Arabidopsis HIPP proteins regulate endoplasmic reticulum-associated degradation of CIOX proteins and cytokinin responses

0552834 - ÚEB 2022 RIV GB eng J - Journal Article
Guo, T. - Weber, H. - Niemann, M. - Theisl, L. - Leonte, G. - Novák, Ondřej - Werner, T.
Arabidopsis HIPP proteins regulate endoplasmic reticulum-associated degradation of CIOX proteins and cytokinin responses.
Molecular Plant. Roč. 14, č. 11 (2021), s. 1918-1934. ISSN 1674-2052. E-ISSN 1752-9867
R&D Projects: GA MŠMT(CZ) EF16_019/0000827
Institutional support: RVO:61389030
Keywords : quality control * transient expression * flowering time * root-growth * organ size * genes * plants * receptors * shoot * ER
OECD category: Biochemistry and molecular biology
Impact factor: 21.949, year: 2021
Method of publishing: Open access
http://doi.org/10.1016/j.molp.2021.07.015

Eukaryotic organisms are equipped with quality-control mechanisms that survey protein folding in the endoplasmic reticulum (ER) and remove non-native proteins by ER-associated degradation (ERAD). Recent research has shown that cytokinin-degrading CIOX proteins are subjected to ERAD during plant development. The mechanisms of plant ERAD, including the export of substrate proteins from the ER, are not fully understood, and the molecular components involved in the ERAD of CIOX are unknown. Here, we show that heavy metal-associated isoprenylated plant proteins (HIPPs) interact specifically with CIOX proteins synthesized in the ER and processed by ERAD. CIOX-HIPP protein complexes were detected at the ER as well as in the cytosol, suggesting that the complexes involve retrotranslocated CIOX protein species. Altered CIOX levels in HIPP-overexpressing and higher-order hipp mutant plants suggest that the studied HIPPs control the ERAD of CIOX. Deregulation of CIOX proteins caused corresponding changes in the cytokinin signaling activity and triggered typical morphological cytokinin responses. Notably, transcriptional repression of HIPP genes by cytokinin indicates a feedback regulatory mechanism of cytokinin homeostasis and signaling responses. Moreover, loss of function of HIPP genes constitutively activates the unfolded protein response and compromises the ER stress tolerance. Collectively, these results suggests that HIPPs represent novel functional components of plant ERAD.
Permanent Link: http://hdl.handle.net/11104/0327928