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Christoph Albermann

Publications and source records attributed to Christoph Albermann.

8 recordsLinked to original sources
PubMed2006

The in vitro characterization of the iterative avermectin glycosyltransferase AveBI reveals reaction reversibility and sugar nucleotide flexibility.

The glycosyltransferase AveBI, which is involved in the biosynthesis of the macrolide antihelmintic avermectin (AVM), was characterized in vitro. AveBI was confirmed to catalyze two separate iterative additions of l-oleandrose, and the reversibility of AveBI-catalyzed reaction was also demonstrated. Investigation of sugar nucleotide specificity revealed 10 unique sugar nucleotide substrates which, in combination with five distinct aglycones, led to the production of 50 differentially glycosylated AVM variants.

Catalysis↗
PubMed2006

Exploiting the reversibility of natural product glycosyltransferase-catalyzed reactions.

Glycosyltransferases (GTs), an essential class of ubiquitous enzymes, are generally perceived as unidirectional catalysts. In contrast, we report that four glycosyltransferases from two distinct natural product biosynthetic pathways-calicheamicin and vancomycin-readily catalyze reversible reactions, allowing sugars and aglycons to be exchanged with ease. As proof of the broader applicability of these new reactions, more than 70 differentially glycosylated calicheamicin and vancomycin variants are reported. This study suggests the reversibility of GT-catalyzed reactions may be general and useful for generating exotic nucleotide sugars, establishing in vitro GT activity in complex systems, and enhancing natural product diversity.

Aminoglycosides↗
PubMed2006

RebG- and RebM-catalyzed indolocarbazole diversification.

Rebeccamycin and staurosporine represent two broad classes of indolocarbazole glycoside natural products with antitumor properties. Based upon previous sequence annotation and in vivo studies, rebG encodes for the rebeccamycin N-glucosyltransferase, and rebM for the requisite 4'-O-methyltransferase. In the current study, an efficient in vivo biotransformation system for RebG was established in both Streptomyces lividans and Escherichia coli. Bioconversion experiments revealed RebG to glucosylate a set of indolocarbazole surrogates, the products of which could be further modified by in vitro RebM-catalyzed 4'-O-methylation. Both RebG and RebM displayed substrate promiscuity, and evidence for a remarkable lack of RebG regioselectivity in the presence of asymmetric substrates is also provided. In the context of the created indolocarbazole analogues, cytotoxicity assays also highlight the importance of 4'-O-methylation for their biological activity.

Bacterial Proteins↗
PubMed2005

Diversifying vancomycin via chemoenzymatic strategies.

[reaction: see text] The rapid diversification of glycopeptides via glycorandomization reveals that significantly diverse substitutions are tolerated and suggests there may be a synergistic benefit to the construction of mechanistically related natural product core scaffold fusions. This work also further highlights the utility of chemoenzymatic approaches to diversify complex natural product architectures.

Combinatorial Chemistry Techniques↗
PubMed2003

Antibiotic optimization via in vitro glycorandomization.

In nature, the attachment of sugars to small molecules is often used to mediate targeting, mechanism of action and/or pharmacology. As an alternative to pathway engineering or total synthesis, we report a useful method, in vitro glycorandomization (IVG), to diversify the glycosylation patterns of complex natural products. We have used flexible glycosyltransferases on nucleotide diphosphosugar (NDP-sugar) libraries to generate glycorandomized natural products and then applied chemoselective ligation to produce monoglycosylated vancomycins that rival vancomycin.

Anti-Bacterial Agents↗
PubMed2003

Substrate specificity of NovM: implications for novobiocin biosynthesis and glycorandomization.

[reaction: see text] In an effort to expand the scope of natural product in vitro glycorandomization (IVG), the substrate specificity of NovM was investigated. A test of four aglycon analogues and over 40 nucleotide sugars revealed NovM has a surprisingly stringent substrate specificity and provided only three new "unnatural" natural products. On the basis of the determined substrate specificity, an alternative to the sugar nucleotide biosynthetic dogma and a cautionary note for the general applicability of IVG are introduced.

Anti-Bacterial Agents↗