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Planta

Title:		Import of polyphenol oxidase by chloroplasts is enhanced by methyl jasmonate
Author(s):		Koussevitzky S; Ne'eman E; Harel E;
Address:		"Department of Plant Sciences, The Hebrew University, 91904, Jerusalem, Israel. koussevitzky@pop.salk.edu"
Journal Title:		Planta
Year:		2004
Volume:		20040313
Issue:		3
Page Number:		412 - 419
DOI:		10.1007/s00425-004-1240-7
ISSN/ISBN:		0032-0935 (Print) 0032-0935 (Linking)
Abstract:		"Polyphenol oxidase (PPO; EC 1.10.3.2 or EC 1.14.18.1) takes part in the response of tomato plants (Lycopersicon esculentum Mill.) to wounding and herbivore attack, mediated by the octadecanoid wound-signaling pathway. Wounding and methyl jasmonate (MeJA) induce expression of ppo genes and markedly increase the level of the enzyme. We report that pretreatment with MeJA also markedly increased the ability of isolated tomato chloroplasts to import and process PPO precursors (pPPO). Pea (Pisum sativum L.) chloroplasts showed no such response. Wounding or ethylene alone was ineffective but ethylene was synergistic with MeJA. Treatment with MeJA conferred a strong binding of pPPO, or its processing intermediate, to thylakoids and subsequent translocation into the lumen and processing to the mature protein. The effect on PPO import and translocation was evident after 8-16 h exposure to MeJA. Membrane-bound pPPO was cross-linked to a proteinaceous component of the thylakoid translocation apparatus, apparently induced by MeJA. The import and processing of other nuclear-encoded thylakoid proteins were not affected by MeJA in tomato. A 90-kDa protein that co-fractionated with thylakoids was induced along with the increase in competence for PPO import, and was identified as the proteinase-inhibitor multicystatin. It is concluded that the 90-kDa protein observed is part of the MeJA-induced defense response of tomato, not a component of the thylakoid translocation apparatus"
Keywords:		"Acetates/*pharmacology Amino Acid Sequence Biological Transport, Active/drug effects Catechol Oxidase/genetics/*metabolism Chloroplasts/*drug effects/*metabolism Cyclopentanes/*pharmacology Cystatins/genetics/metabolism Enzyme Precursors/metabolism Ethyle;"
Notes:		"MedlineKoussevitzky, Shai Ne'eman, Emma Harel, Eitan eng Research Support, Non-U.S. Gov't Germany 2004/03/17 Planta. 2004 Jul; 219(3):412-9. doi: 10.1007/s00425-004-1240-7. Epub 2004 Mar 13"