Publication Information
Ma et al., 2021
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Abstract
Plant Physiol. 2021 Apr 23;185(4):1943-1965. doi: 10.1093/plphys/kiab011.
Ubiquitylome analysis reveals a central role for the ubiquitin-proteasome system
in plant innate immunity.
Ma X(1), Zhang C(2), Kim DY(3)(4), Huang Y(1), Chatt E(5), He P(1), Vierstra
RD(3)(5), Shan L(1)(2).
Author information:
(1)Department of Biochemistry and Biophysics, Texas A&M University, College
Station, Texas 77843.
(2)Department of Plant Pathology and Microbiology, Texas A&M University, College
Station, Texas 77843.
(3)Department of Genetics, University of Wisconsin-Madison, 425-G Henry Mall,
Madison, Wisconsin 53706.
(4)Advanced Bio Convergence Center, Pohang Technopark, Gyeong-Buk 37668, South
Korea.
(5)Department of Biology, Washington University in St. Louis, St. Louis,
Missouri 63130.
Protein ubiquitylation profoundly expands proteome functionality and diversifies
cellular signaling processes, with recent studies providing ample evidence for
its importance to plant immunity. To gain a proteome-wide appreciation of
ubiquitylome dynamics during immune recognition, we employed a two-step affinity
enrichment protocol based on a 6His-tagged ubiquitin (Ub) variant coupled with
high sensitivity mass spectrometry to identify Arabidopsis proteins rapidly
ubiquitylated upon plant perception of the microbe-associated molecular pattern
(MAMP) peptide flg22. The catalog from 2-week-old seedlings treated for 30 min
with flg22 contained 690 conjugates, 64 Ub footprints, and all seven types of Ub
linkages, and included previously uncharacterized conjugates of immune
components. In vivo ubiquitylation assays confirmed modification of several
candidates upon immune elicitation, and revealed distinct modification patterns
and dynamics for key immune components, including poly- and monoubiquitylation,
as well as induced or reduced levels of ubiquitylation. Gene ontology and
network analyses of the collection also uncovered rapid modification of the
Ub-proteasome system itself, suggesting a critical auto-regulatory loop
necessary for an effective MAMP-triggered immune response and subsequent disease
resistance. Included targets were UBIQUITIN-CONJUGATING ENZYME 13 (UBC13) and
proteasome component REGULATORY PARTICLE NON-ATPASE SUBUNIT 8b (RPN8b), whose
subsequent biochemical and genetic analyses implied negative roles in immune
elicitation. Collectively, our proteomic analyses further strengthened the
connection between ubiquitylation and flg22-based immune signaling, identified
components and pathways regulating plant immunity, and increased the database of
ubiquitylated substrates in plants.
Published by Oxford University Press on behalf of American Society of Plant
Biologists 2021.
DOI: 10.1093/plphys/kiab011
PMCID: PMC8133637
PMID: 33793954 [Indexed for MEDLINE]
