Molecular characterization of two spontaneous antimycin A resistant mutants of Rhodospirillum rubrum

Uhrig, Joachim F.; Jakobs, Christiane U.; Majewski, Christoph; Trebst, Achim

doi:10.1016/0005-2728(94)90008-6

Cited by 7 publications

(5 citation statements)

References 29 publications

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“…The O13 of the methoxy group is 2.8 Å from the OG of Ser 205 . The two isoprenoid repeats that were visible in the electron density are in contact with residues Phe 18 , Ser 35 , Gly 38 , Met 190 , Leu 197 , and the b H heme.…”

Section: Resultsmentioning

confidence: 95%

“…Antimycin A resistance mutations in the bc 1 complex from various species were reported; when mapped onto the atomic model of cyt. b with bound antimycin A, all of them were located in the immediate vicinity of the inhibitor binding pocket (Table , Figure A) ( − ). Mutations 1 and 2 in Table each cause the loss of two strong H-bonding interactions important to inhibitor binding.…”

Section: Discussionmentioning

confidence: 99%

“…27 , Trp31 , Asn32 , and Phe 224 are in contact with the formyl group of the 3-FASA; at the entrance of the Q i pocket, the dilactone ring makes contacts with Phe 28 , Gly38 , Leu 197 , and the b H heme. The 1-methyl butanoate tail is near the entrance of the Q i pocket in contact with Met 194 and Met 190 , whereas the disordered hexyl tail remains outside the Q i pocket with no contact with the cyt.…”

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confidence: 99%

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Structural Basis for the Quinone Reduction in thebc₁Complex: A Comparative Analysis of Crystal Structures of Mitochondrial Cytochromebc₁with Bound Substrate and Inhibitors at the Q_iSite^,

et al. 2003

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Cytochrome bc(1) is an integral membrane protein complex essential to cellular respiration and photosynthesis. The Q cycle reaction mechanism of bc(1) postulates a separated quinone reduction (Q(i)) and quinol oxidation (Q(o)) site. In a complete catalytic cycle, a quinone molecule at the Q(i) site receives two electrons from the b(H) heme and two protons from the negative side of the membrane; this process is specifically inhibited by antimycin A and NQNO. The structures of bovine mitochondrial bc(1) in the presence or absence of bound substrate ubiquinone and with either the bound antimycin A(1) or NQNO were determined and refined. A ubiquinone with its first two isoprenoid repeats and an antimycin A(1) were identified in the Q(i) pocket of the substrate and inhibitor bound structures, respectively; the NQNO, on the other hand, was identified in both Q(i) and Q(o) pockets in the inhibitor complex. The two inhibitors occupied different portions of the Q(i) pocket and competed with substrate for binding. In the Q(o) pocket, the NQNO behaves similarly to stigmatellin, inducing an iron-sulfur protein conformational arrest. Extensive binding interactions and conformational adjustments of residues lining the Q(i) pocket provide a structural basis for the high affinity binding of antimycin A and for phenotypes of inhibitor resistance. A two-water-mediated ubiquinone protonation mechanism is proposed involving three Q(i) site residues His(201), Lys(227), and Asp(228).

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Section: Resultsmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Structural Basis for the Quinone Reduction in thebc₁Complex: A Comparative Analysis of Crystal Structures of Mitochondrial Cytochromebc₁with Bound Substrate and Inhibitors at the Q_iSite^,

et al. 2003

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“…It must also be noted that the native AOX activity is important for maintaining redox (and metabolite) homeostasis in plants, and inhibition of this enzyme may be deleterious under osmotic and light stress conditions [83,84]. Nevertheless, the intriguing possibility exists of the development of dual fungal cyt bc 1 /AOX inhibitors, as compounds such as the quinoline aurachins, produced by the myxobacterium Stigmatella aurantiaca , are inhibitors of both enzymes [85–88]. We note also the potential for complex I/cyt bc 1 inhibition for fungicidal activity as Δp would be expected to be severely diminished under such circumstances, regardless of the activity of AOX.…”

Section: Alternative Qoi/qii Resistance Mechanisms In Fungal Phytopatmentioning

confidence: 96%

The cytochrome bc₁ complex as an antipathogenic target

2020

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The cytochrome bc1 complex is a key component of the mitochondrial respiratory chains of many eukaryotic microorganisms that are pathogenic for plants or humans, such as fungi responsible for crop diseases and Plasmodium falciparum, which causes human malaria. Cytochrome bc1 is an enzyme that contains two (ubi)quinone/quinol‐binding sites, which can be exploited for the development of fungicidal and chemotherapeutic agents. Here, we review recent progress in determination of the structure and mechanism of action of cytochrome bc1, and the associated development of antimicrobial agents (and associated resistance mechanisms) targeting its activity.

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“…Genetic studies conducted in different organisms using specific Q0 site (myxothiazol, stigmatellin, and mucidin) (Daldal et al" 1989;Howell & Gilbert, 1988;di Rago et al, 1990) and Qj site (antimycin A, diuron and funiculosin) (di Rago & Colson 1988;Howell & Gilbert, 1988;Park & Daldal, 1992; Uhrig et al, 1994;Coppe et al, 1994) InhR mutants highlighted two specific portions of cyt b (QJ and QJI) as contributing to the Q0 site of the bc\ complex (Figure 1). The QJ region is located between the transmembrane helices C and D and encompasses the transversal helix cd.…”

mentioning

confidence: 99%

Tyrosine 147 of cytochrome b is required for efficient electron transfer at the ubihydroquinone oxidase site (Qo) of the cytochrome bc1 complex

Sarıbaş¹,

Ding²,

Dutton³

et al. 1995

Biochemistry

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In Rhodobacter capsulatus, tyrosine (Y) 147 is a highly conserved residue of the cyt b subunit of the bc1 complex. It is located in the vicinity of residues altered in spontaneous inhibitor resistant mutants that affect the ubihydroquinone oxidase (Qo) site of this enzyme. In this work, Y147 was substituted with phenylalanine (F), valine (V), serine (S), and alanine (A) using site-directed mutagenesis in an effort to investigate its specific role in the Qo site. Of the four mutants obtained, Y147S and Y147A exhibited very low ubihydroquinone:cyt c reductase activities and were unable to support photosynthetic growth (Ps) while Y147F and Y147V were Ps+. In all mutants, no changes in the redox midpoint potentials (Em7) of the cyt bH and cyt bL, the occupancy of the Qo site by Q/QH2, and the flash-induced reverse electron transfer kinetics from Qi to cyt bH were observed. On the other hand, rates of electron transfer from Qo to cyt bH were mildly reduced (2-3-fold) in Y147F and V but dramatically decreased (about 20-fold) in Y147A and S, localizing the defect to the Qo site. Thus, Y147A and S are members of a novel class of Qo site mutants that affect the Qo site catalysis without perturbing the accessibility or binding of the substrate. Additional insight to the role of Y147 on ubihydroquinone oxidation was gained by analyzing the Ps+ revertants of these mutants. Two pseudorevertants contained a second mutation [isoleucine (I) or valine (V)] at the highly conserved M154 position, six residues away from Y147.(ABSTRACT TRUNCATED AT 250 WORDS)

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Molecular characterization of two spontaneous antimycin A resistant mutants of Rhodospirillum rubrum

Cited by 7 publications

References 29 publications

Structural Basis for the Quinone Reduction in thebc₁Complex: A Comparative Analysis of Crystal Structures of Mitochondrial Cytochromebc₁with Bound Substrate and Inhibitors at the Q_iSite^,

Structural Basis for the Quinone Reduction in thebc₁Complex: A Comparative Analysis of Crystal Structures of Mitochondrial Cytochromebc₁with Bound Substrate and Inhibitors at the Q_iSite^,

The cytochrome bc₁ complex as an antipathogenic target

Tyrosine 147 of cytochrome b is required for efficient electron transfer at the ubihydroquinone oxidase site (Qo) of the cytochrome bc1 complex

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Molecular characterization of two spontaneous antimycin A resistant mutants of Rhodospirillum rubrum

Cited by 7 publications

References 29 publications

Structural Basis for the Quinone Reduction in thebc1Complex: A Comparative Analysis of Crystal Structures of Mitochondrial Cytochromebc1with Bound Substrate and Inhibitors at the QiSite,

Structural Basis for the Quinone Reduction in thebc1Complex: A Comparative Analysis of Crystal Structures of Mitochondrial Cytochromebc1with Bound Substrate and Inhibitors at the QiSite,

The cytochrome bc1 complex as an antipathogenic target

Tyrosine 147 of cytochrome b is required for efficient electron transfer at the ubihydroquinone oxidase site (Qo) of the cytochrome bc1 complex

Contact Info

Product

Resources

About

Structural Basis for the Quinone Reduction in thebc₁Complex: A Comparative Analysis of Crystal Structures of Mitochondrial Cytochromebc₁with Bound Substrate and Inhibitors at the Q_iSite^,

Structural Basis for the Quinone Reduction in thebc₁Complex: A Comparative Analysis of Crystal Structures of Mitochondrial Cytochromebc₁with Bound Substrate and Inhibitors at the Q_iSite^,

The cytochrome bc₁ complex as an antipathogenic target