Acetylation at Lysine 86 of Escherichia coli HUβ Modulates the DNA-Binding Capability of the Protein

DNA-binding protein HU is highly conserved in bacteria and has been implicated in a range of cellular processes and phenotypes. Like eukaryotic histones, HU is subjected to post-translational modifications. Specifically, acetylation of several lysine residues have been reported in both homologs of Escherichia coli HU. Here, we investigated the effect of acetylation at Lys67 and Lys86, located in the DNA binding-loop and interface of E. coli HU beta, respectively. Using the technique of genetic code expansion, homogeneous HU beta(K67ac) and HU beta(K86ac) protein units were obtained. Acetylation at Lys86 seemed to have negligible effects on protein secondary structure and thermal stability. Nevertheless, we found that this site-specific acetylation can regulate DNA binding by the HU homodimer but not the heterodimer. Intriguingly, while Lys86 acetylation reduced the interaction of the HU homodimer with short double-stranded DNA containing a 2-nucleotide gap or nick, it enhanced the interaction with longer DNA fragments and had minimal effect on a short, fully complementary DNA fragment. These results demonstrate the complexity of post-translational modifications in functional regulation, as well as indicating the role of lysine acetylation in tuning bacterial gene transcription and epigenetic regulation.

Automated summary

This study investigates the effect of lysine acetylation on the DNA-binding protein HU in bacteria. The researchers found that acetylation at Lys86 can regulate the DNA binding ability of the HU homodimer. Specifically, Lys86 acetylation reduced the interaction with short double-stranded DNA containing a gap or nick, while enhancing the interaction with longer DNA fragments. These findings demonstrate the complexity of post-translational modifications and the role of lysine acetylation in bacterial gene transcription and epigenetic regulation.