title: LysGH15B, the SH3b domain of staphylococcal phage endolysin LysGH15, retains high affinity to staphylococci.
abstract: LysGH15, a phage endolysin, exhibits a particularly broad lytic spectrum against Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA). Sequence analysis reveals that this endolysin contains a C-terminal cell wall binding domain (SH3b), which causes the endolysin to bind to host strains. In this study, the substrate binding affinity of the SH3b domain (LysGH15B) was evaluated. A fusion protein of LysGH15B and green fluorescent protein (LysGH15B-GFP) were cloned and expressed in Escherichia coli. Laser scanning confocal microscopy was used to detect the fluorescence of the treated cells irradiated at different excitation wavelengths and to determine the binding activity of LysGH15B-GFP and GFP. We found that LysGH15B-GFP not only generated green fluorescence, but, more importantly, also displayed specific affinity to staphylococcal isolates, especially MRSA. In contrast, the single GFP did not display any binding activity. The high affinity was attributed to the portion of LysGH15B and the binding activity of the fusion protein was specific to staphylococci. This study provides an insight into the SH3b domain of LysGH15. The specific binding activity may cause LysGH15B to serve as an anchoring device, and offer an alternative approach for cell surface attachment onto staphylococci.
authors.affiliation: College of Animal Science and Veterinary Medicine, Jilin University, Changchun 130062, People's Republic of China.
authors.forename: Jingmin
authors.initials: J
authors.lastname: Gu
authors.forename: Rong
authors.initials: R
authors.lastname: Lu
authors.forename: Xiaohe
authors.initials: X
authors.lastname: Liu
authors.forename: Wenyu
authors.initials: W
authors.lastname: Han
authors.forename: Liancheng
authors.initials: L
authors.lastname: Lei
authors.forename: Yu
authors.initials: Y
authors.lastname: Gao
authors.forename: Honglei
authors.initials: H
authors.lastname: Zhao
authors.forename: Yue
authors.initials: Y
authors.lastname: Li
authors.forename: Yuwen
authors.initials: Y
authors.lastname: Diao
mesh_terms: D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D055624:Methicillin-Resistant Staphylococcus aureus / Q000821:virology*; D018613:Microscopy, Confocal; D013203:Staphylococcal Infections / Q000382:microbiology; D013204:Staphylococcus Phages / Q000378:metabolism*; D018909:src Homology Domains
chemical_list: D010450:Endopeptidases; C001143:endolysin