Evidence for a multimeric subtilin synthetase complex

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Subtilin is a lantibiotic produced by Bacillus subtilis.
• It is synthesized as a prepeptide and undergoes posttranslational modification.
• Key proteins SpaB, SpaC, and SpaT are implicated in subtilin's modification and transport.

Purpose of the Study:

• To investigate the roles of SpaB, SpaC, and SpaT proteins in subtilin production.
• To elucidate the regulatory mechanisms controlling the expression of these proteins.
• To determine the interactions between these proteins and the subtilin precursor.

Main Methods:

• Genetic analysis of the subtilin gene cluster.
• Immunoblot and Western blot analysis for protein detection and localization.
• Yeast two-hybrid system and coimmunoprecipitation for protein interaction studies.

Main Results:

• SpaC production is tightly regulated, commencing in the late logarithmic growth phase.
• The spaR and spaK genes form a two-component regulatory system controlling SpaB and SpaC expression.
• SpaB, SpaT, and SpaC are membrane-bound proteins that form a complex with the subtilin precursor, SpaS.

Conclusions:

• The spaR/spaK regulatory system is crucial for subtilin biosynthesis.
• SpaB, SpaC, and SpaT proteins form a functional complex essential for subtilin precursor modification and transport.
• These findings provide insights into the intricate machinery of lantibiotic production in Bacillus subtilis.