PROTEOLYSIS IN HETEROCYST-FORMING CYANOBACTERIA - CHARACTERIZATION OFA FURTHER ENZYME WITH TRYPSIN-LIKE SPECIFICITY, AND OF A PROLYL ENDOPEPTIDASE FROM ANABAENA-VARIABILIS

Soluble extracts of the cyanobacterium Anabaena variabilis ATCC 29413 and an engineered mutant that lacks an intracellular protease cleaving after Lys and Arg (Maldener, Lockau, Cai, and Wolk, Mel. Gen. Genet. 225, 113-120 (1991)) were separated by ion exchange chromatography, an d protease profiles determined using azocasein, N alpha-benzoyl-D,L-ar ginine-4-nitroanilide and N-carbobenzoxy-glycyl-L-proline-4-nitroanili de as substrates. A second enzyme cleaving at the carboxyl side of lys ine and arginine, and a prolyl endopeptidase were detected, enriched a nd characterized. Both proteolytic enzymes appear to be located in the periplasm.