IN-VITRO ASSAY FOR THE BACILLUS-SUBTILIS SIGNAL PEPTIDASE SIPS - SYSTEMS FOR EFFICIENT IN-VITRO TRANSCRIPTION-TRANSLATION AND PROCESSING OFPRECURSORS OF SECRETED PROTEINS

The signal peptidase (SPase) SipS of Bacillus subtilis is responsible for the processing of precursors of secreted proteins. It differs from the SPases of Gram-negative bacteria in structure and specificity. To assay the activity of SipS in vitro, two efficient transcription-tran slation systems for the synthesis of radio-labelled precursors were de veloped. The systems were completely derived from B. subtilis. Post-tr anslational in vitro processing of pre-staphylokinase by SipS was demo nstrated. SipS activity was stimulated in vitro by several non-ionic d etergents, whereas it was not affected by a large variety of proteinas e inhibitors. SipS shares the latter property with other SPases.