CRYSTALLOGRAPHIC STUDIES ON SERRALYSINS. Ulrich Baumann, Institut f. Organische Chemie und Biochemie, Albertstr. 21, D-79104 Freiburg, Germany

The serralysins represent a family of 50 kDa metallo-endoproteinases which are secreted into the medium by Gram-negative bacteria. Examples for members of this family are the proteases B and C from Erwinia chrysanthemi (PrtB and PrtC) the major metallo protease from Serratia marcescens (SMP) and the alkaline protease (AP) from Pseudomonas aeruginosa. The 3D structures of several serralysins, in an unliganded state or in complex with various inhibitors, have been solved and refined to high resolution. Comparison of these structures reveal an induced-fit mechanism in which Tyr216 acts not only a switch to trigger this conformational rearrangement but most likely also as electrophile which stabilizes the transition state.