Please use this identifier to cite or link to this item: http://hdl.handle.net/2445/103386
Title: RipAY, a plant pathogen effector protein exhibits robust γ-glutamyl cyclotransferase activity when stimulated by eukaryotic thioredoxins
Author: Fujiwara, S.
Kawazoe, T.
Ohnishi, K.
Kitagawa, T.
Popa, C.
Valls i Matheu, Marc
Genin, S.
Nakamura, K.
Kuramitsu, Y.
Tanaka, N.
Tabuchi, M.
Keywords: Saccharomyces cerevisiae
Botànica
Proteïnes
Reacció d'oxidació-reducció
Saccharomyces cerevisiae
Botany
Proteins
Oxidation-reduction reaction
Issue Date: 8-Jan-2016
Publisher: American Society for Biochemistry and Molecular Biology
Abstract: The plant pathogenic bacterium Ralstonia solanacearum injects more than 70 effector proteins (virulence factors) into the host plant cells via the needle-like structure of a type III secretion system. The type III secretion system effector proteins manipulate host regulatory networks to suppress defense responses with diverse molecular activities. Uncovering the molecular function of these effectors is essential for a mechanistic understanding of R. solanacearum pathogenicity. However, few of the effectors from R. solanacearum have been functionally characterized, and their plant targets remain largely unknown. Here, we show that the ChaC domain-containing effector RipAY/RSp1022 from R. solanacearum exhibits γ-glutamyl cyclotransferase (GGCT) activity to degrade the major intracellular redox buffer, glutathione. Heterologous expression of RipAY, but not other ChaC family proteins conserved in various organisms, caused growth inhibition of yeast Saccharomyces cerevisiae, and the intracellular glutathione level was decreased to ∼30% of the normal level following expression of RipAY in yeast. Although active site mutants of GGCT activity were non-toxic, the addition of glutathione did not reverse the toxicity, suggesting that the toxicity might be a consequence of activity against other γ-glutamyl compounds. Intriguingly, RipAY protein purified from a bacterial expression system did not exhibit any GGCT activity, whereas it exhibited robust GGCT activity upon its interaction with eukaryotic thioredoxins, which are important for intracellular redox homeostasis during bacterial infection in plants. Our results suggest that RipAY has evolved to sense the host intracellular redox environment, which triggers its enzymatic activity to create a favorable environment for R. solanacearum infection.
Note: Reproducció del document publicat a: https://doi.org/10.1074/jbc.M115.678953
It is part of: Journal of Biological Chemistry, 2016, vol. 291, num. 13, p. 6813-6830
Related resource: https://doi.org/10.1074/jbc.M115.678953
URI: http://hdl.handle.net/2445/103386
ISSN: 0021-9258
Appears in Collections:Articles publicats en revistes (Genètica, Microbiologia i Estadística)

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