Reference "Identification of mitochondrial thiamin diphosphate carriers from Arabidopsis and maize"

Reference ID

54990

Title

Identification of mitochondrial thiamin diphosphate carriers from Arabidopsis and maize

Source

Funct Integr Genomics, 2012, vol. 12, pp. 317-326

Authors (9)

Frelin-O	Agrimi-G
Laera-V-L	Castegna-A
Richardson-L-G	Mullen-R-T
Lerma-Ortiz-C	Palmieri-F
Hanson-A-D

Abstract

It is currently held that thiamin is made in chloroplasts and converted in the
cytosol to the active cofactor thiamin diphosphate (ThDP), and that mitochondria
and plastids import ThDP. The organellar transporters that mediate ThDP import
in plants have not been identified. Comparative genomic analysis indicated that
two members of the mitochondrial carrier family (MCF) in Arabidopsis (At5g48970
and At3g21390) and two in maize (GRMZM2G118515 and GRMZM2G124911) are related to
the ThDP carriers of animals and Saccharomyces cerevisiae. Expression of each of
these plant proteins in a S. cerevisiae ThDP carrier (TPC1) null mutant
complemented the growth defect on fermentable carbon sources and restored the
level of mitochondrial ThDP and the activity of the mitochondrial ThDP-dependent
enzyme acetolactate synthase. The plant proteins were targeted to mitochondria
as judged by dual import assays with purified pea mitochondria and chloroplasts,
and by microscopic analysis of the subcellular localization of green fluorescent
protein fusions in transiently transformed tobacco suspension cells. Both maize
genes were shown to be expressed throughout the plant, which is consistent with
the known ubiquity of mitochondrial ThDP-dependent enzymes. Collectively, these
data establish that plants have mitochondrially located MCF carriers for ThDP,
and indicate that these carriers are highly evolutionarily conserved. Our data
provide a firm basis to propagate the functional annotation of mitochondrial
ThDP carriers to other angiosperm genomes.