Characterization of Helianthus annuus Lipoic Acid Biosynthesis: The Mitochondrial Octanoyltransferase and Lipoyl Synthase Enzyme System

Abstract

Lipoic acid (LA, 6,8-dithiooctanoic acid) is a sulfur containing coenzyme essential for the activity of several key enzymes involved in oxidative and single carbon metabolism in most bacteria and eukaryotes. LA is synthetized by the concerted activity of the octanoyltransferase (LIP2, EC 2.3.1.181) and lipoyl synthase (LIP1, EC 2.8.1.8) enzymes. In plants, pyruvate dehydrogenase (PDH), 2-oxoglutarate dehydrogenase or glycine decarboxylase are essential complexes that need to be lipoylated. These lipoylated enzymes and complexes are located in the mitochondria, while PDH is also present in plastids where it provides acetyl-CoA for de novo fatty acid biosynthesis. As such, lipoylation of PDH could regulate fatty acid synthesis in both these organelles. In the present work, the sunflower LIP1 and LIP2 genes (HaLIP1m and HaLIP2m) were isolated sequenced, cloned, and characterized, evaluating their putative mitochondrial location. The expression of these genes was studied in different tissues and protein docking was modeled. The genes were also expressed in Escherichia coli and Arabidopsis thaliana, where their impact on fatty acid and glycerolipid composition was assessed. Lipidomic studies in Arabidopsis revealed lipid remodeling in lines overexpressing these enzymes and the involvement of both sunflower proteins in the phenotypes observed is discussed in the light of the results obtained.

Nutritional Genomic Approach for Improving Grain Protein Content in Wheat

“…The stable significant SNP ( BS00062734_51 ) on chromosome 3B identified in this study is located within a gene ( TraesCS3B02G339000 ) that encodes for a plastidial lipoyl synthase ( Table 2 and Table S5 ), a protein responsible for the biosynthesis of lipoic acid and further involved in a rare but highly conserved lysine post-translational modification, known as protein lipoylation [ 61 ]. Interestingly, BS00062734_51 was previously reported as the most significant marker in a QTL region on 3B for grain yield and duration of pre-anthesis sub-phases in a set of 210 winter genotypes selected from the GABI_WHEAT population [ 62 ].…”

Foliar Application of Sulfur-Containing Compounds—Pros and Cons

“…The nature and action of lipoic acid. LA (6,8-dithiooctanoic acid) is a S-containing compound with powerful oxidizing properties in both of its forms, the reduced dihydrolipoic acid (DHLA) and the oxidized one (LA) [168][169][170][171]. It is a coenzyme of several key enzymes involved in the regulation of the redox status of plants, and the energy metabolism in eukaryotes [170,171].…”

“…LA (6,8-dithiooctanoic acid) is a S-containing compound with powerful oxidizing properties in both of its forms, the reduced dihydrolipoic acid (DHLA) and the oxidized one (LA) [168][169][170][171]. It is a coenzyme of several key enzymes involved in the regulation of the redox status of plants, and the energy metabolism in eukaryotes [170,171]. It plays a significant role as a cofactor for pyruvate dehydrogenase and glycine decarboxylase, components of certain mitochondrial enzyme complexes [172].…”

Biomarkers and Inflammatory Pathways in Diabetes Mellitus Progression

“…Phospholipid irregularities are associated with diabetes and obesity, and monitoring these pathways in the beginning stages of diabetes could be beneficial to the treatment and diagnosis of patients 31,32 . Lipoate biosynthesis/incorporation II is the process that details the generation of lipoate, an organosulfur compound that is a critical cofactor to many enzyme complexes involved in oxidative metabolism, such as pyruvate dehydrogenase, 2-oxoglutarate dehydrogenase, branched-chain 2-oxoacid hydrogenase, acetoin dehydrogenase, and the glycine cleavage system 33 . In brief, octanoyl-ACP, a substrate of a two-step reaction catalyzed by octanoyl-transferase (LIP2) and lipoyl synthase (LIP1), generates lipoic aid as a result of β-ketoacyl-(ACP) synthase activity during de novo fatty acids synthesis.…”