The RING-Type E3 Ligase XBAT35.2 is involved in cell death induction and pathogen response

Hongxia Liu, Sridhar Ravichandran, Ooi Kock Teh, Sarah McVey, Carly Lilley, Howard J. Teresinski, Carmen Gonzalez-Ferrer, Robert T. Mullen, Daniel Hofius, Balakrishnan Prithiviraj, Sophia L. Stonea

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)

Abstract

XBAT35 belongs to a subfamily of Arabidopsis (Arabidopsis thaliana) RING-type E3s that are similar in domain architecture to the rice (Oryza sativa) XA21 Binding Protein3, a defense protein. The XBAT35 transcript undergoes alternative splicing to produce two protein isoforms, XBAT35.1 and XBAT35.2. Here, we demonstrate that XBAT35.2 localizes predominantly to the Golgi and is involved in cell death induction and pathogen response. XBAT35.2, but not XBAT35.1, was found to trigger cell death when overexpressed in tobacco (Nicotiana benthamiana) leaves and does so in a manner that requires its RING domain. Loss of XBAT35 gene function disrupts the plant’s ability to defend against pathogen attack, whereas overexpression of XBAT35.2 enhances resistance to pathogens. XBAT35.2 was found to be unstable and promotes its own degradation, suggesting self-regulation. Inoculation with virulent and avirulent strains of the bacterial pathogen Pseudomonas syringae pv tomato DC3000 results in a drastic reduction in the levels of ubiquitinated XBAT35.2 and an increase in the abundance of the E3. This implies that pathogen infection prohibits XBAT35.2 self-regulation and stabilizes the E3. In agreement with a role in defending against pathogens, XBAT35.2 interacts with defense-related Accelerated Cell Death11 (ACD11) in planta and promotes the proteasome-dependent turnover of ACD11 in cell-free degradation assays. In accordance with regulation by a stabilized XBAT35.2, the levels of ubiquitinated ACD11 increased considerably, and the abundance of ACD11 was reduced following pathogen infection. In addition, treatment of transgenic seedlings with a proteasome inhibitor results in the accumulation of ACD11, confirming proteasome-dependent degradation. Collectively, these results highlight a novel role for XBAT35.2 in cell death induction and defense against pathogens.

Original languageEnglish
Pages (from-to)1469-1483
Number of pages15
JournalPlant Physiology
Volume175
Issue number3
DOIs
Publication statusPublished - Nov 2017
Externally publishedYes

Bibliographical note

Funding Information:
1 This research was supported by grants from the Natural Science and Engineering Research Council of Canada (NSERC) to S.L.S., R.T. M., and B.P. H.J.T. was supported by an Ontario Graduate Scholarship, and S.M. was supported by a NSERC Canada Graduate Scholarships-Master’s (CGS M) scholarship.

Publisher Copyright:
© 2017 American Society of Plant Biologists. All rights reserved.

ASJC Scopus Subject Areas

  • Physiology
  • Genetics
  • Plant Science

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