Journal Article

E3 Ubiquitin Ligase Activity of Arabidopsis PLANT U-BOX17 and Its Functional Tobacco Homolog ACRE276 Are Required for Cell Death and Defense

Yang, Cheng-Wei, O'Donnell, Elizabeth, Ewan, Richard A, Sadanandom, Ari, Shenton, Matt, González-Lamothe, Rocío, Yoshioka, Hirofumi, Ye, Heng, Jones, Jonathan D.G, Rowland, Owen

2006

Overview

Previous analysis of transcriptional changes after elicitation of Cf-9 transgenic tobacco (Nicotiana tabacum) by Avr9 peptide revealed a rapidly upregulated gene, ACRE276. We show that ACRE276 is transiently induced in wounded leaves within 15 min, but upon Avr9 elicitor treatment, this upregulation is enhanced and maintained until cell death onset in Cf-9 tobacco. ACRE276 RNA interference (RNAi) silencing in tobacco results in loss of hypersensitive response (HR) specified by Cf resistance genes. ACRE276 RNAi plants are also compromised for HR mediated by the tobacco mosaic virus defense elicitor p50. Silencing tomato (Lycopersicon esculentum) ACRE276 leads to breakdown of Cf-9-specified resistance against Cladosporium fulvum leaf mold. We confirmed that tobacco ACRE276 is an E3 ubiquitin ligase requiring an intact U-box domain. Bioinformatic analyses revealed Arabidopsis thaliana PLANT U-BOX17 (PUB17) and Brassica napus ARC1 as the closest homologs of tobacco ACRE276. Transiently expressing PUB17 in Cf-9 tobacco silenced for ACRE276 restores HR, while mutant PUB17 lacking E3 ligase activity fails to do so, demonstrating that PUB17 ligase activity is crucial for defense signaling. Arabidopsis PUB17 knockout plants are compromised in RPM1- and RPS4-mediated resistance against Pseudomonas syringae pv tomato containing avirulence genes AvrB and AvrRPS4, respectively. We identify a conserved class of U-box ARMADILLO repeat E3 ligases that are positive regulators of cell death and defense across the Solanaceae and Brassicaceae.

• Publisher: American Society of Plant Biologists
• Subject: ACRE276 gene / Agrobacterium / Amino Acid Sequence / Arabidopsis / Arabidopsis - enzymology / Arabidopsis - genetics / Arabidopsis Proteins / Arabidopsis Proteins - genetics / Arabidopsis Proteins - metabolism / Arabidopsis thaliana / bacterial diseases of plants / Brassica napus / Brassicaceae / Brassicaceae - enzymology / Cell Death / Cladosporium fulvum / Complementary DNA / cytology / Disease resistance / E3 ubiquitin ligase / enzyme activity / Enzymes / enzymology / Fulvia fulva / fungal diseases of plants / gene expression / gene induction / genetics / hypersensitive response / Immunity, Innate / immunology / Leaves / ligases / Lycopersicon esculentum / mechanical damage / messenger RNA / metabolism / Molecular Sequence Data / Mortality / Nicotiana - cytology / Nicotiana - enzymology / Nicotiana - immunology / Nicotiana tabacum / Passalora fulva / Plant cells / Plant Diseases / Plant Proteins / Plant Proteins - genetics / Plant Proteins - metabolism / Plants / Pseudomonas syringae / Pseudomonas syringae pv. tomato / PUB17 gene / resistance mechanisms / Reverse transcriptase polymerase chain reaction / Sequence Alignment / Sequence Homology, Amino Acid / Solanaceae / Solanaceae - enzymology / Solanum lycopersicum / Solanum lycopersicum - enzymology / Solanum lycopersicum - genetics / Tobacco / Tobacco mosaic virus / Tomatoes / Transcription, Genetic / Ubiquitin-Protein Ligases / Ubiquitin-Protein Ligases - genetics / Ubiquitin-Protein Ligases - metabolism / Ubiquitins