Abstract

Cyanobacteria are photosynthetic microorganisms that have been around for billions of years. They play an important role in balancing carbon and nitrogen in the environment. Because they can live in a wide range of habitats, cyanobacteria have evolved to produce unique, bioactive compounds.

Tolyporphin A is an unusual tetrapyrrole secondary metabolite containing pendant deoxysugars and unsubstituted pyrrole β sites. We describe the biosynthesis of the tolyporphin aglycon core.¹ HemF1 catalyzes the oxidative decarboxylation of two propionate side chains of coproporphyrinogen III, an intermediate in heme biosynthesis. HemF2 then processes the two remaining propionate groups to generate a tetravinyl intermediate. All four vinyl groups from the macrocycle are truncated by TolI via repeated C−C bond cleavages to generate the unsubstituted pyrrole β sites of tolyporphins. This study illustrates how the unprecedented C−C bond cleavage reactions branch from canonical heme biosynthesis to produce tolyporphins. Other cyanobacterial natural products will be also discussed in the talk.²

Biography

Richiro 开云体育 received both Bachelor’s and Master’s degrees in Chemistry from Nagoya University. During his master study, he worked in the laboratory of Prof. Ryoji Noyori on the development of transition metal-based catalysts. He worked with Prof. Hung-wen Liu and completed his Ph.D. in Chemistry at The University of Texas at Austin in 2019. His graduate research focused on biosynthesis of thiosugar-containing natural products. Currently, he is an assistant professor at the Graduate School of Pharmaceutical Sciences, The University of Tokyo and work with Prof. Ikuro Abe. His primary research interests include studying the mechanisms of metalloenzymes.