3-oxoacyl-(acyl-carrier-protein) reductase

3-oxoacyl-(acyl-carrier-protein) reductase

3-oxoacyl-(acyl-carrier-protein) reductase (also known as FabG) is an essential enzyme involved in the fatty acid biosynthesis pathway in bacteria. It catalyzes the reduction of 3-oxoacyl-ACP to 3-hydroxyacyl-ACP, a crucial step in the elongation of fatty acids. This enzyme plays a vital role in the production of cellular membranes and energy storage in bacteria.

Structure

The 3-oxoacyl-(acyl-carrier-protein) reductase enzyme is typically composed of a single polypeptide chain, ranging from 250 to 350 amino acids in length. It contains a conserved NAD(P)H-binding domain, which is responsible for the reduction of the substrate. The active site of the enzyme consists of a catalytic triad, usually composed of a serine, tyrosine, and lysine residue, which is involved in the catalytic mechanism.

Function

The primary function of 3-oxoacyl-(acyl-carrier-protein) reductase is to reduce the 3-oxoacyl-ACP intermediate to 3-hydroxyacyl-ACP during fatty acid biosynthesis. This reduction step is crucial for the elongation of fatty acids, as it provides the necessary hydroxyl group for further modifications. The enzyme utilizes NAD(P)H as a cofactor to transfer electrons and facilitate the reduction reaction.

Role in Fatty Acid Biosynthesis

Fatty acid biosynthesis is a complex metabolic pathway that occurs in bacteria, plants, and animals. In bacteria, this pathway takes place in the cytoplasm and involves a series of enzymatic reactions. 3-oxoacyl-(acyl-carrier-protein) reductase is one of the key enzymes involved in this pathway.

During fatty acid biosynthesis, the growing fatty acid chain is attached to an acyl carrier protein (ACP). The ACP carries the fatty acid intermediate from one enzyme to another, facilitating the elongation process. 3-oxoacyl-(acyl-carrier-protein) reductase acts on the 3-oxoacyl-ACP intermediate, reducing it to 3-hydroxyacyl-ACP. This hydroxylation step allows for further modifications and elongation of the fatty acid chain.

Importance in Bacterial Physiology

The activity of 3-oxoacyl-(acyl-carrier-protein) reductase is essential for bacterial physiology and survival. Fatty acids are crucial components of cellular membranes, providing structural integrity and fluidity. Additionally, fatty acids serve as a source of energy storage in the form of triglycerides.

Inhibition or disruption of 3-oxoacyl-(acyl-carrier-protein) reductase activity can have detrimental effects on bacterial growth and viability. This enzyme has been identified as a potential target for the development of antibacterial agents, as its inhibition can disrupt fatty acid biosynthesis and lead to bacterial cell death.

References

1. Zhang YM, Rock CO. (2008). Membrane lipid homeostasis in bacteria. Nat Rev Microbiol. 6(3):222-33. doi: 10.1038/nrmicro1839.

2. Heath RJ, Rock CO. (2002). A conserved histidine is essential for glycerolipid acyltransferase catalysis. J Bacteriol. 184(1):299-302. doi: 10.1128/jb.184.1.299-302.2002.

See Also

• Fatty acid biosynthesis
• Acyl carrier protein
• NAD(P)H