Journal: bioRxiv
Article Title: The spike tip protein of bacteriophage T4
doi: 10.1101/2025.08.28.672839
Figure Lengend Snippet: Flowchart of the fractionation procedure. The same nomenclature (colors and abbreviations) is used to label the cellular fractions in panels C and D. B , The two top rows in the left panel show titration of P2 vir1 Vam46 on either C-520 (permissive, supD ) or C-2 (non-permissive) E. coli lawns. The two bottom rows in the left panel show titration of P2 vir1 Vam46 that remained in solution after a 15 min incubation with cells. These cells were subsequently used in the fractionation procedure. The right panel shows quantitative representation (mean ± SD) of the titration presented in the left panel. The experiment was repeated six times with similar outcomes. C , Western blot analysis of cell fractions from cultures which were either uninfected (left section of the blot) or infected with P2 Vir1 V am46 (right section). Each column is a separate fraction of the fractionation procedure shown in panel A . The rows correspond to different antibodies used against cellular proteins with known localizations: GroEL is a soluble cytoplasmic protein, MalE (MBP, maltose binding protein) is a soluble periplasmic protein, OmpF is the outer membrane porin F. GpV co-localizes with MalE. The blot is representative of four biological replicates. D , A Coomassie stained polyacrylamide SDS gel showing a purified P2 Vir1 phage sample (labeled P2) and fractionated lysates of uninfected C-2 cells (labeled N) or infected with P2 Vir1 Vam (labeled I). The red arrow points to the P2 sheath protein; its identity was confirmed by LC/MS/MS analysis. The P2 capsid protein is partially masked by a cellular membrane component with a similar electrophoretic mobility. The inset in a black box (lower right) shows qPCR analysis of P2 genomic DNA (mean ± SD) found in different cellular fractions. The fluorescent signal was converted to the number of plaque forming units (pfus) using a calibration curve as described in the methods section. The experiment was repeated three times with similar outcomes. The significance was determined by Student’s two-tailed t -test with one, two, and three stars (*, **, ***) corresponding to p-values of less than than 0.05, 0.001, and 0.0001, respectively.
Article Snippet: The primary antibodies used were: MalE/MBP-probe antibody (Santa Cruz Biotechnology, sc-13564), GroEL polyclonal antibody (Enzo Life Sciences, ADI-SPS-875-D), OmpF antibody (orb308741, Biorbyt) and a custom made anti-P2 gpV polyclonal antibody generated by GenScript.
Techniques: Fractionation, Titration, Incubation, Western Blot, Infection, Binding Assay, Membrane, Staining, SDS-Gel, Purification, Labeling, Liquid Chromatography with Mass Spectroscopy, Two Tailed Test