Biotin attachment domain-containing proteins mediate hydroxy fatty acid-dependent inhibition of acetyl CoA carboxylase. Issue 3 (23rd January 2021)

• Record Type: Journal Article
• Authors: Yu, Xiao-Hong; Cai, Yuanheng; Keereetaweep, Jantana; Wei, Kenneth; Chai, Jin; Deng, Elen; Liu, Hui; Shanklin, John
• Is Part Of: Plant physiology. Volume 185:Issue 3(2021)
• Page Start: 892
• Page End: 901
• Publication Date: 2021-01-23
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1093/plphys/kiaa109
• Languages: English
• ISSNs: 0032-0889

Abstract

Abstract: Hundreds of naturally occurring specialized fatty acids (FAs) have potential as desirable chemical feedstocks if they could be produced at large scale by crop plants; however, transgenic expression of their biosynthetic genes has generally been accompanied by dramatic reductions in oil yield. For example, expression of castor ( Ricinus communis ) FA hydroxylase (FAH) in the Arabidopsis thaliana FA elongation mutant fae1 resulted in a 50% reduction of FA synthesis rate that was attributed to inhibition of acetyl-CoA carboxylase (ACCase) by an undefined mechanism. Here, we tested the hypothesis that the ricinoleic acid-dependent decrease in ACCase activity is mediated by biotin attachment domain-containing (BADC) proteins. BADCs are inactive homologs of biotin carboxy carrier protein that lack a biotin cofactor and can inhibit ACCase. Arabidopsis contains three BADC genes. To reduce expression levels of BADC1 and BADC3 in fae1 /FAH plants, a homozygous badc1, 3/fae1/ FAH line was created. The rate of FA synthesis in badc1, 3/fae1/ FAH seeds doubled relative to fae1/ FAH, restoring it to fae1 levels, increasing both native FA and HFA accumulation. Total FA per seed, seed oil content, and seed yield per plant all increased in badc1, 3/fae1/ FAH, to 5.8 µg, 37%, and 162 mg, respectively, relative to 4.9 µg, 33%, and 126 mg, respectively, for fae1 /FAH. Transcript levels of FA synthesis-related genes, including those encoding ACCase subunits, did not significantly differ between badc1, 3/fae1/ FAH and fae1 /FAH. These results demonstrate that BADC1 and BADC3 mediate ricinoleic acid-dependent inhibition of FA synthesis. We propose that BADC-mediated FAS inhibition as a general mechanism that limits FA accumulation in specialized FA-accumulating seeds.