FIGURE 1.

Construction of non-polar stp mutants in M1SF370 and M1T1 strains. A, schematic representation of the genome organizations of wild-type and mutant strains of S. pyogenes stp/stk operon. The numbers and arrows depict the primers used for confirming gene deletion in the mutants. The indicated nucleotide sequence shows the replacement of the stp gene with the sequence encoding the kanamycin resistance cassette and uninterrupted stk gene sequence. The transcription terminator after kan^r and the ribosomal binding site for the stk are also highlighted. Shown are growth characteristics of the wild-type M1SF370 (B) and M1T1 (C) in comparison with their respectively derived isogenic mutants and complemented strains, grown in THY. D, the growth profile of stp-overexpressing M1SF370 and M1T1 wild-type strains. Each data point of the spectrophotometrically (A₆₀₀) monitored growth curve represents an average of three independent readings. The panels below each graph represent the cfu of the indicated strains grown until A₆₀₀ = 0.8. Error bars, S.D.