« Previous AbstractControllable synthesis of Y2O3 microstructures for application in cataluminescence gas sensing    Next AbstractAlternative oxidase in resistance to biotic stresses: Nicotiana attenuata AOX contributes to resistance to a pathogen and a piercing-sucking insect but not Manduca sexta larvae »

J Biol Chem

Title:		"Functional analysis of the type 3 effector nodulation outer protein L (NopL) from Rhizobium sp. NGR234: symbiotic effects, phosphorylation, and interference with mitogen-activated protein kinase signaling"
Author(s):		Zhang L; Chen XJ; Lu HB; Xie ZP; Staehelin C;
Address:		"State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China"
Journal Title:		J Biol Chem
Year:		2011
Volume:		20110720
Issue:		37
Page Number:		32178 - 32187
DOI:		10.1074/jbc.M111.265942
ISSN/ISBN:		1083-351X (Electronic) 0021-9258 (Print) 0021-9258 (Linking)
Abstract:		"Pathogenic bacteria use type 3 secretion systems to deliver virulence factors (type 3 effector proteins) directly into eukaryotic host cells. Similarly, type 3 effectors of certain nitrogen-fixing rhizobial strains affect nodule formation in the symbiosis with host legumes. Nodulation outer protein L (NopL) of Rhizobium sp. strain NGR234 is a Rhizobium-specific type 3 effector. Nodulation tests and microscopic analysis showed that distinct necrotic areas were rapidly formed in ineffective nodules of Phaseolus vulgaris (cv. Tendergreen) induced by strain NGROmeganopL (NGR234 mutated in nopL), indicating that NopL antagonized nodule senescence. Further experiments revealed that NopL interfered with mitogen-activated protein kinase (MAPK) signaling in yeast and plant cells (Nicotiana tabacum). Expression of nopL in yeast disrupted the mating pheromone (alpha-factor) response pathway, whereas nopL expression in N. tabacum suppressed cell death induced either by overexpression of the MAPK gene SIPK (salicylic acid-induced protein kinase) or by SIPK(DD) (mutation in the TXY motif resulting in constitutive MAPK activity). These data indicate that NopL impaired function of MAPK proteins or MAPK substrates. Furthermore, we demonstrate that NopL was multiply phosphorylated either in yeast or N. tabacum cells that expressed nopL. Four phosphorylated serines were confirmed by mass spectrometry. All four phosphorylation sites exhibit a Ser-Pro pattern, a typical motif in MAPK substrates. Taken together, data suggest that NopL mimics a MAPK substrate and that NopL suppresses premature nodule senescence by impairing MAPK signaling in host cells"
Keywords:		Amino Acid Motifs Bacterial Proteins/genetics/*metabolism MAP Kinase Signaling System Mitogen-Activated Protein Kinase Kinases/genetics/metabolism Phaseolus/genetics/*metabolism/microbiology Phosphorylation/*physiology Plant Proteins/genetics/metabolism R;
Notes:		"MedlineZhang, Ling Chen, Xue-Jiao Lu, Huang-Bin Xie, Zhi-Ping Staehelin, Christian eng Research Support, Non-U.S. Gov't 2011/07/22 J Biol Chem. 2011 Sep 16; 286(37):32178-87. doi: 10.1074/jbc.M111.265942. Epub 2011 Jul 20"