key term - $\beta$-hydroxyacyl ACP dehydratase

Definition

$\beta$-hydroxyacyl ACP dehydratase is an enzyme that plays a crucial role in the biosynthesis of fatty acids. It catalyzes the dehydration step, removing water from the $\beta$-hydroxyacyl intermediate to form the $\alpha,\beta$-unsaturated acyl-ACP species, a key intermediate in the fatty acid elongation cycle.

5 Must Know Facts For Your Next Test

1. The $\beta$-hydroxyacyl ACP dehydratase enzyme is part of the type II fatty acid synthase (FAS) system found in bacteria, plants, and some eukaryotes.
2. This enzyme catalyzes the removal of water from the $\beta$-hydroxyacyl-ACP intermediate, forming the $\alpha,\beta$-unsaturated acyl-ACP species.
3. The dehydration reaction is an essential step in the fatty acid elongation cycle, allowing the continued growth of the fatty acid chain.
4. The $\alpha,\beta$-unsaturated acyl-ACP product is then further modified by other FAS enzymes, such as the enoyl-ACP reductase, to complete the elongation cycle.
5. Disruption of the $\beta$-hydroxyacyl ACP dehydratase enzyme can lead to the accumulation of $\beta$-hydroxyacyl-ACP intermediates and impair fatty acid biosynthesis.

Review Questions

• Explain the role of $\beta$-hydroxyacyl ACP dehydratase in the fatty acid biosynthesis pathway.
  • The $\beta$-hydroxyacyl ACP dehydratase enzyme catalyzes the dehydration step in the fatty acid elongation cycle, where it removes a molecule of water from the $\beta$-hydroxyacyl-ACP intermediate to form the $\alpha,\beta$-unsaturated acyl-ACP species. This dehydration reaction is a crucial step that allows the continued growth and elongation of the fatty acid chain by the fatty acid synthase complex. Without the activity of $\beta$-hydroxyacyl ACP dehydratase, the fatty acid biosynthesis pathway would be disrupted, leading to the accumulation of $\beta$-hydroxyacyl-ACP intermediates and impaired fatty acid production.
• Describe the relationship between $\beta$-hydroxyacyl ACP dehydratase and the type II fatty acid synthase (FAS) system.
  • The $\beta$-hydroxyacyl ACP dehydratase enzyme is an integral component of the type II fatty acid synthase (FAS) system, which is found in bacteria, plants, and some eukaryotes. The type II FAS system is characterized by discrete, individual enzymes that work together to catalyze the stepwise synthesis of fatty acids. $\beta$-hydroxyacyl ACP dehydratase is one of these enzymes, responsible for the dehydration step in the fatty acid elongation cycle. Its activity is essential for the continued growth and modification of the fatty acid chain by the other FAS enzymes, making it a critical player in the overall fatty acid biosynthesis pathway.
• Analyze the potential consequences of disrupting the $\beta$-hydroxyacyl ACP dehydratase enzyme in the context of fatty acid biosynthesis.
  • If the $\beta$-hydroxyacyl ACP dehydratase enzyme is disrupted or inhibited, it would lead to the accumulation of the $\beta$-hydroxyacyl-ACP intermediate in the fatty acid biosynthesis pathway. This would impair the ability of the fatty acid synthase complex to continue the elongation and modification of the fatty acid chain, effectively halting the overall fatty acid biosynthesis process. The inability to produce essential fatty acids would have far-reaching consequences for the organism, as fatty acids are critical components of cell membranes, signaling molecules, and energy storage. Disrupting $\beta$-hydroxyacyl ACP dehydratase could therefore be a potential target for antimicrobial or herbicidal compounds, as it would disrupt a key step in the fundamental process of fatty acid synthesis.

Related terms

Acyl Carrier Protein (ACP): ACP is a small, acidic protein that serves as a cofactor, carrying the growing fatty acid chain during the biosynthesis process.

Fatty Acid Synthase (FAS): FAS is a multi-enzyme complex responsible for the de novo synthesis of fatty acids from acetyl-CoA and malonyl-CoA precursors.

Fatty Acid Elongation Cycle: The cyclic process of adding two-carbon units to the growing fatty acid chain, catalyzed by the enzymes of the fatty acid synthase complex.