A novel plant actin-microtubule bridging complex regulates cytoskeletal and ER structure at ER-PM contact sites

Jingze Zang; Sandra Klemm; Charlotte Pain; Patrick Duckney; Zhiru Bao; Gina Stamm; Verena Kriechbaumer; Katharina Bürstenbinder; Patrick J Hussey; Pengwei Wang

doi:10.1016/j.cub.2020.12.009

A novel plant actin-microtubule bridging complex regulates cytoskeletal and ER structure at ER-PM contact sites

Curr Biol. 2021 Mar 22;31(6):1251-1260.e4. doi: 10.1016/j.cub.2020.12.009. Epub 2021 Feb 15.

Authors

Affiliations

¹ Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, Hubei Province, China; Interdisciplinary Sciences Research Institute, Huazhong Agricultural University, Wuhan 430007, China; Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK.
² Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, 06120 Halle, Germany.
³ Plant Cell Biology, Oxford Brookes University, Oxford OX3 0BP, UK.
⁴ Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK.
⁵ Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, Hubei Province, China; Interdisciplinary Sciences Research Institute, Huazhong Agricultural University, Wuhan 430007, China.
⁶ Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK; Department of Experimental Plant Biology, Charles University, Faculty of Science, Viničná 5, 128 43 Praha 2, Czechia. Electronic address: p.j.hussey@durham.ac.uk.
⁷ Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, Hubei Province, China; Interdisciplinary Sciences Research Institute, Huazhong Agricultural University, Wuhan 430007, China. Electronic address: wangpengwei@mail.hzau.edu.cn.

PMID: 33592189
DOI: 10.1016/j.cub.2020.12.009

Abstract

In plants, the cortical endoplasmic reticulum (ER) network is connected to the plasma membrane (PM) through the ER-PM contact sites (EPCSs), whose structures are maintained by EPCS resident proteins and the cytoskeleton.^1-7 Strong co-alignment between EPCSs and the cytoskeleton is observed in plants,¹^,⁸ but little is known of how the cytoskeleton is maintained and regulated at the EPCS. Here, we have used a yeast-two-hybrid screen and subsequent in vivo interaction studies in plants by fluorescence resonance energy transfer (FRET)-fluorescence lifetime imaging microscopy (FLIM) analysis to identify two microtubule binding proteins, KLCR1 (kinesin-light-chain-related protein 1) and IQD2 (IQ67-domain 2), that interact with the actin binding protein NET3C and form a component of plant EPCS that mediates the link between the actin and microtubule networks. The NET3C-KLCR1-IQD2 module, acting as an actin-microtubule bridging complex, has a direct influence on ER morphology and EPCS structure. Their loss-of-function mutants, net3a/NET3C RNAi, klcr1, or iqd2, exhibit defects in pavement cell morphology, which we suggest is linked to the disorganization of both actin filaments and microtubules. In conclusion, our results reveal a novel cytoskeletal-associated complex, which is essential for the maintenance and organization of cytoskeletal structure and ER morphology at the EPCS and for normal plant cell morphogenesis.

Keywords: ER network; ER-PM contact sites; IQD family; NET family; cytoskeleton; kinesin-light-chain-related proteins; plant cell morphogenesis.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Actins*
Cell Membrane*
Cytoskeleton*
Endoplasmic Reticulum*
Microtubules*
Plants*

Substances

Actins