Photoaffinity labelling of the β-methoxyacrylate binding site in bovine heart mitochondrial cytochrome bc1 complex

Mitochondrial cytochrome b: evolution and structure of the protein

“…been determined, a number of overlapping designations of the pre&cted structural elements of the protern have accumulated This is parhcularly the case for the putatwe transmembrane hehces, which were mltrolly deslgnated with roman numerals [22,23] Later, either letters [8,18,24,25] or arabic numbers [9,19,26] have been used concomitantly with the roman numerals [10][11][12]21,27] Hereto, we shall conform to the nomenclature proposed by Crofts [24,28] m which the hkely transmembrane hehces are defined by capital letters and the extramembrane loops by the lower case letters of the behces connected by them ub~qumone mteracts w~th cytochrome b t n the reductase enzyme The original designation of such sites as centers i (proton input) and o (proton output) proposed wlthm the Q-cycle mechanism [13][14][15] is probably the most widely used, and we shall conform to it Other common nomenclatures of the qumone centers are Q1, Q m , Q c , Qr o r Q n for center i and Qo Qout, Qz or Qp for center o [6][7][8][9][10][17][18][19][24][25][26][27][28] …”

“…The techniques of sequence analysis that have been discussed thus far are of limited value for understandlng the details of the redox functton of cytochrome b since no atomic structure is available, although crystallzation of the beef bc I complex has been reported [110,111] Complementary mformatlon is indispensable for refinements of the present models of mltochondrlal cytochrome b structure This mformation is also important for understanding the functton of structural features that are conserved [8,18,19,65,68] Important relationships can be estabhshed indirectly between the structural features of cytochrome b and the sensitivity of the bc I complex to its lnhlbltors [5,6,8,9,12,19,[24][25][26][27][28]36,39,44,46,68,73,80,81,90] T h i s IS possible because the inhlbitors of the b c 1 complex bind directly to cytochrome b as evidenced by photoafflmty labeling [17], changes in spectroscopic properties [80,81,[112][113][114][115] and genetic analysis [4][5][6]19,24,26,36,68,…”

Natural products in plant protection

“…These analogues of strobilurins and oudemansins are produced by several genera of small agarics such as Strobilurus and Oudemansiella. These antibiotics have the I~-methoxyacrylate moiety in common and proved to be unique inhibitors of mitochondrial respiration by binding to cytochrome B (Mansfield and Wiggins, 1990). Practical application of the antibiotics is not possible, because they can not be produced on a large scale, are relatively volatile and very instable (Godwin et al, 1992).…”

Interactions of the myxothiazol and mucidin toxophores with cytochrome b

“…As these compounds compete for the same binding site [2,3] there must be within that site amino acids which can accommodate and bind both of these toxophores. DNA-sequencing of the cytochrome b genes from yeast mutants resistant to methoxyacrylate inhibitors has identified three regions where mutations occur; glycine-137, asparagine-256 and leucine-276 [4].…”