Study on Fap1 glycosylation and maturation regulating by ORF3 coded by fap1-orf4 gene locus of Streptococcus parasanguis

Abstract

Objective To study whether ORF3 coded by fap1-orf4 gene locus of Streptococcus pa-rasanguis is involved in the regulation of Fap1 glycosylation and maturation and to investigate whether ORF3 influences Streptococcus parasanguis adhesion. Methods A gene replacement strategy was adapted to con-struct orf3 alleic replace mutant of Streptococcus parasanguis. Complementation assay and Western blot were used to test Fap1 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 (Mr about 220 × 103) disappeared and were substituted with high molecular weight Fapl (Mr about 470 × 103) in strain VT1774, furthermore, complementation assay showed VT1775, the complementation strain of VT1774, re-stored mature Fapl expression. (3) The binding ability reduced significantly in strain VT1774. Conclusion ORF3 coded byfapl-orf4 gone locus was required for Fap1 glycosylation and maturation in Streptococcus pa-rasanguis, orf3 alleic replacment resulted in Fap1 glycosylation and mature disorder and decreasing of adhen-sion ability of Streptococcus parasanguis. Key words: Streptococcus parasanguis; Glycosylation; ORF3; Adhension