Molecular cloning and functional characterization of a glucose transporter (CsGLUT) in Clonorchis sinensis

Abstract

A complementary DNA (cDNA) encoding a glucose transporter of Clonorchis sinensis (CsGLUT) was isolated from the adult C. sinensis cDNA library. The open reading frame of CsGLUT cDNA consists of 1653 base pairs that encode a 550-amino acid residue protein. Hydropathy analysis suggested that CsGLUT possess 12 putative membrane-spanning domains. The Northern blot analysis result using poly(A)(+)RNA showed a strong band at ~2.1 kb for CsGLUT. When expressed in Xenopus oocytes, CsGLUT mediated the transport of radiolabeled deoxy-D-glucose in a time-dependent but sodium-independent manner. Concentration-dependency results showed saturable kinetics and followed the Michaelis-Menten equation. Nonlinear regression analyses yielded a Km value of 588.5 ± 53.0 μM and a Vmax value of 1500.0 ± 67.5 pmol/oocyte/30 min for [1,2-(3)H]2-deoxy-D-glucose. No trans-uptakes of bile acid (taurocholic acid), amino acids (tryptophan and arginine), or p-aminohippuric acid were observed. CsGLUT-mediated transport of deoxyglucose was significantly and concentration-dependently inhibited by radio-unlabeled deoxyglucose and D-glucose. 3-O-Methylglucose at 10 and 100 μM inhibited deoxyglucose uptake by ~50 % without concentration dependence. No inhibitory effects by galactose, mannose, and fructose were observed. This work may contribute to the molecular biological study of carbohydrate metabolism and new drug development of C. sinensis.

In silico analyses of protein glycosylating genes in the helminth Fasciola hepatica (liver fluke) predict protein-linked glycan simplicity and reveal temporally-dynamic expression profiles

“…mansoni ) and cestodes ( Taenia spp.) 30 – 40 , with the four S . mansoni transporters (SGTP1-4) being the most intensively studied 30 , 32 , 37 .…”

“…mansoni SGTP1 and SGTP4, and the C . sinensis glucose transporter CsGLUT 40 . Further transporters appeared within our phylogeny, one in in Class III (BN1106_s373B000291), and one residing between Classes II and III (D915_03610).…”

Amino acids serve as an important energy source for adult flukes of Clonorchis sinensis

“…Trematodes have the ability to import glucose and amino acids directly across their tegument facilitated by glucose and amino acid transporters [34,[53][54][55]. Thus, exogenous glucose and amino acids in DMEM could be absorbed and catabolized by C. sinensis adults, which is coupled to ATP production for extending the survival time of adult flukes [12,18] (Fig 1B and S3 Table).…”