Title: Purification and characterization of phosphonoglycans from glycomyces sp. NRRL B-16210 and stackebrandtia nassauensis NRRL B-16338 Authors
|Yu, Xiaomin -|
|Metcalf, William -|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 20, 2012
Publication Date: June 20, 2012
Citation: Yu, X., Price, N.P., Metcalf, W.W. 2012. Purification and characterization of phosphonoglycans from glycomyces sp. NRRL B-16210 and stackebrandtia nassauensis NRRL B-16338 [abstract]. American Society for Microbiology. Technical Abstract: Phosphonates, compounds with direct C-P bonds, consist of a group of chemically diverse natural products, which play important roles in the global environment. We identified phosphonate biosynthetic gene clusters from two actinomycete strains, Glycomyces sp. NRRL B-16210 and Stackebrandtia nassauensis NRRL B-16338, by screening for the PEP mutase gene, which is required for the biosynthesis of most phosphonates. Subsequent examination of the two strains by 31P NMR led to the detection of phosphonate-containing exopolysaccharides (EPS) (also known as phosphonoglycans). The phosphonoglycans were purified by sequential organic solvent extractions, methanol precipitation and size-exclusion ultra-filtration. The phosphonate moiety in both phosphonoglycans was shown to be 2-hydroxyethylphosphonate (2-HEP) by a series of 1D and 2D NMR experiments. NMR and GC-MS analysis indicated that the EPS from Glycomyces sp. NRRL B-16210 has a mass of 40-50 kDa and is composed of galactose, xylose, N-acetylglucosamine and five distinct partially O-methylated galactose residues, with galactose being the largest component (70.7%). Similarly, the EPS from S. nassauensis NRRL B-16338 was shown to comprise glucose, galactose, xylose, and four partially O-methylated galactose residues, with glucose being the most abundant sugar monomer (73.2%). Heterologous expression of the two putative phosphonoglycan biosynthetic gene clusters in Streptomyces lividans TK24 only yielded 2-HEP with no sugars linked. The function of these phosphonoglycans still remains elusive. Further chemical and genetic characterizations will shed light on their structures and biosynthesis.