BASF Lectureship in Chemical Sciences: Studies of the Assembly of the Thioheptose Core of Albomycins

Seminar | November 12 | 11 a.m.-12 p.m. | 120 Latimer Hall

 Ben Liu, Department of Chemistry, University of Texas at Austin

 College of Chemistry

Sulfur is an essential element for life and is found in all living systems. Yet, how the sulfur is incorporated in many sulfur-containing secondary metabolites remains poorly understood. Albomycin δ2 is an unusual naturally occurring nucleoside that possesses a sulfur-containing furanose, which is essential for its potent antibiotic activity against clinically important pathogens. The structure of albomycin is characterized by a thioheptose core with atypical stereochemistry including a D-xylofuranose ring modified with a D-amino acid moiety. During the biosynthesis of albomycin δ2, a pyridoxal 5′-phosphate (PLP)-dependent transaldolase catalyzes a threo-selective aldol-type reaction to generate the thioheptose core with a D-ribofuranose ring modified with an L-amino acid moiety. The D-amino acid configuration is then introduced by another PLP-dependent epimerase. Furthermore, the D-ribo to D-xylo conversion of the thiofuranose ring is mediated by a radical S-adenosyl-L-methionine (SAM) enzyme. Recently, we have identified another radical SAM enzyme that catalyzes construction of the thiofuranose ring via sulfur incorporation into cytidine 5′-diphosphate. These results will be presented in the lecture.


 Ben Liu CV