Biology subjects

Nielsen, A. L.

Publications and source records attributed to Nielsen, A. L..

3 recordsLinked to original sources

bioRxiv2023

Fluorogenic Substrates and Cyclic Peptide Inhibitors of the Oligonucleotide Activated SIRT7

The sirtuins are NAD+-dependent lysine deacylases, comprising seven isoforms (SIRT1-7) in humans, which are involved in the regulation of a plethora of biology, including gene expression and metabolism. The sirtuins share a common hydrolytic mechanism but display preferences for different {varepsilon}-N-acyllysine substrates. SIRT7 deacetylates targets in nuclei and nucleoli but remains one of the lesser studied of the seven isoforms; in part, because of a lack of chemical tools to specifically probe SIRT7 activity. Here we expressed SIRT7 and, using small-angle X-ray scattering, reveal SIRT7 to be a monomeric enzyme with low degree of globular flexibility in solution. We developed a fluorogenic assay for investigation of the substrate preferences of SIRT7 and to evaluate compounds that modulate its activity. We report several mechanism-based SIRT7 inhibitors as well as de novo cyclic peptide inhibitors selected from mRNA-display library screening that exhibit selectivity for SIRT7 over other sirtuin isoforms and stabilize SIRT7 in cells.

biochemistry↗

bioRxiv2021

Class I Histone Deacetylases (HDAC1-3) are Histone Lysine Delactylases

Lysine O_SCPLOWLC_SCPLOW-lactylation [K(O_SCPLOWLC_SCPLOW-la)] is a newly discovered histone mark that can be stimulated under conditions of high glycolysis, such as the Warburg effect. K(O_SCPLOWLC_SCPLOW-la) is associated with functions that are different from the widely studied histone acetylation. While K(O_SCPLOWLC_SCPLOW-la) can be introduced by the acetyltransferase p300, histone delactylase enzymes remain unknown. Here, we report the systematic evaluation of zinc- and NAD+-dependent HDACs for their ability to cleave {varepsilon}-N-O_SCPLOWLC_SCPLOW-lactyllysine marks. Our screens identified HDACs 1-3 and SIRT1-3 as delactylases in vitro. HDACs 1-3 show robust activity toward not only K(O_SCPLOWLC_SCPLOW-la) but also K(O_SCPLOWDC_SCPLOW-la) and diverse short-chain acyl modifications. We further confirmed the de-O_SCPLOWLC_SCPLOW-lactylase activity of HDACs 1 and 3 in cells. Identification of p300 and HDAC3 as regulatory enzymes suggests that histone lactylation is installed and removed by enzymes as opposed to spontaneous chemical reactivity. Our results therefore represent an important step toward full characterization of this pathways regulatory elements.

biochemistry↗

bioRxiv2020

Selective inhibitors of SIRT2 regulate perinuclear α-tubulin acetylation, migration, and invasion of breast cancer cells

Sirtuin 2 (SIRT2) is a protein deacylase enzyme that removes acetyl groups and longer chain acyl groups from post-translationally modified lysine residues. It affects diverse biological functions in the cell and has been considered a drug target in relation to both neurodegenerative diseases and cancer. Therefore, access to well-characterized and robust tool compounds is essential for the continued investigation of the complex functions of this enzyme. Here, we report a collection of probes that are potent, selective, stable in serum, water-soluble, amenable to cell culture experiments, and inhibit both SIRT2 deacetylation and demyristoylation. Compared to the current landscape of SIRT2 inhibitors, this is a unique ensemble of features built into a single compound. We expect the developed chemotypes to find broad application in the interrogation of SIRT2 functions in both healthy and diseased cells, and to provide a foundation for the development of future therapeutics.

biochemistry↗