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A phosphopantetheinyl transferase that is essential for mitochondrial fatty acid biosynthesis
Author(s) -
Guan Xin,
Chen Hui,
Abramson Alex,
Man Huimin,
Wu Jinxia,
Yu Oliver,
Nikolau Basil J.
Publication year - 2015
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.13034
Subject(s) - arabidopsis , biology , biochemistry , acyl carrier protein , photorespiration , glycine cleavage system , arabidopsis thaliana , fatty acid synthase , mutant , mitochondrion , fatty acid synthesis , transferase , biosynthesis , glycine , fatty acid , enzyme , gene , amino acid
Summary In this study we report the molecular genetic characterization of the Arabidopsis mitochondrial phosphopantetheinyl transferase (mt PPT ), which catalyzes the phosphopantetheinylation and thus activation of mitochondrial acyl carrier protein (mt ACP ) of mitochondrial fatty acid synthase (mt FAS ). This catalytic capability of the purified mt PPT protein (encoded by AT 3G11470) was directly demonstrated in an in vitro assay that phosphopantetheinylated mature Arabidopsis apo‐mt ACP isoforms. The mitochondrial localization of the AT 3G11470‐encoded proteins was validated by the ability of their N‐terminal 80‐residue leader sequence to guide a chimeric GFP protein to this organelle. A T‐ DNA ‐tagged null mutant mtppt‐1 allele shows an embryo‐lethal phenotype, illustrating a crucial role of mt PPT for embryogenesis. Arabidopsis RNA i transgenic lines with reduced mt PPT expression display typical phenotypes associated with a deficiency in the mt FAS system, namely miniaturized plant morphology, slow growth, reduced lipoylation of mitochondrial proteins, and the hyperaccumulation of photorespiratory intermediates, glycine and glycolate. These morphological and metabolic alterations are reversed when these plants are grown in a non‐photorespiratory condition (i.e. 1% CO 2 atmosphere), demonstrating that they are a consequence of a deficiency in photorespiration due to the reduced lipoylation of the photorespiratory glycine decarboxylase.