Publication Information
Mielke et al., 2020
Abstract
J Exp Bot. 2021 Apr 13;72(9):3455-3473. doi: 10.1093/jxb/eraa550.
Abundance of metalloprotease FtsH12 modulates chloroplast development in
Arabidopsis thaliana.
Mielke K(1), Wagner R(1), Mishra LS(1), Demir F(2), Perrar A(2), Huesgen
PF(2)(3)(4), Funk C(1).
Author information:
(1)Department of Chemistry, Umeå University, Umeå, Sweden.
(2)Central Institute for Engineering, Electronics and Analytics, Jülich,
Germany.
(3)CECAD, Medical Faculty and University Hospital, University of Cologne,
Cologne, Germany.
(4)Institute of Biochemistry, University of Cologne, Cologne, Germany.
The ATP-dependent metalloprotease FtsH12 (filamentation temperature sensitive
protein H 12) has been suggested to participate in a heteromeric motor complex,
driving protein translocation into the chloroplast. FtsH12 was immuno-detected
in proplastids, seedlings, leaves, and roots. Expression of Myc-tagged FtsH12
under its native promotor allowed identification of FtsHi1, 2, 4, and 5, and
plastidic NAD-malate dehydrogenase, five of the six interaction partners in the
suggested import motor complex. Arabidopsis thaliana mutant seedlings with
reduced FTSH12 abundance exhibited pale cotyledons and small, deformed
chloroplasts with altered thylakoid structure. Mature plants retained these
chloroplast defects, resulting in slightly variegated leaves and lower
chlorophyll content. Label-free proteomics revealed strong changes in the
proteome composition of FTSH12 knock-down seedlings, reflecting impaired plastid
development. The composition of the translocon on the inner chloroplast membrane
(TIC) protein import complex was altered, with coordinated reduction of the
FtsH12-FtsHi complex subunits and accumulation of the 1 MDa TIC complex subunits
TIC56, TIC214 and TIC22-III. FTSH12 overexpressor lines showed no obvious
phenotype, but still displayed distinct differences in their proteome.
N-terminome analyses further demonstrated normal proteolytic maturation of
plastid-imported proteins irrespective of FTSH12 abundance. Together, our data
suggest that FtsH12 has highest impact during seedling development; its
abundance alters the plastid import machinery and impairs chloroplast
development.
© The Author(s) 2020. Published by Oxford University Press on behalf of the
Society for Experimental Biology.
DOI: 10.1093/jxb/eraa550
PMCID: PMC8042743
PMID: 33216923 [Indexed for MEDLINE]
