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A HemK class glutamine‐methyltransferase is involved in the termination of translation and essential for iron homeostasis in Arabidopsis
Author(s) -
Kailasam Sakthivel,
Singh Surjit,
Liu MingJung,
Lin ChihChing,
Yeh KuoChen
Publication year - 2020
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.16440
Subject(s) - nrf1 , arabidopsis , biology , mutant , microbiology and biotechnology , ribosome , biochemistry , arabidopsis thaliana , gene , gene expression , rna
Summary Iron (Fe) transport and utilization are controlled by Fe‐dependent transcriptional cascades. Many genes participate in these processes, transcriptionally controlled by Fe‐status. Thorough knowledge of the translational check‐points is lacking. We identified a non‐response to Fe‐deficiency1 ‐ 1 ( nrf1‐1 ) mutant of Arabidopsis thaliana , which displayed a hypersensitive phenotype under Fe‐deficient conditions. By mapping nrf1‐1 , we found that the AT3G13440 locus encoding a HemK methyltransferase is responsible for the phenotype. Analyses of ProUBQ10:NRF1 CDS overexpression nrf1‐1 lines and a T‐DNA insertion mutant nrf1‐2 , confirmed that loss‐of‐function of NRF1 results in enhanced Fe‐starvation‐sensitivity. NRF1 is required for the proper expression of the majority of Fe‐deficiency‐inducible (FDI) genes. The nrf1 mutants accumulated more polysomes in the roots, due to stalled ribosomes on several transcripts. Ribosome‐footprint (RF) mapping revealed that ribosomes are stalled at a stop codon that amplified the stalling of trailing ribosomes. We detected higher RF levels in many FDI transcripts in nrf1‐2 . Our study demonstrates the requirement of NRF1 for an accurate termination of protein synthesis essential not only for a precise iron homeostasis, but also cellular ion balance. NRF1 is also important for normal growth and development. A check‐point that fine‐tunes peptide release in plants is uncovered.