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The ER luminal C‐terminus of AtSec62 is critical for male fertility and plant growth in Arabidopsis thaliana
Author(s) -
Mitterreiter Melanie Jasmine,
Bosch Franziska Annamaria,
Brylok Thomas,
Schwenkert Serena
Publication year - 2020
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.14483
Subject(s) - arabidopsis , translocon , endoplasmic reticulum , microbiology and biotechnology , biology , mutant , chaperone (clinical) , arabidopsis thaliana , chromosomal translocation , c terminus , sec61 , endoplasmic reticulum associated protein degradation , transmembrane domain , unfolded protein response , biochemistry , gene , medicine , amino acid , pathology
Summary Protein translocation into the endoplasmic reticulum (ER) occurs either co‐ or post‐translationally through the Sec translocation system. The Arabidopsis Sec post‐translocon is composed of the protein‐conducting Sec61 complex, the chaperone‐docking protein At TPR 7, the J‐domain‐containing proteins At ER dj2A/B and the yet uncharacterized AtSec62. Yeast Sec62p is suggested to mainly function in post‐translational translocation, whereas mammalian Sec62 also interacts with ribosomes. In Arabidopsis , loss of AtSec62 leads to impaired growth and drastically reduced male fertility indicating the importance of AtSec62 in protein translocation and subsequent secretion in male gametophyte development. Moreover, AtSec62 seems to be divergent in function as compared with yeast Sec62p, since we were not able to complement the thermosensitive yeast mutant sec62‐ts . Interestingly, AtSec62 has an additional third transmembrane domain in contrast to its yeast and mammalian counterparts resulting in an altered topology with the C‐terminus facing the ER lumen instead of the cytosol. In addition, the AtSec62 C‐terminus has proven to be indispensable for AtSec62 function, since a construct lacking the C‐terminal region was not able to rescue the mutant phenotype in Arabidopsis . We thus propose that Sec62 acquired a unique topology and function in protein translocation into the ER in plants.