| Title: | Identification of a dTDP-rhamnose biosynthetic pathway that oscillates with the molting cycle in Caenorhabditis elegans |
| Author(s): | Feng L; Shou Q; Butcher RA; |
| Address: | "Department of Chemistry, University of Florida, Gainesville, FL 32611, U.S.A. Department of Chemistry, University of Florida, Gainesville, FL 32611, U.S.A. butcher@chem.ufl.edu" |
| ISSN/ISBN: | 1470-8728 (Electronic) 0264-6021 (Print) 0264-6021 (Linking) |
| Abstract: | "L-Rhamnose is a common component of cell-wall polysaccharides, glycoproteins and some natural products in bacteria and plants, but is rare in fungi and animals. In the present study, we identify and characterize a biosynthetic pathway for dTDP-rhamnose in Caenorhabditis elegans that is highly conserved across nematode species. We show that RML-1 activates glucose 1-phosphate (Glc-1-P) in the presence of either dTTP or UTP to yield dTDP-glucose or UDP-glucose, respectively. RML-2 is a dTDP-glucose 4,6-dehydratase, converting dTDP-glucose into dTDP-4-keto-6-deoxyglucose. Using mass spectrometry and NMR spectroscopy, we demonstrate that coincubation of dTDP-4-keto-6-deoxyglucose with RML-3 (3,5-epimerase) and RML-4 (4-keto-reductase) produces dTDP-rhamnose. RML-4 could only be expressed and purified in an active form through co-expression with a co-regulated protein, RML-5, which forms a complex with RML-4. Analysis of the sugar nucleotide pool in C. elegans established the presence of dTDP-rhamnose in vivo Targeting the expression of the rhamnose biosynthetic genes by RNAi resulted in significant reductions in dTDP-rhamnose, but had no effect on the biosynthesis of a closely related sugar, ascarylose, found in the ascaroside pheromones. Therefore, the rhamnose and ascarylose biosynthetic pathways are distinct. We also show that transcriptional reporters for the rhamnose biosynthetic genes are expressed highly in the embryo, in the hypodermis during molting cycles and in the hypodermal seam cells specifically before the molt to the stress-resistant dauer larval stage. These expression patterns suggest that rhamnose biosynthesis may play an important role in hypodermal development or the production of the cuticle or surface coat during molting" |
| Keywords: | "Animals Biosynthetic Pathways/physiology Caenorhabditis elegans/*metabolism Caenorhabditis elegans Proteins/genetics/metabolism Chromatography, High Pressure Liquid Deoxyglucose/analogs & derivatives/metabolism Glucose/analogs & derivatives/metabolism Glu;" |
| Notes: | "MedlineFeng, Likui Shou, Qingyao Butcher, Rebecca A eng P40 OD010440/OD/NIH HHS/ Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't England 2016/03/25 Biochem J. 2016 Jun 1; 473(11):1507-21. doi: 10.1042/BCJ20160142. Epub 2016 Mar 23" |
