Characterization of a lipoate-protein ligase A gene of rice (Oryza sativa L.)

Lipoic acid is an essential disulfide cofactor required for the lipoate-dependent enzymes including pyruvate dehydrogenase (PDH), alpha-ketoglutarate dehydrogenase (KGDH), and glycine cleavage enzymes that function in key metabolic pathways in most prokaryotes and eukaryotes. Lipoic acid is covalently bound to lipoate-dependent enzymes by lipoate-protein ligase or lipoate transferase. Here, we characterized a lipoyl-protein ligase A (OsLPLA) gene of rice. The OsLPLA gene, which encoded 270 amino acids, was located on an approximately 21 Mb of chromosome 8 on the physical map of Oryza sativa Japonica type. OsLPLA transcripts were abundantly expressed in leaves and developing seeds. The OsLPLA gene functionally complemented an Escherichia coli lplA null mutant. Furthermore, the protein expressed from the OsLPLA gene in an E. coli lplA mutant successfully transferred exogenous lipoate to lipoate-dependent enzymes, including the E2 subunits of the PDH, the E2 subunit of KGDH and the H-protein of glycine decarboxylase, confirming that rice OsLPLA successfully catalyzed covalent attachment of lipoate onto lipoate-dependent enzymes.