Structural and Mechanistic Studies of Strained Ring Forming Enzymes and Bifunctional Systems in Terpene Biosynthesis Matthew N Gaynes

Format:

Book

Thesis/Dissertation

Author/Creator:

Gaynes, Matthew N., author.

Contributor:

University of Pennsylvania. Chemistry., degree granting institution.

Language:

English

Subjects (All):

0485.

0487.

0490.

0786.

Local Subjects:

0485.

0487.

0490.

0786.

Physical Description:

1 electronic resource (276 pages)

Contained In:

Dissertations Abstracts International 87-07B

Place of Publication:

Ann Arbor : ProQuest Dissertations and Theses, 2025

Language Note:

English

Summary:

Terpenes comprise the largest class of natural products and exhibit impressive utility which spans diverse applications, including roles as bioactive molecules, fragrances in cosmetics, and environmentally impactful next-generation biofuels. Terpene biosynthesis is a striking example of nature's synthetic capability, featuring some of the most complex enzymatic chemistry, as carbocation driven cyclization cascades alter the bonding, hybridization, and stereochemistry of on average more than half of the substrate carbon atoms. Elucidating how such chemistry is achieved requires detailed insights into the structure-function relationship of the involved biosynthetic enzymes. Terpene production begins with the prenyltransferase, which extend simple C5 precursors into longer isoprenoid diphosphates. These are then utilized by terpene synthases of two mechanistic and structural classes. Class I synthases require metal binding to initiate pyrophosphate ionization, and class II synthases contain a catalytic acid which protonates the terminal double bond of the substrate establishing distinct methods of carbocation generation. Both classes facilitate cyclization steps resulting in the production of intricate polycyclic molecules with defined stereo- and regio- chemistry.This work presents new findings on two class I cyclases and a bifunctional terpene synthase system which has both a prenyltransferase and class II cyclase. Sabinene synthase, a plant monoterpene cyclase, and avermitilol synthase, a bacterial sesquiterpene cyclase, are both class I enzymes that generate products with strained ring systems. This work reports the first crystal structures of cyclases responsible for producing these strained-ring products, accompanied by biochemical studies that highlight the ability of both enzymes to utilize a broad range of divalent metal ions. Active site mutagenesis reveals critical features of enzyme function, including a residue in sabinene synthase that modulates activity towards α-pinene production and a mutation in avermitilol synthase that alters hydroxylation outcomes. In addition, we report structural insights into bifunctional copalyl diphosphate synthase from two Penicillium species, including separately solved structures of the prenyltransferase and class II cyclase domains, together with experiments demonstrating that substrate channeling operates in systems containing a class II cyclase

Notes:

Advisors: Christianson, David W. Committee members: Marmorstein, Ronen; McCallum, Monica E.; Baumgart, Tobias

Source: Dissertations Abstracts International, Volume: 87-07, Section: B.

Ph.D. University of Pennsylvania 2025

Vendor supplied data

Local Notes:

School code: 0175

ISBN:

9798276007175

Access Restriction:

Restricted for use by site license