title: The mitochondrial connection: Arginine degradation versus arginine conversion to nitric oxide.
abstract: Arg catabolism to cytoplasmic urea and glutamate is initiated by two mitochondrial enzymes, arginase and ornithine aminotransferase. Mutation of either enzyme leads to Arg sensitivity, and at least in the former, an arginine-induced seedling morphology similar to exogenous auxin treatment. We reported that single mutants lacking either of two arginase isozymes exhibited more NO accumulation and efflux, and increased responses to auxin (measured by DR5 reporter expression and auxin-induced lateral roots). We discuss evidence for stimulation of NO by arginine, either directly, or via polyamines derived from arginine. We favor the "direct" route because mitochondria are sites of NO 'hot spots,' and the location of arginine-degrading enzymes and the NO-associated protein1. The polyamine "branch" invokes more than one cell compartment, at least two intermediates (polyamines and H(2)O(2)) between Arg and NO, and is not consistent with enhanced lateral root formation in arginine decarboxylase mutants. Genetic tools are at our disposal to test the two possible routes of arginine-derived NO.
authors.affiliation: Biochemistry Department; University of Missouri; Columbia, Missouri USA.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Tovar-Mendez
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Todd
authors.forename: Joe C
authors.initials: JC
authors.lastname: Polacco
references.citation: Plant Cell. 1997 Oct;9(10):1781-90
references.pmid: 9368415
references.citation: BMC Plant Biol. 2008 Apr 17;8:40
references.pmid: 18419821
references.citation: J Exp Bot. 2008;59(1):25-35
references.pmid: 17975211
references.citation: J Biol Chem. 2003 Feb 21;278(8):6490-4
references.pmid: 12482758
references.citation: Proc Natl Acad Sci U S A. 2004 Nov 2;101(44):15811-6
references.pmid: 15498873
references.citation: Annu Rev Plant Physiol Plant Mol Biol. 1997 Jun;48:109-136
references.pmid: 15012259
references.citation: Plant Cell. 2005 Dec;17(12):3436-50
references.pmid: 16272429
references.citation: Plant J. 2001 Sep;27(6):551-60
references.pmid: 11576438
references.citation: Biochim Biophys Acta. 2006 Sep-Oct;1757(9-10):1277-83
references.pmid: 16730327
references.citation: Plant J. 2003 Mar;33(6):1027-35
references.pmid: 12631327
references.citation: Plant J. 2006 Jan;45(1):113-22
references.pmid: 16367958
references.citation: Trends Plant Sci. 2006 Feb;11(2):80-8
references.pmid: 16406305
references.citation: Plant Cell Physiol. 2006 Mar;47(3):346-54
references.pmid: 16415068
references.citation: Plant J. 1998 Jan;13(2):231-9
references.pmid: 9680979
references.citation: New Phytol. 2007;174(2):332-341
references.pmid: 17388896
references.citation: Plant Cell Physiol. 2008 Sep;49(9):1272-82
references.pmid: 18703589
references.citation: Lipids. 2004 Nov;39(11):1045-53
references.pmid: 15726818
references.citation: Nucleic Acids Res. 2007 Jan;35(Database issue):D213-8
references.pmid: 17071959
references.citation: Planta. 2008 Aug;228(3):367-81
references.pmid: 18594857
references.citation: Plant Physiol. 2004 Sep;136(1):2875-86
references.pmid: 15347797
references.citation: Science. 2003 Oct 3;302(5642):100-3
references.pmid: 14526079
references.citation: Planta. 2006 Jul;224(2):246-54
references.pmid: 16397797
references.citation: J Exp Bot. 2006;57(3):471-8
references.pmid: 16356941
references.citation: Plant Cell. 2006 Oct;18(10):2749-66
references.pmid: 16998070
references.citation: Plant Physiol. 2008 Aug;147(4):1936-46
references.pmid: 18567826
references.citation: Plant Physiol. 1999 Jan;119(1):297-304
references.pmid: 9880372