Structure of the has operon promoter and the effect of mutations on the has promoter strength in Streptococcus equi subsp. zooepidemicus.

The purpose of this study is to determine the effect of the corresponding nucleotides from Streptococcus pyogenes on the has promoter strength in highly encapsulated strain S. equi subsp. zooepidemicus (SEZ) and detect an empowering mutations in SEZ. Eight different strains of SEZ carrying nucleotide mutations in the -73 to -38 region upstream of the has promoter were constructed. The significant activity decrease to 36-1% was observed after the introduction of mutations in the promoter region from -44 to -38 site. The exception was observed in mutation in -49 site when no significant decrease was observed. When nucleotides TTT were used in positions -73 the promoter became weaker, whereas no significant effect was observed after using nucleotides CCC (96%). Unfortunately, introduction of these mutations into chromosome SEZ has no empowering effect. Six strains, which carried nucleotide sequences of different lengths upstream from the transcription start of hasA promoter, were constructed to determine the minimum upstream region required for the maximum transcription efficiency of the has operon. No change of the activity of the has promoter constructs containing as few as 101 nucleotides upstream from the transcription start point was observed.