OBJECTIVEFungal keratitis (FK) is a vision-threatening infection, whose treatment requires more effective and safer anti-fungal agent exploitation urgently. With this aim, we focused on the effect of an extracellular polysaccharide on fungal adhesion to human corneal epithelial cells.

METHODSWe performed the cytotoxicity assays of the extracellular polysaccharide EPS-II from an antarctic bacterium Pseudoaltermonas and evaluated its inhibitory effect on Candida albicans cells' adherence to human corneal epithelial cells (HCECs).

RESULTSEPS-II, which displayed minor cytotoxicity but also promoted proliferation of HCECs, could inhibit the adherence of yeast cells to HCECs in a dose-dependent manner. EPS-II could also suppress the subsequent PI3K/AKT signaling pathway, and thereby decrease the expression of early inflammatory cytokines.

CONCLUSIONSExtracellular polysaccharide EPS-II was suggested as a new natural agent for attenuating FK.

Blotting, Western ; Candida ; drug effects ; physiology ; Cell Adhesion ; drug effects ; Cornea ; microbiology ; Humans ; Phosphorylation ; Polysaccharides, Bacterial ; pharmacology ; Proto-Oncogene Proteins c-akt ; metabolism ; Pseudoalteromonas ; metabolism

A bacteria strain DY3 with high endoglucanse activity was isolated from deep sea sediment sample ES0109. The 16S rDNA sequence of DY3 exhibits identity of 99% with those of the same genus bacteria Pseudoalteromonas citrea and Pseudoalteromonas elyakovii . The celX gene of DY3 obtained by PCR method is 1479bp in length and encodes a protein of 492 amino acids. The protein encoded by celX gene exhibits 95% sequence identity with endoglucanase CelG from Pseudoalteromonas haloplanktis. There are two modules in the deduced amino acids sequence, a catalytic domain of glycosyl hydrolases family 5 at the N terminal and a carbohydrate binding domain at the C terminal which was linked to catalytic domain by a short linker. The optimal temperature of CelX is 40 degrees C and the optimal pH was between 6 and 7.
Amino Acid Sequence ; Bacterial Proteins ; genetics ; Cellulase ; genetics ; Cloning, Molecular ; Gene Expression Regulation, Enzymologic ; Molecular Sequence Data ; Pseudoalteromonas ; enzymology ; genetics ; Sequence Alignment