Lotus japonicus E3 Ligase SEVEN IN ABSENTIA4 Destabilizes the Symbiosis Receptor-Like Kinase SYMRK and Negatively Regulates Rhizobial Infection

Abstract

The Lotus japonicus SYMBIOSIS RECEPTOR-LIKE KINASE (SYMRK) is required for symbiotic signal transduction upon stimulation of root cells by microbial signaling molecules. Here, we identified members of the SEVEN IN ABSENTIA (SINA) E3 ubiquitin-ligase family as SYMRK interactors and confirmed their predicted ubiquitin-ligase activity. In Nicotiana benthamiana leaves, SYMRK-yellow fluorescent protein was localized at the plasma membrane, and interaction with SINAs, as determined by bimolecular fluorescence complementation, was observed in small punctae at the cytosolic interface of the plasma membrane. Moreover, fluorescence-tagged SINA4 partially colocalized with SYMRK and caused SYMRK relocalization as well as disappearance of SYMRK from the plasma membrane. Neither the localization nor the abundance of Nod-factor receptor1 was altered by the presence of SINA4. SINA4 was transcriptionally upregulated during root symbiosis, and rhizobia inoculated roots ectopically expressing SINA4 showed reduced SYMRK protein levels. In accordance with a negative regulatory role in symbiosis, infection thread development was impaired upon ectopic expression of SINA4. Our results implicate SINA4 E3 ubiquitin ligase in the turnover of SYMRK and provide a conceptual mechanism for its symbiosis-appropriate spatio-temporal containment.

A Laser Dissection-RNAseq Analysis Highlights the Activation of Cytokinin Pathways by Nod Factors in the Medicago truncatula Root Epidermis

“…The ubiquitin proteasome machinery comprises many genes involved in the regulation of signaling/ developmental processes, including response to phytohormones and positive or negative roles for rhizobium infection and nodule development (Vinardell et al, 2003;Shimomura et al, 2006;Kiss et al, 2009;Mbengue et al, 2010;Den Herder et al, 2012;Yuan et al, 2012). Nineteen putative ubiquitin proteasome genes were scored as NF up-regulated, among which two genes encoding, respectively, a close homolog of LUMPY INFECTIONS (MtLIN), primarily required for infection thread growth in RH (Kiss et al, 2009), and a nodulation-specific SEVEN-IN-ABSENTIA (SINA) domain protein, very distantly related to LjSINA4, involved in SYMRK turnover (Den Herder et al, 2012; Table III; Supplemental Table S3).…”

“…Nineteen putative ubiquitin proteasome genes were scored as NF up-regulated, among which two genes encoding, respectively, a close homolog of LUMPY INFECTIONS (MtLIN), primarily required for infection thread growth in RH (Kiss et al, 2009), and a nodulation-specific SEVEN-IN-ABSENTIA (SINA) domain protein, very distantly related to LjSINA4, involved in SYMRK turnover (Den Herder et al, 2012; Table III; Supplemental Table S3). The ortholog of AtPUB22, encoding a negative regulator of immunity (Trujillo et al, 2008), also was found to be moderately but significantly induced by NF at 24 h (Table III).…”

Proteasome‐independent functions of lysine‐63 polyubiquitination in plants

“…A number of plasma membrane receptors involved in responses to pathogens or symbiosis, together with their cognate E3 ligases, have been characterized (Kim et al, 2003;Wang et al, 2006;Mbengue et al, 2010;Lu et al, 2011;Den Herder et al, 2012;Liao et al, 2017;Fig. 5).…”

Ubiquitin on the Move: The Ubiquitin Modification System Plays Diverse Roles in the Regulation of Endoplasmic Reticulum- and Plasma Membrane-Localized Proteins

“…The abundance of SYMBIOSIS RECEPTOR-LIKE KINASE (SYMRK), a receptor-like kinase necessary for fungal and bacterial symbioses in legumes and nonlegumes, is controlled by the E3 ligase SEVEN IN ABSENTIA4 (SINA4; Den Herder et al, 2012). SINA4 presumably maintains SYMRK above the threshold to sense microbial metabolites but low enough to inhibit excessive bacterial colonization.…”