In plants, light-dependent activation of de novo fatty acid synthesis
(FAS) is partially mediated by acetyl-CoA carboxylase (ACCase), the
first committed step for this pathway. However, it is not fully
understood how plants control light-dependent FAS regulation to meet the
cellular demand for acyl chains.

We report here the identification of a gene family encoding for three
small plastidial proteins of the envelope membrane that interact with
the �?-carboxyltransferase (�?-CT) subunit of ACCase and participate in an
original mechanism restraining FAS in the light.

Light enhances the interaction between carboxyltransferase interactors
(CTIs) and �?-CT, which in turn attenuates carbon flux into FAS.
Knockouts for CTI exhibit higher rates of FAS and marked increase in
absolute triacylglycerol levels in leaves, more than 4-fold higher than
in wild-type plants. Furthermore, WRINKLED1, a master transcriptional
regulator of FAS, positively regulates/CTI1/expression by direct binding
to its promoter.

This study reveals that in addition to light-dependent activation,
�??envelope docking�?� of ACCase permits fine-tuning of fatty acid supply
during the plant life cycle.

Docking of acetyl-CoA carboxylase to the plastid envelope membrane
attenuates fatty acid production in plants | Nature Communications
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