Oxidative α-Ketoglutarate Dehydrogenase Inhibition via Subtle Elevations in Monoamine Oxidase B Levels Results in Loss of Spare Respiratory Capacity

Kumar, M. Jyothi; Nicholls, David G.; Andersen, Julie K.

doi:10.1074/jbc.m306378200

Cited by 114 publications

(78 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Moreover, studies of the response of intact isolated nerve terminals to oxidative stress demonstrated that, although the aconitase enzyme was the most vulnerable to oxidative damage, it is the inhibition of the 2-oxoglutarate dehydrogenase complex that limits the amount of NADH available for the respiratory chain (Tretter and Adam-Vizi, 2000). Similar conclusions were also drawn following treatment of brain cells with monoamine oxidase (Kumar et al, 2003). These results suggest that in these systems the 2-oxoglutarate dehydrogenase complex exhibits a large proportion of the control resident in the TCA cycle.…”

supporting

confidence: 73%

Inhibition of 2-Oxoglutarate Dehydrogenase in Potato Tuber Suggests the Enzyme Is Limiting for Respiration and Confirms Its Importance in Nitrogen Assimilation

et al. 2008

View full text Add to dashboard Cite

The 2-oxoglutarate dehydrogenase complex constitutes a mitochondrially localized tricarboxylic acid cycle multienzyme system responsible for the conversion of 2-oxoglutarate to succinyl-coenzyme A concomitant with NAD + reduction. Although regulatory mechanisms of plant enzyme complexes have been characterized in vitro, little is known concerning their role in plant metabolism in situ. This issue has recently been addressed at the cellular level in nonplant systems via the use of specific phosphonate inhibitors of the enzyme. Here, we describe the application of these inhibitors for the functional analysis of the potato (Solanum tuberosum) tuber 2-oxoglutarate dehydrogenase complex. In vitro experiments revealed that succinyl phosphonate (SP) and a carboxy ethyl ester of SP are slow-binding inhibitors of the 2-oxoglutarate dehydrogenase complex, displaying greater inhibitory effects than a diethyl ester of SP, a phosphono ethyl ester of SP, or a triethyl ester of SP. Incubation of potato tuber slices with the inhibitors revealed that they were adequately taken up by the tissue and produced the anticipated effects on the in situ enzyme activity. In order to assess the metabolic consequences of the 2-oxoglutarate dehydrogenase complex inhibition, we evaluated the levels of a broad range of primary metabolites using an established gas chromatography-mass spectrometry method. We additionally analyzed the rate of respiration in both tuber discs and isolated mitochondria. Finally, we evaluated the metabolic fate of radiolabeled acetate, 2-oxoglutarate or glucose, and 13 C-labeled pyruvate and glutamate following incubation of tuber discs in the presence or absence of either SP or the carboxy ethyl ester of SP. The data obtained are discussed in the context of the roles of the 2-oxoglutarate dehydrogenase complex in respiration and carbon-nitrogen interactions.

show abstract

supporting

confidence: 73%

Inhibition of 2-Oxoglutarate Dehydrogenase in Potato Tuber Suggests the Enzyme Is Limiting for Respiration and Confirms Its Importance in Nitrogen Assimilation

et al. 2008

View full text Add to dashboard Cite

show abstract

“…Genetic studies considered polymorphisms in the DLST (encoding E2k) or DLD (encoding E3) genes to be a risk factor for the manifestation of Parkinson or Alzheimer diseases (43,44). Increased oxidative stress is one plausible link between KGDHc deficiency and neurodegeneration, because KGDHc contains a labile Fe-S center, and is sensitive to a number of oxidants including 4-hydroxy-2-nonenal, H 2 O 2 , NO, peroxynitrite, hypochlorous acid, and mono-N-chloramine (34,(45)(46)(47).…”

Section: Reduction Of Flux Through Tca Cycle Via Inhibition Of Kgdhc Bymentioning

confidence: 99%

Bioenergetics in Glutaryl-Coenzyme A Dehydrogenase Deficiency

Sauer

Okun

Schwab

et al. 2005

Journal of Biological Chemistry

111

View full text Add to dashboard Cite

Inherited deficiency of glutaryl-CoA dehydrogenase results in an accumulation of glutaryl-CoA, glutaric, and 3-hydroxyglutaric acids. If untreated, most patients suffer an acute encephalopathic crisis and, subsequently, acute striatal damage being precipitated by febrile infectious diseases during a vulnerable period of brain development (age 3 and 36 months). It has been suggested before that some of these organic acids may induce excitotoxic cell damage, however, the relevance of bioenergetic impairment is not yet understood. The major aim of our study was to investigate respiratory chain, tricarboxylic acid cycle, and fatty acid oxidation in this disease using purified single enzymes and tissue homogenates from Gcdh-deficient and wild-type mice. In purified enzymes, glutaryl-CoA but not glutaric or 3-hydroxyglutaric induced an uncompetitive inhibition of ␣-ketoglutarate dehydrogenase complex activity. Notably, reduced activity of ␣-ketoglutarate dehydrogenase activity has recently been demonstrated in other neurodegenerative diseases, such as Alzheimer, Parkinson, and Huntington diseases. In contrast to ␣-ketoglutarate dehydrogenase complex, no direct inhibition of glutaryl-CoA, glutaric acid, and 3-hydroxyglutaric acid was found in other enzymes tested. In Gcdh-deficient mice, respiratory chain and tricarboxylic acid activities remained widely unaffected, virtually excluding regulatory changes in these enzymes. However, hepatic activity of very long-chain acyl-CoA dehydrogenase was decreased and concentrations of long-chain acylcarnitines increased in the bile of these mice, which suggested disturbed oxidation of long-chain fatty acids. In conclusion, our results demonstrate that bioenergetic impairment may play an important role in the pathomechanisms underlying neurodegenerative changes in glutaryl-CoA dehydrogenase deficiency.

show abstract

“…These oxidation processes are important in maintaining physiological levels of dopamine and free dietary amines in our body and proper functioning of the central nervous system. Age related increases in the expression levels of MAOB in neural tissues [2,3] are implicated in several neurological disorders like, Parkinson's and Alzheimer's diseases and selective MAOB inhibitors are clinically proven drug adjuvants for treating these disorders [4,5].…”

Section: Introductionmentioning

confidence: 99%

Characterization of detergent purified recombinant rat liver monoamine oxidase B expressed in Pichia pastoris

Upadhyay

Edmondson

2008

Protein Expression and Purification

View full text Add to dashboard Cite

The high level expression and purification of rat monoamine oxidase B (rMAOB) in the methylotrophic yeast Pichia pastoris is reported. Nearly 100 mg of purified rMAOB is obtained from 130 grams (wet weight) of cells (0.5 liter of culture). The MALDI-TOF mass spectrum of the purified protein shows a single species with a molecular mass of 59.228 ± 0.064 kDa, which agrees with the calculated molecular weight of 59.172 kDa for the rMAOB protein sequence assuming one mole of covalent FAD per mole of the enzyme. Consistent with the MALDI-MS data, purified rMAOB shows a single band near 60 kDa in Coomassie stained SDS/PAGE gel as well as on Western blot analyses performed using antiseras raised against human MAOA and BSA conjugated FAD. A partial amino acid sequence of the purified protein is confirmed to be that of the wild type rMAOB by in-gel trypsin digestion and MALDI-TOF-MS analyses of the liberated peptide fragments. Steady state kinetic data show that purified rMAOB exhibits a K m (amine) of 176 ± 15 µM and a k cat of 497 ± 83 min −1 for benzylamine oxidation, and a K m (O 2 ) of 170 ± 10 µM. Kinetic parameters obtained for purified rMAOB are compared with those reported earlier for recombinant human liver MAOB expressed in Pichia pastoris. KeywordsMonoamine Oxidase B; Rat Liver MAOB; Pichia pastoris Monoamine oxidase B (MAOB) 1 is an outer mitochondrial membrane bound flavoenzyme responsible for oxidative deamination and subsequent degradation of dopamine and dietary amines in our body [1]. These oxidation processes are important in maintaining physiological levels of dopamine and free dietary amines in our body and proper functioning of the central nervous system. Age related increases in the expression levels of MAOB in neural tissues [2,3] are implicated in several neurological disorders like, Parkinson's and Alzheimer's diseases and selective MAOB inhibitors are clinically proven drug adjuvants for treating these disorders [4,5].Owing to their therapeutic applications, developments of MAOB inhibitors with greater clinical potency have gained momentum in recent years. Rat, being one of the most common 1 This work was supported by National Institute of Health Grant GM-29433 (DEE).2To whom correspondence should be addressed: 1510 Clifton Road NE, Atlanta, GA 30322. E-mail: deedmon@emory.edu, Phone: 404-727-5972, Fax: 404-727-2738. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. animal models, is generally used for the screening of potential drug candidates. However, recent quantitative studies have shown differences in inhibitor specificities and properties b...

show abstract

Oxidative α-Ketoglutarate Dehydrogenase Inhibition via Subtle Elevations in Monoamine Oxidase B Levels Results in Loss of Spare Respiratory Capacity

Cited by 114 publications

References 63 publications

Inhibition of 2-Oxoglutarate Dehydrogenase in Potato Tuber Suggests the Enzyme Is Limiting for Respiration and Confirms Its Importance in Nitrogen Assimilation

Inhibition of 2-Oxoglutarate Dehydrogenase in Potato Tuber Suggests the Enzyme Is Limiting for Respiration and Confirms Its Importance in Nitrogen Assimilation

Bioenergetics in Glutaryl-Coenzyme A Dehydrogenase Deficiency

Characterization of detergent purified recombinant rat liver monoamine oxidase B expressed in Pichia pastoris

Contact Info

Product

Resources

About