histone H4K5 acetyltransferase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: acetyl-CoA + histone H4 L-lysine (position 5) = CoA + histone H4 N6-acetyl-L-lysine (position 5). [EC:2.3.1.48]

Histone H4K5 acetyltransferase activity refers to the enzymatic ability of certain proteins to catalyze the transfer of an acetyl group from acetyl coenzyme A (acetyl-CoA) to the epsilon-amino group of lysine 5 (K5) on histone H4. This modification is a key component of epigenetic regulation, influencing gene expression and other cellular processes.

Here's a detailed explanation of the molecular function:

1. **Substrate Recognition:** The acetyltransferase recognizes and binds to histone H4, specifically targeting the lysine 5 residue. This interaction involves specific amino acid sequences and electrostatic interactions that create a binding pocket for the histone.

2. **Acetyl-CoA Binding:** The acetyltransferase binds to acetyl-CoA, the donor molecule carrying the acetyl group. The enzyme's active site contains a cysteine residue that forms a thioester bond with the acetyl group, preparing it for transfer.

3. **Catalysis:** Through a complex series of steps, the acetyltransferase facilitates the transfer of the acetyl group from acetyl-CoA to the lysine 5 residue on histone H4. This involves nucleophilic attack by the epsilon-amino group of lysine 5 on the acetyl group, releasing CoA and forming an acetylated lysine residue.

4. **Product Release:** After acetylation, the enzyme releases the modified histone H4, allowing it to interact with other proteins or DNA.

**Significance of H4K5 Acetylation:**

* **Gene Regulation:** Acetylation of histone H4 at lysine 5 is associated with increased gene expression. It typically alters chromatin structure, making DNA more accessible to transcription factors and promoting transcription initiation.
* **Chromatin Remodeling:** This modification can influence the recruitment of other proteins involved in chromatin remodeling, such as ATP-dependent chromatin remodelers. These proteins can reposition nucleosomes, altering the accessibility of DNA and regulating gene expression.
* **Cellular Processes:** H4K5 acetylation is implicated in various cellular processes, including development, cell cycle regulation, and response to stress. It plays a role in maintaining genomic stability, DNA repair, and cell differentiation.

**Note:** Specific acetyltransferases responsible for H4K5 acetylation and their regulatory mechanisms are being actively investigated, and the exact roles of this modification in different cellular contexts continue to be explored.'
"

Proteins (5)

Compounds (18)