AUTHOR=Hu Shu-Hsuan , Lin Shu-Fan , Huang Ya-Chen , Huang Chien-Hsun , Kuo Wen-Yu , Jinn Tsung-Luo 

TITLE=Significance of AtMTM1 and AtMTM2 for Mitochondrial MnSOD Activation in Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.690064

DOI=10.3389/fpls.2021.690064

ISSN=1664-462X

ABSTRACT=<p>The manganese (Mn) tracking factor for mitochondrial Mn superoxide dismutase (MnSOD) has been annotated as yMTM1 in yeast, which belongs to the mitochondrial carrier family. We confirmed that <italic>Arabidopsis</italic> AtMTM1 and AtMTM2 are functional homologs of yMTM1 as they can revive yeast MnSOD activity in <italic>yMTM1</italic>-mutant cells. Transient expression of AtMnSOD-3xFLAG in the <italic>AtMTM1</italic> and <italic>AtMTM2</italic>-double mutant protoplasts confirmed that AtMTM1 and AtMTM2 are required for AtMnSOD activation. Our study revealed that AtMnSOD interacts with AtMTM1 and AtMTM2 in the mitochondria. The expression levels of <italic>AtMTM1</italic>, <italic>AtMTM2</italic>, and <italic>AtMnSOD</italic> respond positively to methyl viologen (MV) and metal stress. AtMTM1 and AtMTM2 are involved in Mn and Fe homeostasis, root length, and flowering time. Transient expression of chloroplast-destined AtMnSOD revealed that an evolutionarily conserved activation mechanism, like the chloroplastic-localized MnSOD in some algae, still exists in <italic>Arabidopsis</italic> chloroplasts. This study strengthens the proposition that AtMTM1 and AtMTM2 participate in the AtMnSOD activation and ion homeostasis.</p>