Fig. 7

Histidine (H161) is crucial for the lytic activity of D. indicus Ami1_Di. (A) Phase contrast micrographs showing cells of strains RP21 (MG1655 ΔamiA::frt ΔamiC::frt /pBAD18), RP102 (MG1655 ΔamiA::frt ΔamiC::frt /pBAD18ami1_Di^1–155aa) and RP103 (MG1655 ΔamiA::frt ΔamiC::frt /pBAD18ami1_Di^H161A). Cells were grown to OD₆₀₀ ∼ 0.2 and induced with 0.4% L-arabinose for 6 h, and cells were immobilized on 1XPBS agarose pad and imaged. (B) Quantitative analysis of phase contrast micrographs (A). Cells were counted as mentioned in Materials and Methods. The absence of the amidase_3 domain (RP102) or inactivation of catalytic activity of the amidase_3 domain by site-directed mutagenesis (RP103) does not complement the chaining phenotype of the RP21 mutant. Datasets are from three independent experiments, and error bars represent standard deviation. P value = RP21 vs. RP102, p > 0.05^*, RP21 vs. RP103, p < 0.05^**. No. of cells – Total number of cells counted for each strain