A type II secreted subtilase from commensal rhizobacteria cleaves immune elicitor peptides and suppresses flg22-induced immune activation
Samuel Eastman,
Ting Jiang,
Kaeli Ficco,
Chao Liao,
Britley Jones,
Sarina Wen,
Yvette Olivas Biddle,
Aya Eyceoz,
Ilya Yatsishin,
Todd A. Naumann,
Jonathan M. Conway
Affiliations
Samuel Eastman
Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
Ting Jiang
Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
Kaeli Ficco
Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
Chao Liao
Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
Britley Jones
Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
Sarina Wen
Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
Yvette Olivas Biddle
Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
Aya Eyceoz
Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
Ilya Yatsishin
Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
Todd A. Naumann
Mycotoxin Prevention and Applied Microbiology Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, USDA, Peoria, IL 61604, USA
Jonathan M. Conway
Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA; Omenn-Darling Bioengineering Institute, Princeton University, Princeton, NJ 08544, USA; High Meadows Environmental Institute, Princeton University, Princeton, NJ 08544, USA; Andlinger Center for Energy and the Environment, Princeton University, Princeton, NJ 08544, USA; Corresponding author
Summary: Plant roots grow in association with a community of microorganisms collectively known as the rhizosphere microbiome. Immune activation in response to elicitors like the flagellin-derived epitope flg22 restricts bacteria on plant roots but also inhibits plant growth. Some commensal root-associated bacteria are capable of suppressing the plant immune response to elicitors. In this study, we investigated the ability of 165 root-associated bacteria to suppress flg22-induced immune activation and growth restriction. We demonstrate that a type II secreted subtilase, which we term immunosuppressive subtilase A (IssA), from Dyella japonica strain MF79 cleaves the immune elicitor peptide flg22 and suppresses immune activation. IssA homologs are found in other plant-associated commensals, with particularly high conservation in the order Xanthomonadales. This represents a novel mechanism by which commensal microbes modulate flg22-induced immunity in the rhizosphere microbiome.