סמינר בכימיה אורגנית: The functional roles and regulation of lysine ac(et)ylation

Abstract:

In recent years, thousands of putative lysine acylation sites have been identified, demonstrating that lysine acylation—mainly acetylation—is a widespread posttranslational modification that occurs on proteins involved in diverse cellular functions. However, the current understanding of the molecular mechanisms underlying acylation-regulated cellular processes is mainly based on acylated peptides and mutated proteins. Furthermore, the challenges associated with producing site-specifically acylated full-length proteins hinder our knowledge of the molecular basis of lysine deacetylases’ substrate recognition. These constraints can be alleviated by genetically encoding the site-specific incorporation of acyl-lysine derivatives into ribosomally- synthesized full-length proteins. By studying site-specifically acylated proteins, we can gain valuable structural and biochemical insights into the functional roles of single acylation events and the underlying mechanism of action. For instance, we found that acetylation can have a dual effect on G6PD, leading to its activation or inhibition, whereas 2-hydroxyisobutyrylation exclusively inhibits G6PD activity. Structural studies have elucidated that acetylation-induced inactivation of G6PD is attributed to distortions in its dimeric structure and active site. We also found that site-specific acetylation enables isoform-specific inhibition of pyruvate kinase, leading to inhibition of PKM2 and not PKM1. The genetic encoding of non-canonical amino acids also allows the investigation of deacylation processes mediated by lysine deacetylases and the design of suicide substrates targeting zinc-dependent deacetylases. These studies highlight the regulatory roles of lysine acylation and the advantage of studying proteins with genetically encoded posttranslational modifications.