Year of Publication

2013

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Pharmacy

Department

Pharmaceutical Sciences

First Advisor

Dr. Steven Van Lanen

Abstract

Several lipopeptidyl nucleoside antibiotics that inhibit bacterial translocase I (MraY) involved in peptidoglycan cell wall biosynthesis contain an aminoribosyl moiety, an unusual sugar appendage in natural products. A-90289 and muraminomicin are the two representative antibiotics that belong to this family. Bioinformatic analysis of the biosynthetic A-90289 gene clusters revealed that five enzymes are likely involved in the assembly and attachment of the aminoribosyl unit. These enzymes of A-90289 are functionally assigned by in vitro characterization. The results reveal a unique ribosylation pathway that highlighted by uridine-5′-monophosphate as the source of the sugar, a phosphorylase strategy to generate a sugar-1-phosphate, and a primary amine-requiring nucleotidylyltransferase that generates the NDP-sugar donor. Muraminomicin, which has a structure similar to A-90289, holds the distinction in that both ribose units are 2-deoxy sugars. The biosynthetic gene cluster of muraminomicin has been identified, cloned and sequenced, and bioinformatic analysis revealed a minimum of 24 open reading frames putatively involved in the biosynthesis, resistance, and regulation of muraminomicin. Similar to the A-90289 pathway, fives enzymes are still likely involved in the assembly of the 2,5-dideoxy-5-aminoribose saccharide unit, and two are now functionally assigned and characterized: Mra20, a 5′-amino-2′,5′-dideoxyuridine phosphorylase and Mra23, a UTP:5-amino-2,5-dideoxy-α-D-ribose-1-phosphate uridylyltransferase. The cumulative results are consistent with the incorporation of the ribosyl appendage of muraminomicin via the archetypical sugar biosynthetic pathway that parallels A-90289 biosynthesis