Lecture
LIC Guest Lecture: Controlling biological systems: From nanopore-forming toxins to a chemical-genetic system to map ZDHHC-specific S-acylation
- Dr. Jana Volaric (Imperial College London)
- Date
- Wednesday 10 July 2024
- Time
- Location
-
Gorlaeus Building
Einsteinweg 55
2333 CC Leiden - Room
- CM.3.23
Abstract
Manipulating the activity of biological systems provides ample opportunities to investigate their mode of action thus leading to a better understanding of the underlaying mechanism and for developing novel therapeutics. During my PhD within the Feringa group (RuG) and my postdoc at the Tate group (Imperial) I have worked on controlling biological systems with light and by implementing a chemical-genetic system.
Part 1
Molecular photoswitches change their shape and properties upon irradiation with light, and thus can be utilized as a powerful tool to enable reversible control of the studied system with spatio-temporal resolution. Azobenzene photoswitches were used to harness the cell-lysing activity of a nanopore-forming toxin Fragaceatoxin C (FraC). FraC binds to the surface of sphingomyelin-rich cells, assembles into pores puncturing holes into the cell membrane resulting in cell death. We found several constructs in which the affinity of the toxin for biological membranes could be activated or deactivated by irradiation, enabling reversible photocontrol of pore formation. The photoswitch design was further optimized to enable use of only visible light.
Part 2
Protein lipidation plays a pivotal role in protein stability, conformation, localisation, secretion and protein-protein interactions. Protein S‐acylation is a post-translational modification where long-chain fatty acids are reversibly transferred onto cysteine residues through a thioester linkage, a process mediated by 23 S‐acyltransferases of the ZDHHC enzyme family and reversed by S‐acyl protein thioesterases. Over 3,000 cysteine residues across ca. 12% of the human proteome are lipidated by the ZDHHC enzyme family, and therefore S-acylation is implicated in numerous metabolic, neurological and immune diseases, as well as in different types of cancer. The Tate group has developed a chemical genetic system which allows substrate protein labelling to be channelled through a single specific ZDHHC in intact cells. The design involves a “bump-and-hole” steric complementation approach where a specific ZDHHC is genetically modified to contain a cavity within the active site and matched to a lipid probe with a “bump” group which fits the cavity. The “bumped” probe is loaded specifically on the “hole” mutant ZDHHC but is sterically blocked from entering the cavity of any wild type ZDHHC. This design allows dissection of specific substrates modified by a single ZDHHC, an unprecedented study which offers a unique opportunity to identify new substrates and study specific ZDHHC members.
Biography
Jana Volaric completed her BSc in chemistry at University of Zagreb (Croatia) and moved to the Netherlands to finish her MSc in organic chemistry at the University of Groningen where she joined the Feringa group to work on molecular motor-based catalysts. After a short internship in the lab of prof Hidde Ploegh (MIT) working on influenza A virus, Jana joined the photopharmacology team in Groningen for her PhD under the guidance of prof. Ben Feringa and prof. Wiktor Szymanski where she synthesized water-soluble photoswitches and applied them to control biological systems. Currently she is a Rubicon fellow in the group of Ed Tate where she is working on studying protein lipidation with a chemical-genetic approach and light responsive molecules.