Nuclear transport receptor KA120 regulates molecular condensation of MAC3 to coordinate plant immune activation

Min Jia; Xuanyi Chen; Xuetao Shi; Yiling Fang; Yangnan Gu

doi:10.1016/j.chom.2023.08.015

Nuclear transport receptor KA120 regulates molecular condensation of MAC3 to coordinate plant immune activation

Cell Host Microbe. 2023 Oct 11;31(10):1685-1699.e7. doi: 10.1016/j.chom.2023.08.015. Epub 2023 Sep 14.

Authors

Min Jia¹, Xuanyi Chen², Xuetao Shi³, Yiling Fang¹, Yangnan Gu⁴

Affiliations

¹ Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA 94720, USA.
² National Key Laboratory of Crop Improvement for Stress Tolerance and Production, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China.
³ Tsinghua-Peking Joint Center for Life Sciences, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
⁴ Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA 94720, USA. Electronic address: guyangnan@berkeley.edu.

PMID: 37714161
DOI: 10.1016/j.chom.2023.08.015

Abstract

The nucleocytoplasmic exchange is of fundamental importance to eukaryotic life and is mediated by karyopherins, a superfamily of nuclear transport receptors. However, the function and cargo spectrum of plant karyopherins are largely obscure. Here, we report proximity-labeling-based proteomic profiling of in vivo substrates of KA120, a karyopherin-β required for suppressing autoimmune induction in Arabidopsis. We identify multiple components of the MOS4-associated complex (MAC), a conserved splicing regulatory protein complex. Surprisingly, we find that KA120 does not affect the nucleocytoplasmic distribution of MAC proteins but rather prevents their protein condensation in the nucleus. Furthermore, we demonstrate that MAC condensation is robustly induced by pathogen infection, which is sufficient to activate defense gene expression, possibly by sequestrating negative immune regulators via phase transition. Our study reveals a noncanonical chaperoning activity of a plant karyopherin, which modulates the nuclear condensation of an evolutionarily conserved splicing regulatory complex to coordinate plant immune activation.

Keywords: KA120; MAC; MAC3; MOS4-associated complex; biomolecular condensation; karyopherin; nuclear condensates; nuclear transport receptor; plant immunity.