Fig. 6

Inter-subunit carbohydrate-binding site is crucial to CPS depolymerization, phage absorption and infectivity. a Comparison of CPS depolymerization activities of wild-type and mutant K1 lyases evaluated by monitoring the increase of absorbance at 232 nm. b and c Enzyme kinetics study of wild-type K1 lyase and its R472A mutant, respectively. The results of initial velocity are shown as mean ± SD from triplicate experiments. d Kinetic parameters calculated from (b) and (c). e Plaque morphology of wild-type and mutant phages. The NTUH-K2044-K1-1 phage, with or without the mutations at the coding region of the K1 lyase, were spotted on plates pre-inoculated with K1 K. pneumonia NTUH-K2044. f Comparison of plaque sizes of wild-type and mutant phages as evaluated by measuring the diameters of 20 randomly selected plaques. Plaques from the phage with the R472A mutation in the K1 lyase were significantly reduced in size compared to wild type (P < 0.0001, Student’s t-test), whereas the phage with the R378A mutation showed little difference (P = 0.8703). g Comparison of absorption efficiencies of wild-type and mutant phages. The phage with the R472A mutation showed decreased absorption on NTUH-K2044 compared to wild type (P = 0.0013), but the phage with the R378A mutation had nearly no difference (P = 0.1012)