The SUMO E3 Ligase MdSIZ1 Targets MdbHLH104 to Regulate Plasma Membrane H + -ATPase Activity and Iron Homeostasis

SIZ1 (a SIZ/PIAS-type SUMO E3 ligase)-mediated small ubiquitin-like modifier (SUMO) modification of target proteins is important for various biological processes related to abiotic stress resistance in plants; however, little is known about its role in resistance toward iron (Fe) deficiency. Here, t...

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Published in:Plant physiology (Bethesda) 2019-01, Vol.179 (1), p.88-106
Main Authors: Zhou, Li-Jie, Zhang, Chun-Ling, Zhang, Rui-Fen, Wang, Gui-Luan, Li, Yuan-Yuan, Hao, Yu-Jin
Format: Article
Language:English
Subjects:
Cell Membrane - metabolism
Iron - metabolism
Malus - enzymology
Malus - metabolism
Proton-Translocating ATPases - metabolism
Rhizosphere
RNA, Messenger - metabolism
Sumoylation
Ubiquitins - genetics
Ubiquitins - metabolism
Ubiquitins - physiology
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Summary:SIZ1 (a SIZ/PIAS-type SUMO E3 ligase)-mediated small ubiquitin-like modifier (SUMO) modification of target proteins is important for various biological processes related to abiotic stress resistance in plants; however, little is known about its role in resistance toward iron (Fe) deficiency. Here, the SUMO E3 ligase MdSIZ1 was shown to be involved in the plasma membrane (PM) H -ATPase-mediated response to Fe deficiency. Subsequently, a basic helix-loop-helix transcription factor, MdbHLH104 (a homolog of Arabidopsis bHLH104 in apple), which acts as a key component in regulating PM H -ATPase-mediated rhizosphere acidification and Fe uptake in apples ( ), was identified as a direct target of MdSIZ1. MdSIZ1 directly sumoylated MdbHLH104 both in vitro and in vivo, especially under conditions of Fe deficiency, and this sumoylation was required for MdbHLH104 protein stability. Double substitution of K139R and K153R in MdbHLH104 blocked MdSIZ1-mediated sumoylation in vitro and in vivo, indicating that the K139 and K153 residues were the principal sites of SUMO conjugation. Moreover, the transcript level of the gene was substantially induced following Fe deficiency. overexpression exerted a positive influence on PM H -ATPase-mediated rhizosphere acidification and Fe uptake. Our findings reveal an important role for sumoylation in the regulation of PM H -ATPase-mediated rhizosphere acidification and Fe uptake during Fe deficiency in plants.
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.18.00289