HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 282, Issue 34, 24980-24989, August 24, 2007

This Article Full Text Full Text (PDF) All Versions of this Article: 282/34/24980    most recent M701028200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lucas, K. A. Articles by Hawes, J. W. Search for Related Content PubMed PubMed Citation Articles by Lucas, K. A. Articles by Hawes, J. W. Social Bookmarking                      What's this?

Peroxisomal Metabolism of Propionic Acid and Isobutyric Acid in Plants^*

From the Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056

The subcellular sites of branched-chain amino acid metabolism in plants have been controversial, particularly with respect to valine catabolism. Potential enzymes for some steps in the valine catabolic pathway are clearly present in both mitochondria and peroxisomes, but the metabolic functions of these isoforms are not clear. The present study examined the possible function of these enzymes in metabolism of isobutyryl-CoA and propionyl-CoA, intermediates in the metabolism of valine and of odd-chain and branched-chain fatty acids. Using ¹³C NMR, accumulation of -hydroxypropionate from [2-¹³C]propionate was observed in seedlings of Arabidopsis thaliana and a range of other plants, including both monocots and dicots. Examination of coding sequences and subcellular targeting elements indicated that the completed genome of A. thaliana likely codes for all the enzymes necessary to convert valine to propionyl-CoA in mitochondria. However, Arabidopsis mitochondria may lack some of the key enzymes for metabolism of propionyl-CoA. Known peroxisomal enzymes may convert propionyl-CoA to -hydroxypropionate by a modified -oxidation pathway. The chy1–3 mutation, creating a defect in a peroxisomal hydroxyacyl-CoA hydrolase, abolished the accumulation of -hydroxyisobutyrate from exogenous isobutyrate, but not the accumulation of -hydroxypropionate from exogenous propionate. The chy1–3 mutant also displayed a dramatically increased sensitivity to the toxic effects of excess propionate and isobutyrate but not of valine. ¹³C NMR analysis of Arabidopsis seedlings exposed to [U-¹³C]valine did not show an accumulation of -hydroxypropionate. No evidence was observed for a modified -oxidation of valine. ¹³C NMR analysis showed that valine was converted to leucine through the production of -ketoisovalerate and isopropylmalate. These data suggest that peroxisomal enzymes for a modified -oxidation of isobutyryl-CoA and propionyl-CoA could function for metabolism of substrates other than valine.

Received for publication, February 2, 2007 , and in revised form, June 18, 2007.

^* The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed: Dept. of Chemistry and Biochemistry, Miami University, Oxford, OH 45056. Tel.: 513-529-8072; Fax: 513-529-5715; E-mail: hawesjw{at}muohio.edu.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				C.-H. Dong, B. K. Zolman, B. Bartel, B.-h. Lee, B. Stevenson, M. Agarwal, and J.-K. Zhu Disruption of Arabidopsis CHY1 Reveals an Important Role of Metabolic Status in Plant Cold Stress Signaling Mol Plant, January 1, 2009; 2(1): 59 - 72. [Abstract] [Full Text] [PDF]

				T. Ogawa, K. Yoshimura, H. Miyake, K. Ishikawa, D. Ito, N. Tanabe, and S. Shigeoka Molecular Characterization of Organelle-Type Nudix Hydrolases in Arabidopsis Plant Physiology, November 1, 2008; 148(3): 1412 - 1424. [Abstract] [Full Text] [PDF]

				B. K. Zolman, N. Martinez, A. Millius, A. R. Adham, and B. Bartel Identification and Characterization of Arabidopsis Indole-3-Butyric Acid Response Mutants Defective in Novel Peroxisomal Enzymes Genetics, September 1, 2008; 180(1): 237 - 251. [Abstract] [Full Text] [PDF]