DCMU), which blocks electron transfer prior to plastoquinone (PQ), turning on the light increased the membrane potential, but simultaneously evoked an unusual phobic response, presumably due to oxidation of PQ · H 2 via photosystem I (PS I). White light and the PQ reductant, (DQ · H 2 ), acted as attractants and produced methylation of a 40 kDa membrane peptide. Repellents, an uncoupler, carbonyl cyanide m ‐chlorophenylhydrazone (CCCP), and an oxidant, tetramethyl‐ p ‐hydroquinone(duroquinon) (DQ), caused demethylation. The results are interpreted in the framework of Häder's ‘electron pool hypothesis’, according to which PQ · H 2 level governs PPR. It is further concluded that the same system is the mechanism of pmf‐sensing: