C4-monomethylsterol ß-glucoside and its synthase in Aurantiochytrium limacinum mh0186.

Thraustochytrids, unicellular marine protists, synthesize polyunsaturated fatty acids (PUFAs) and PUFA-containing phospholipids; however, little is known about their glycolipids and their associated metabolism. Here, we report two glycolipids (GL-A, B) and their synthases in Aurantiochytrium limacinum mh0186. Two glycolipids were purified from A. limacinum mh0186, and they were determined by gas chromatography, mass spectrometry and 2D nuclear magnetic resonance to be 3-O-ß-D-glucopyranosyl-stigmasta-5,7,22-triene (GL-A) and 3-O-ß-D-glucopyranosyl-4α-methyl-stigmasta-7,22-diene (GL-B), both of which are sterol ß-glucosides (ß-SGs); the structure of GL-B has not been reported thus far. Seven candidate genes responsible for the synthesis of these ß-SGs were extracted from the draft genome database of A. limacinum using the yeast sterol ß-glucosyltransferase (SGT; EC 2.4.1.173) sequence as a query. Expression analysis using Saccharomyces cerevisiae revealed that two gene products (AlSGT-1 and 2) catalyze the transfer of glucose from uridine diphosphate (UDP)-glucose to sterols, generating sterylglucosides (SGs). Compared to AlSGT-1, AlSGT-2 exhibited wide specificity for sterols and used C4-monomethylsterol to synthesize GL-B. The disruption of alsgt-2 but not alsgt-1 in strain mh0186 resulted in a decrease in the total SG and an almost complete loss of GL-B, indicating that AlSGT-2 is responsible for the synthesis of ß-SGs in A. limacinum mh0186, especially GL-B, which possesses a unique sterol structure.

Clinical Evaluation of the Immunochromatographic System Using Silver Amplification for the Rapid Detection of Mycoplasma pneumoniae.

Mycoplasma pneumoniae infection is conventionally diagnosed using serum antibody testing, microbial culture, and genetic testing. Recently, immunochromatography-based rapid mycoplasma antigen test kits have been developed and commercialised for rapid diagnosis of M. pneumoniae infection. However, as these kits do not provide sufficient sensitivity and specificity, a rapid test kit with improved accuracy is desired. The present prospective study evaluated a rapid M. pneumoniae diagnostic system utilizing a newly developed silver amplification immunochromatography (SAI) system. We performed dilution sensitivity test and the prospective clinical study evaluating the SAI system. The subjects of the clinical study included both children and adults. All patients suspected to have mycoplasma pneumonia (169 patients) were sequentially enrolled. Twelve patients did not agree to participate and 157 patients were enrolled in the study. The results demonstrate excellent performance of this system with 90.4% sensitivity and 100.0% specificity compared with real-time polymerase chain reaction. When compared with loop-mediated isothermal amplification (LAMP) methods, the results also demonstrate a high performance of this system with 93.0% sensitivity and 100.0% specificity. The SAI system uses a dedicated device for automatic analysis and reading, making it highly objective, and requires less human power, supporting its usefulness in clinical settings.

Ergosteryl-ß-glucosidase (Egh1) involved in sterylglucoside catabolism and vacuole formation in Saccharomyces cerevisiae.

Sterylglucosides (SGs) are composed of a glucose and sterol derivatives, and are distributed in fungi, plants and mammals. We recently identified EGCrP1 and EGCrP2 (endoglycoceramidase-related proteins 1 and 2) as a ß-glucocerebrosidase and steryl-ß-glucosidase, respectively, in Cryptococcus neoformans. We herein describe an EGCrP2 homologue (Egh1; ORF name, Yir007w) involved in SG catabolism in Saccharomyces cerevisiae. The purified recombinant Egh1 hydrolyzed various ß-glucosides including ergosteryl ß-glucoside (EG), cholesteryl ß-glucoside, sitosteryl ß-glucoside, para-nitrophenyl ß-glucoside, 4-methylumberifellyl ß-glucoside and glucosylceramide. The disruption of EGH1 in S. cerevisiae BY4741 (egh1Δ) resulted in the accumulation of EG and fragmentation of vacuoles. The expression of EGH1 in egh1Δ (revertant) reduced the accumulation of EG, and restored the morphology of vacuoles. The accumulation of EG was not detected in EGH1 and UGT51(ATG26) double-disrupted mutants (ugt51Δegh1Δ), indicating that EG was synthesized by Ugt51(Atg26) and degraded by Egh1 in vivo. These results clearly demonstrated that Egh1 is an ergosteryl-ß-glucosidase that is functionally involved in the EG catabolic pathway and vacuole formation in S. cerevisiae.