Lipoyl synthase
| Lipoyl synthase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
| |||||||||
Lipoyl synthase is an
Nomenclature
The systematic name of this enzyme class is protein N6-(octanoyl)lysine:sulfur sulfurtransferase. Other names in common use include:
- LS
- LipA
- lipoate synthase
- protein 6-N-(octanoyl)lysine:sulfur sulfurtransferase.
Structure
The sequence length of M. tuberculosis lipoyl synthase is approximately 331 amino acids. The structure is composed of 11 α-helices and 7 β sheets, with multiple loop structures connecting the other components. The two [4Fe-4S] clusters are located within the structure, appearing in three-dimensional cubic shape. A molecule of DTV ((2S,3S)-1,4-Dimercaptobutane-2,3-diol), more commonly known as DTT (dithiothreitol), is also present within the structure. This molecule is responsible for protecting thiol groups from oxidation. The molecule is surrounded by water molecules as well, which form hydrogen bonds with side residues to stabilize the structure. The enzyme's structure is shown.
Mechanism of lipoyl synthase
As previously mentioned, lipoyl synthase is a member of a subfamily of the radical SAM(S-adenosyl methionine) enzyme family, which use a [4Fe-4S] cluster
Importance of lipoyl synthase
This enzyme participates in lipoic acid metabolism, where it performs the final step in lipoic acid biosynthesis. Lipoic acid is a cofactor that has different functions within different organisms.[4] The lipoic acid generation in yeast cells increases the number of divisions in the cells as well as protects yeast cells from hydrogen peroxide.[5] Lipoic acid is an important co-factor in many enzyme systems, and one of them is the pyruvate dehydrogenase complex.[6] Studies that repressed the function of lipoyl synthase in Arabidopsis thaliana seeds showed that this did not have adverse effects on seed growth and weight, but shortened the generation time as well as the flowering time of the plants. Repression resulted in earlier flowering times and decreased the generation times between seeds by almost 10%.[7]
Possible side effects of lipoyl synthase in plants
Overexpression of this enzyme in sunflower plants has been found to eventually sequester the amount of SAM present in transgenic Arabidopsis plants. SAM is a molecule that is required in other enzymatic complexes found in this plant as well, as well as the overall structure of the plant, so this sequestration may cause a reduction in the fatty acid biosynthesis in the Arabidopsis seeds.[8]
References
- PMID 27506792.
- ^ Bank, RCSB Protein Data. "RCSB PDB - 5EXI: Crystal structure of M. tuberculosis lipoyl synthase at 2.28 A resolution". www.rcsb.org. Retrieved 2023-05-10.
- PMID 25477512.
- ^ "InterPro". www.ebi.ac.uk. Retrieved 2020-04-20.
- PMID 14599473.
- ^ "Lipoic Acid". Linus Pauling Institute. 2014-04-28. Retrieved 2020-04-20.
- S2CID 8099883.
- PMID 32111914.
