Arabidopsis clathrin adaptor EPSIN1 but not MODIFIED TRANSPORT TO THE VACOULE1 contributes to effective plant immunity against pathogenic Pseudomonas bacteria

ABSTRACT

In eukaryotes, EPSINs are Epsin N-terminal Homology (ENTH) domain-containing proteins that serve as monomeric clathrin adaptors at the plasma membrane (PM) or the trans-Golgi Network (TGN)/early endosomes (EE). The model plant Arabidopsis thaliana encodes for seven ENTH proteins, of which so far, only AtEPSIN1 (AtEPS1) and MODIFIED TRANSPORT TO THE VACUOLE1 (AtMTV1) localize to the TGN/EE and contribute to cargo trafficking to both the cell surface and the vacuole. However, relatively little is known about role(s) of any plant EPSIN in governing physiological responses. We have recently shown that AtEPS1 is a positive modulator of plant immune signaling and pattern-triggered immunity against flagellated Pseudomonas syringae pv. tomato (Pto) DC3000 bacteria. In eps1 mutants, impaired immune responses correlate with reduced accumulation of the receptor FLAGELLIN SENSING2 (AtFLS2) and the convergent immune co-receptor BRASSINOSTEROID INSENTIVE1-ASSOCIATED RECEPTOR KINASE1 (AtBAK1) in the PM. Here, we report that in contrast to AtEPS1, the TGN/EE-localized AtMTV1 did not contribute significantly to immunity against pathogenic Pto DC3000 bacteria. We also compared the amino acid sequences, peptide motif structures and in silico tertiary structures of the ENTH domains of AtEPS1 and AtMTV1 in more detail. We conclude that despite sharing the classical tertiary alpha helical ENTH-domain structure and clathrin-binding motifs, the overall low amino acid identity and differences in peptide motifs may explain their role(s) in trafficking of some of the same as well as distinct cargo components to their site of function, with the latter potentially contributing to differences in physiological responses.

KEYWORDS:

• Clathrin
• plant immunity
• EPS1
• MTV1
• ENTH
• flg22
• FLS2

Acknowledgments

The authors thank the Heese lab [University of Missouri (MU)] for discussions. This work was supported by grants and fellowship from the National Science Foundation (NSF)-Plant Biotic Interactions under grant number 1758843 (to AH); NSF-Graduate Research Fellowship under grant number 1443129 (to ELM); Deutsche Forschungsgemeinschaft (DFG) SA2427/2-1 (to MS); the MU Life Science Fellowship (to KM) and the MU Wayne L. Ryan Fellowship (to KM).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15592324.2022.2163337

Additional information

Funding

This work was supported by the Deutsche Forschungsgemeinschaft [SA2427/2-1]; National Science Foundation (NSF) - Plant Biotic Interactions [1758843]; National Science Foundation - Graduate Research Fellowship [1443129].