Functional characterization of Helicobacter pylori 26695 sedoheptulose 7-phosphate isomerase encoded by hp0857 and its association with lipopolysaccharide biosynthesis and adhesion.

Helicobacter pylori is a notorious human pathogen and the appearance of antibiotic resistance of this bacterium has posed a serious threat to human health. Lipopolysaccharide (LPS) is a key virulence factor and plays important roles in pathogenesis of H. pylori infection. Sedoheptulose 7-phosphate isomerase (GmhA), as an enzyme participating in the first step of heptose biosynthesis, is indispensable for the formation of inner core oligosaccharide of LPS. In this study, we cloned one putative gmhA ortholog, hp0857, from H. pylori 26695 and overexpressed it in Eschericha coli. Based on the results of molecular weight determination, the recombinant HP0857 is likely a homodimer. Analysis of enzymatic kinetic properties of this protein confirmed that hp0857 is indeed encoded a phosphoheptose isomerase which can utilize sedoheptulose 7-phosphate as the substrate in the ADP-L-glycero-D-manno-heptose (ADP- L,D-Hep) biosynthesis pathway. We also generated an HP0857 knockout mutant and explored its phenotypic changes. This mutant exhibited a decreased growth rate and displayed a "deep rough" type of LPS structure. In addition, it also had a slight decrease in its motility and was more susceptible to hydrophobic antibiotic novobiocin and detergents Triton X-100 and SDS. Furthermore, the adhesive capacity of the HP0857 knockout mutant to AGS cells was reduced significantly, and most of the infected cells didn't show a classic hummingbird phenotype. However, complementation of the HP0857 knockout mutation restored most of these phenotypic changes. In conclusion, we demonstrated that HP0857 protein is essential for inner core biosynthesis of H. pylori LPS and is a potential target for developing new antimicrobial agents against H. pylori infection.

Construction and Validation of a Perceived Physical Literacy Instrument for Physical Education Teachers.

The purpose of this study was to construct and validate a "Perceived Physical Literacy Instrument" (PPLI) for physical education teachers. Based on literature review and focus group interviews, an 18-item instrument was developed for the initial tests. This self-report measure, using a 5-point Likert scale, formed the PPLI and was administered to 336 physical education teachers in Hong Kong. The sample was randomly split, and exploratory and confirmatory factor analyses resulted in a 9-item, 3-factor scale. Exploratory factor analysis (EFA) item loadings ranged from 0.69 to 0.87, and Cronbach's alpha ranged from 0.73 to 0.76. Confirmatory factor analysis (CFA) showed that the construct demonstrated good fit to the model. The PPLI thus appeared to be reliable and valid to measure the perceived physical literacy of physical education teachers. It is argued that the instrument can be used for both research and applied purposes and potential uses for the instrument in physical education, medical and health settings are discussed.