title: Re-evaluation of the side effects of cytochrome b6f inhibitor dibromothymoquinone on photosystem II excitation and electron transfer.
abstract: Dibromothymoquinone (DBMIB) has been used as a specific inhibitor of plastoquinol oxidation at the Q0 binding site of the cytochrome b6f complex for 40 years. It is thought to suppress electron transfer between photosystem (PS) II and I, as well as cyclic electron transfer around PSI. However, DBMIB has also been reported to act as a quencher of chlorophyll excited states. In this study, we have re-evaluated the effects of DBMIB on chlorophyll excited states and PSII photochemistry. The results show that DBMIB significantly quenches the chlorophyll excited states of PSII antenna even at low concentration (from 0.1 μM), lowering the effective excitation rate of the actinic light. It also acts as a potent PSII electron acceptor retarding the reduction of the plastoquinone pool with almost maximal potency at 2 μM. Altogether, these results suggest that experiments using DBMIB can easily be misinterpreted and stress on the importance of taking into account all these side effects that occur in the same range of DBMIB concentration used for inhibition of plastoquinol oxidation (1 μM).
authors: Groupe de Recherche en Biologie Végétale, Département de Chimie-Biologie, Université du Québec à Trois-Rivières, C.P. 500, Trois-Rivières, QC, G9A 5H7, Canada.
authors: Ahmed
authors: A
authors: Belatik
authors: David
authors: D
authors: Joly
authors: Surat
authors: S
authors: Hotchandani
authors: Robert
authors: R
authors: Carpentier
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D045346:Cytochrome b6f Complex / Q000037:antagonists & inhibitors* / Q000378:metabolism; D003991:Dibromothymoquinone / Q000494:pharmacology*; D004579:Electron Transport / Q000187:drug effects; D004583:Electrons; D008163:Luminescent Measurements; D062105:Molecular Docking Simulation; D010100:Oxygen / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013057:Spectrum Analysis; D018724:Spinacia oleracea / Q000187:drug effects* / Q000378:metabolism*; D013696:Temperature; D020524:Thylakoids / Q000187:drug effects / Q000378:metabolism
chemical_list: D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D003991:Dibromothymoquinone; D045346:Cytochrome b6f Complex; D010100:Oxygen; D000077194:Chlorophyll A
references: Photosynth Res. 1996 May;48(1-2):117-26
references: 24271292
references: FEBS Lett. 1973 Jan 15;29(2):153-5
references: 4146296
references: Photosynth Res. 2000;63(3):195-208
references: 16228430
references: Photosynth Res. 2005 Jun;84(1-3):161-6
references: 16049769
references: Photosynth Res. 2005 Jun;84(1-3):107-12
references: 16049762
references: Biochim Biophys Acta. 2003 Jun 5;1604(2):115-23
references: 12765768
references: Biochim Biophys Acta. 2006 Nov;1757(11):1547-56
references: 17064657
references: Photosynth Res. 2005 Jun;84(1-3):167-72
references: 16049770
references: Z Naturforsch B. 1970 Oct;25(10):1157-9
references: 4394873
references: Biochim Biophys Acta. 1975 Jan 31;376(1):105-15
references: 1125215
references: Biochim Biophys Acta. 1999 May 26;1412(1):1-28
references: 10354490
references: Biochim Biophys Acta. 2005 Sep 30;1709(3):203-13
references: 16137641
references: Photosynth Res. 2007 May;92(2):217-24
references: 17647089
references: Planta. 2005 Dec;223(1):114-133
references: 16411287
references: Eur J Biochem. 1973 Aug 1;37(1):185-92
references: 4729426
references: J Exp Bot. 2003 Nov;54(392):2419-30
references: 14565948
references: Nat Struct Mol Biol. 2009 Mar;16(3):334-42
references: 19219048
references: Methods Mol Biol. 2004;274:229-48
references: 15187283
references: Biochim Biophys Acta. 2003 Sep 30;1606(1-3):147-52
references: 14507435
references: J Photochem Photobiol B. 2011 Jul-Aug;104(1-2):1-8
references: 21507673
references: Methods Mol Biol. 2011;684:321-5
references: 20960139
references: J Theor Biol. 2003 Feb 21;220(4):469-503
references: 12623282
references: Arch Biochem Biophys. 1979 Oct 1;197(1):52-6
references: 543724
references: Photochem Photobiol. 2012 Jan-Feb;88(1):67-75
references: 21988107
references: Planta. 2005 Jun;221(4):567-79
references: 15688225
references: PLoS One. 2010 May 25;5(5):e10821
references: 20520829
references: Biochim Biophys Acta. 2005 Feb 17;1706(3):250-61
references: 15694353
references: FEBS J. 2006 Oct;273(20):4770-7
references: 16987315
references: Biochim Biophys Acta. 2011 Sep;1807(9):1177-84
references: 21640068
references: Biochim Biophys Acta. 2007 Jun;1767(6):458-71
references: 17428439