Journal Article The presence of two receptor-binding proteins contributes to the wide host range of staphylococcal Twort-like phages

竹内, 一平  ,  Takeuchi, Ippei  ,  長田, 啓太  ,  Osada, Keita  ,  AZAM, AA HAERUMAN  ,  Azam, Aa Haeruman  ,  淺川, 宏章  ,  Asakawa, Hiroaki  ,  宮永, 一彦  ,  Miyanaga, Kazuhiko  ,  丹治, 保典  ,  TANJI, YASUNORI

82 ( No. 19 )  , pp.5763 - 5774 , 2016-09
Description
Thanks to their wide host range and virulence, staphylococcal bacteriophages (phages) belonging to the genus Twortlikevirus(staphylococcal Twort-like phages) are regarded as ideal candidates for clinical application for Staphylococcus aureus infectionsdue to the emergence of antibiotic-resistant bacteria of this species. To increase the usability of these phages, it is necessary tounderstand the mechanism underlying host recognition, especially the receptor-binding proteins (RBPs) that determine hostrange. In this study, we found that the staphylococcal Twort-like phageSA012 possesses at least two RBPs. Genomic analysis offive mutant phages ofSA012 revealed point mutations in orf103, in a region unique to staphylococcal Twort-like phages.Phages harboring mutated ORF103 could not infect S. aureus strains in which wall teichoic acids (WTAs) are glycosylated with-N-acetylglucosamine (-GlcNAc). A polyclonal antibody against ORF103 also inhibited infection bySA012 in the presenceof -GlcNAc, suggesting that ORF103 binds to -GlcNAc. In contrast, a polyclonal antibody against ORF105, a short tail fibercomponent previously shown to be an RBP, inhibited phage infection irrespective of the presence of -GlcNAc. Immunoelectronmicroscopy indicated that ORF103 is a tail fiber component localized at the bottom of the baseplate. From these results, we concludethat ORF103 binds -GlcNAc in WTAs, whereas ORF105, the primary RBP, is likely to bind the WTA backbone. Thesefindings provide insight into the infection mechanism of staphylococcal Twort-like phages.

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