Oct 31
Chemistry Department Seminar: Tamra Lahom
NIH postdoctoral fellow at UPenn & Assistant Professor of Chemistry at Carleton College
"It’s Electric! Characterization of the Metal Centers Behind C(sp3)-C(sp3) Coupling"
Archaea can thrive under extreme environmental conditions due to several unique lipid membrane features. Instead of a lipid bilayer, archaea often exhibit a monolayer consisting of membrane-spanning lipids known as glycerol dibiphytanyl glycerol tetraether (GDGT). In Methanocaldococcus jannaschii (MJ), the phytanyl chains of a diether GDGT precursor, diether archaeal lipid, are tethered via a C–C bond to form a biphytanyl chain. In MJ, biphytanyl chain generation can be an intermolecular C(sp3)-C(sp3) bond formation resulting in GDGT lipids or intramolecular C(sp3)-C(sp3) bond formation resulting in macrocyclic diether lipids. In 2022, our lab discovered the enzymatic “missing link” responsible for biphytanyl chain formation in archaeal lipid biosynthesis, radical SAM, Tetraether Synthase (Tes). While our lab proposed a mechanism, it excluded the two remaining metal centers in Tes. This talk details the electrochemical and enzymatic activity characterization of Tes. Electrochemical characterization of WT Tes and its variants coupled to biochemical characterization hints that the role of one of the metal centers excluded from the original mechanism is one of critical electron shuttling out of the system. Our results do not support the formation of a 2+/3+ “HiPP” cluster for either the N-Term or C-term cluster, providing further support for a C-S intermediate.
**This seminar counts towards the chemistry major seminar attendance requirement.
from Chemistry