The mature cyst of Acanthamoeba is highly resistant to various antibiotics and therapeutic agents. Cyst wall of Acanthamoeba are composed of cellulose, acid-resistant proteins, lipids, and unidentified materials. Because cellulose is one of the primary components of the inner cyst wall, cellulose synthesis is essential to the process of cyst formation in Acanthamoeba. In this study, we hypothesized the key and short-step process in synthesis of cellulose from glycogen in encysting Acanthamoeba castellanii, and confirmed it by comparing the expression pattern of enzymes involving glycogenolysis and cellulose synthesis. The genes of 3 enzymes, glycogen phosphorylase, UDP-glucose pyrophosphorylase, and cellulose synthase, which are involved in the cellulose synthesis, were expressed high at the 1st and 2nd day of encystation. However, the phosphoglucomutase that facilitates the interconversion of glucose 1-phosphate and glucose 6-phosphate expressed low during encystation. This report identified the short-cut pathway of cellulose synthesis required for construction of the cyst wall during the encystation process in Acanthamoeba. This study provides important information to understand cyst wall formation in encysting Acanthamoeba.
Acanthamoeba castellanii/*enzymology/genetics/growth & development ; Amebiasis/*parasitology ; Cell Wall/*metabolism ; Cellulose/*biosynthesis/genetics ; Glucosyltransferases/genetics/metabolism ; Glycogen Phosphorylase/genetics/metabolism ; Protozoan Proteins/genetics/*metabolism ; UTP-Glucose-1-Phosphate Uridylyltransferase/genetics/metabolism

Acanthamoeba cysts are resistant to unfavorable physiological conditions and various disinfectants. Acanthamoeba cysts have 2 walls containing various sugar moieties, and in particular, one third of the inner wall is composed of cellulose. In this study, it has been shown that down-regulation of cellulose synthase by small interfering RNA (siRNA) significantly inhibits the formation of mature Acanthamoeba castellanii cysts. Calcofluor white staining and transmission electron microscopy revealed that siRNA transfected amoeba failed to form an inner wall during encystation and thus are likely to be more vulnerable. In addition, the expression of xylose isomerase, which is involved in cyst wall formation, was not altered in cellulose synthase down-regulated amoeba, indicating that cellulose synthase is a crucial factor for inner wall formation by Acanthamoeba during encystation.
Acanthamoeba castellanii/*enzymology/genetics/metabolism ; Aldose-Ketose Isomerases/*biosynthesis ; Amebiasis/*pathology ; Benzenesulfonates ; Cell Wall/chemistry/genetics/*metabolism ; Cellulose/biosynthesis ; Down-Regulation ; Encephalitis/parasitology ; Glucosyltransferases/*biosynthesis/genetics ; Keratitis/parasitology ; Microscopy, Electron, Transmission ; RNA Interference ; RNA, Small Interfering