Isolation and characterization of a cDNA clone encoding an alternative oxidase protein of Sauromatum guttatum (Schott).

Rhoads, David M.; McIntosh, Lee

doi:10.1073/pnas.88.6.2122

Cited by 155 publications

(108 citation statements)

References 42 publications

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“…This may represent accumulation of a mitochondrial precursor form of the 35-kD protein. In the thermogenic plant S. guttatum, there are at least 3 AO proteins of similar molecular mass that most likely represent posttranslational modifications of a single nuclear gene product (10,19). As CP capacity recovered (Fig.…”

Section: Discussionmentioning

confidence: 99%

Coordinate Regulation of Cytochrome and Alternative Pathway Respiration in Tobacco

Vanlerberghe

McIntosh²

1992

Plant Physiol.

103

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In suspension cells of NT1 tobacco (Nicotiana tabacum L. cv bright yellow), inhibition of the cytochrome pathway of respiration with antimycin A induced a large increase in the capacity of the alternative pathway over a period of approximately 12 h, as confirmed in both whole cells and isolated mitochondria. The increase in alternative pathway capacity required de novo RNA Mitochondrial electron transport in plants may proceed through either the CP2 or the AP (6,12,14). Transfer of electrons from NADH through the CP is coupled at three sites to the translocation of protons from the matrix to the intermembrane space. Reentry of protons to the matrix through complex V (mitochondrial ATP synthetase) results in the production of ATP. In this case, carbon oxidation in respiration is coupled to the production of ATP, and in many instances respiration rate is tightly regulated by the availability of ADP (i.e. adenylate control) (8, 12). Transfer of electrons through the AP bypasses two of the three sites of proton translocation. Under these conditions, carbon oxidation is not as tightly coupled to the production of ATP, and it is expected that respiration rate would not be as strictly regulated by the availability of ADP (8,12 It seems imperative that plants be able to regulate in a coordinate fashion the partitioning of electrons between the CP and the AP to meet changing metabolic requirements. Two important factors to be regulated will be, first, the capacity of each pathway to transfer electrons, and second, the degree to which that capacity is used (i.e. the degree of engagement of the pathway). The degree of engagement of the AP is dependent upon the redox poise of the ubiquinone pool (9) and, to some extent, upon the substrates being oxidized by the mitochondria (7).Although many studies indicate that plants are capable of altering the capacity of the AP (6, 14), little is known about the mechanisms by which this occurs. Some studies show that inhibition of the CP with respiratory inhibitors increases AP respiration. For example, treatment of rice roots with low concentrations of KCN or NaN3 for 6 h resulted in increased CN-resistant respiration, although it was not shown whether this CN-resistant respiration was sensitive to SHAM (11). In pea roots, a CN-resistant and SHAM-sensitive component of respiration was induced after several hours of KCN treatment (28). From the above reports, it is not clear whether the KCN treatment increased the capacity or simply the engagement of the AP. Also, interpretation of the data is hampered because KCN is known to inhibit many enzymes of metabolism (29). Nevertheless, inhibition of the CP by a specific respiratory inhibitor may be a useful tool to study mechanisms of induction of AP capacity in plants.AA is a specific inhibitor that blocks electron transfer between Cyt b and cl in the CP (20,23). In Euglena gracilis, addition of AA induced CN-resistant respiration within 5 h (2-4). A similar induction was seen in the yeast Hansenula anomala (17) and led to the ide...

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Section: Discussionmentioning

confidence: 99%

Coordinate Regulation of Cytochrome and Alternative Pathway Respiration in Tobacco

Vanlerberghe

McIntosh²

1992

Plant Physiol.

103

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“…Plasmids-pSLA-250 was constructed by ligating a 250-bp ApaINcoI fragment from pAOSG81 (17) to ApaI-NcoI-digested pSL1180 (Amersham Biosciences, Inc.). pSLM is a modified version of pSL1180 that lacks the 50-bp BamHI-EcoRI region of the multiple cloning site.…”

Section: Methodsmentioning

confidence: 99%

Structure of the Plant Alternative Oxidase

Albury

Affourtit

Crichton

et al. 2002

Journal of Biological Chemistry

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All higher plants and many fungi contain an alternative oxidase (AOX), which branches from the cytochrome pathway at the level of the quinone pool. In an attempt, first, to distinguish between two proposed structural models of this di-iron protein, and, second, to examine the roles of two highly conserved tyrosine residues, we have expressed an array of site-specific mutants in Schizosaccharomyces pombe. Mitochondrial respiratory analysis reveals that S. pombe cells expressing AOX proteins in which Glu-217 or Glu-270 were mutated, no longer exhibit antimycin-resistant oxygen uptake, indicating that these residues are essential for AOX activity. Although such data corroborate a model that describes the AOX as an interfacial membrane protein, they are not in full agreement with the most recently proposed ligation sphere of its di-iron center. We furthermore show that upon mutation of Tyr-253 and Tyr-275 to phenylalanines, AOX activity is fully maintained or abolished, respectively. These data are discussed in reference to the importance of both residues in the catalytic cycle of the AOX. The alternative oxidase (AOX)1 is a ubiquinol:oxygen oxidoreductase that catalyzes the four electron reduction of oxygen to water (for recent reviews, see Refs. 1-4). This terminal oxidase branches from the cytochrome pathway at the level of the ubiquinone pool and is non-protonmotive. The AOX is resistant to inhibitors of the cytochrome pathway such as cyanide and antimycin A but inhibited by a number of compounds including hydroxamic acids (e.g. salicylhydroxamic acid) and n-alkyl-gallates.Two structural models of the AOX currently exist. The first model proposed by Siedow et al. (5,6) was based on relatively few AOX sequences and classified the AOX as a member of the di-iron family of proteins that also includes the R2 subunit of ribonucleotide reductase and the hydroxylase component of methane monooxygenase. Based on hydropathy analysis, the AOX was predicted to contain two transmembrane helices that are connected by a helix located in the intermembrane space (6) (Fig. 1A). Since this model was proposed, further AOX sequences were identified, resulting in the proposal by Andersson and Nordlund (7) of an alternative structural model (Fig. 1B). Although this second model also classifies the AOX as a di-iron protein, it differs in the precise ligation sphere of the di-iron center (7). For instance, one of the C-terminal Glu-X-X-His motifs identified by Siedow et al. (5,6), containing Glu-270, appeared not to be fully conserved in the newly identified sequences and consequently seemed unlikely to play a role in ligating iron. Instead, Andersson and Nordlund used a third Glu-X-X-His motif (that contains Glu-217, which is located in the intermembrane space according to the Siedow et al. model) to coordinate the iron atoms. Since such a choice implies that the transmembrane helices can no longer be retained, Andersson and Nordlund (7) proposed that the AOX is an interfacial rather than a transmembrane protein.Recently, the IMMUTANS (...

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“…The signal probably corresponded to the mature AOX2 mRNA, since the size of AOX2 cDNA can be estimated to be approximately 1.8-1.9 kb. Kirimura et al 1999), Candida albicans (Ca;Huh and Kang 1999), Magnaporthe grisea (Mg; Yukioka et al 1998), Neurospora crassa (Nc;Li et al 1996) and Pichia anomala (Pa; formerly known as Hansenula anomala; Sakajo et al 1991) and the higher plants Arabidopsis thaliana (At; Kumar and Soil 1992) and Sauromatum guttatum (Sg; Rhoads and McIntosh 1991). Amino acid residues identical in at least 50% of sequences are shown on a black background.…”

Section: Expression Of Aox1 and Aox2 Genes And Determination Of The Tmentioning

confidence: 99%

Characterization of two genes encoding the mitochondrial alternative oxidase in Chlamydomonas reinhardtii

Dinant¹,

Baurain²,

Coosemans³

et al. 2001

Current Genetics

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Two cDNA clones (AOX1 and AOX2) and the corresponding genes encoding the alternative oxidases (AOXs) from Chlamydomonas reinhardtii were isolated and sequenced. The cDNAs, AOX1 and AOX2, contained open reading frames (ORFs) encoding putative proteins of 360 amino acids and 347 amino acids, respectively. For each of the ORFs, a potential mitochondrial-targeting sequence was found in the 5'-end regions. In comparison to AOX enzymes from plants and fungi, the predicted amino acid sequences of the ORFs showed their highest degree of identity with proteins from Aspergillus niger (38.1% and 37.2%) and Ajellomyces capsulatus (37% and 34.9%). Several residues supposed either to be Fe ligands or to be involved in the ubiquinol-binding site were fully conserved in both C. reinhardtii putative AOX proteins. In contrast, a cysteine residue conserved in the sequences of all higher plants and probably involved in the regulation of the enzyme activity was missing both from the AOX1 and AOX2 amino acid sequences and from protein sequences from various other microorganisms. The transcriptional expression of the AOX1 and AOX2 genes in wild-type cells and in mutant cells deficient in mitochondrial complex III activity was also investigated.

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Isolation and characterization of a cDNA clone encoding an alternative oxidase protein of Sauromatum guttatum (Schott).

Cited by 155 publications

References 42 publications

Coordinate Regulation of Cytochrome and Alternative Pathway Respiration in Tobacco

Coordinate Regulation of Cytochrome and Alternative Pathway Respiration in Tobacco

Structure of the Plant Alternative Oxidase

Characterization of two genes encoding the mitochondrial alternative oxidase in Chlamydomonas reinhardtii

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