Study on Fapl glycosylation and maturation regulating by ORF3 coded by fap1-orf4 gene locus of Streptococcus parasanguis

Objective: To study whether 0RF3 coded by fapl-orf4 gene locus of Streptococcus parasanguis is involved in the regulation of Fapl glycosylation and maturation and to investigate whether 0RF3 influences Streptococcus parasanguis adhesion. Methods: A gene replacement strategy was adapted to construct orf3 alleic replace mutant of Streptococcus parasanguis. Complementation assay and Western blot were used to test Fapl expression levels. Whole saliva-coated hydroxyapatite (SHA) adhesion assay was adapted to determine Streptococcus parasanguis adhension. Results: (1) Non-polar was found in strain VT1774, the orf3 alleic replace mutant of Streptococcus parasanguis. (2) Western blot showed that mature Fapl (M _r about 220 × 10 ³) disappeared and were substituted with high molecular weight Fapl (M _r about 470 × 10 ³) in strain VT1774, furthermore, complementation assay showed VT1775, the complementation strain of VT1774, restored mature Fapl expression. (3) The binding ability reduced significantly in strain VT1774. Conclusion: ORF3 coded by fapl-orf4 gene locus was required for Fapl glycosylation and maturation in Streptococcus parasanguis. orft alleic replacment resulted in Fapl glycosylation and mature disorder and decreasing of adhension ability of Streptococcus parasanguis.