Characterization of the Cellular Uptake and Metabolic Conversion of Acetylated N-Acetylmannosamine (ManNAc) Analogues to Sialic Acids

Mark B. Jones, Howard Teng, Jun Kyu Rhee, Nicholas Lahar, Gautam Baskaran, Kevin J. Yarema

Research output: Contribution to journalArticlepeer-review

Abstract

"Sialic acid engineering" refers to the strategy where cell surface carbohydrates are modified by the biosynthetic incorporation of metabolic intermediates, such as non-natural N-acetylmannosamine (ManNAc) analogues, into cellular glycoconjugates. While this technology has promising research, biomedical, and biotechnological applications due to its ability to endow the cell surface with novel physical and chemical properties, its adoption on a large scale is hindered by the inefficient metabolic utilization of ManNAc analogues. We are addressing this limitation by developing acetylated ManNAc analogues for general use in sialic acid engineering applications. In this paper, the metabolic flux of these "second-generation" compounds into a cell, and, subsequently, into the target sialic acid biosynthetic pathway is characterized in detail. We show that acetylated ManNAc analogues are metabolized up to 900-fold more efficiently than their natural counterparts. The acetylated compounds, however, decrease cell viability under certain culture conditions. To determine if these toxic side effects can be avoided, we developed an assay to measure the cellular uptake of acetylated ManNAc from the culture medium and its subsequent flux into sialic acid biosynthetic pathway. This assay shows that the majority (> 80%) of acetylated ManNAc is stored in a cellular "reservoir" capable of safely sequestering this analogue. These results provide conditions that, from a practical perspective, enable the acetylated analogues to be used safely and efficaciously and therefore offer a general strategy to facilitate metabolic substrate-based carbohydrate engineering efforts. In addition, these results provide fundamental new insights into the metabolic processing of non-natural monosaccharides.

Original languageEnglish (US)
Pages (from-to)394-405
Number of pages12
JournalBiotechnology and bioengineering
Volume85
Issue number4
DOIs
StatePublished - Feb 20 2004

Keywords

  • Acetylated N-acetylmannosamine analogues
  • Glycosylation
  • Metabolic and cell engineering
  • Metabolic flux analysis
  • Sialic acid engineering

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology

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