Identification of tenuazonic acid as a novel type of natural photosystem II inhibitor binding in Q(B)-site of Chlamydomonas reinhardtii.
Tenuazonic acid (TeA) is a natural phytotoxin produced by Alternaria alternata, the causal agent of brown leaf spot disease of Eupatorium adenophorum. Results from chlorophyll fluorescence revealed TeA can block electron flow from Q(A) to Q(B) at photosystem II acceptor side. Based on studies with D1-mutants of Chlamydomonas reinhardtii, the No. 256 amino acid plays a key role in TeA binding to the Q(B)-niche. The results of competitive replacement with [(14)C]atrazine combined with JIP-test and D1-mutant showed that TeA should be considered as a new type of photosystem II inhibitor because it has a different binding behavior within Q(B)-niche from other known photosystem II inhibitors. Bioassay of TeA and its analogues indicated 3-acyl-5-alkyltetramic and even tetramic acid compounds may represent a new structural framework for photosynthetic inhibitors.
Chen
Shiguo
S
Weed Research Laboratory, Nanjing Agricultural University, Nanjing 210095, China.
Xu
Xiaoming
X
Dai
Xinbin
X
Yang
Chunlong
C
Qiang
Sheng
S
D000595:Amino Acid Sequence; D000818:Animals; D001280:Atrazine / Q000737:chemistry; D016227:Benzoquinones / Q000378:metabolism; D001665:Binding Sites; D001667:Binding, Competitive; D016825:Chlamydomonas reinhardtii / Q000187:drug effects / Q000201:enzymology*; D004579:Electron Transport / Q000187:drug effects; D008969:Molecular Sequence Data; D009154:Mutation; D010100:Oxygen / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics; D011487:Protein Conformation; D011760:Pyrrolidinones / Q000737:chemistry / Q000494:pharmacology; D013720:Tenuazonic Acid / Q000378:metabolism / Q000633:toxicity*; D020524:Thylakoids / Q000187:drug effects
D016227:Benzoquinones; D045332:Photosystem II Protein Complex; D011760:Pyrrolidinones; C004532:quinone; C009435:tetramic acid; D013720:Tenuazonic Acid; D001280:Atrazine; D010100:Oxygen