title: Isolation and characterization of proline peptidase mutants of Salmonella typhimurium.
abstract: The proline requirement of Salmonella typhimurium strain proB25 can be satisfied by either of the peptides Leu-Pro or Gly-Pro-Ala. A mutant derivative of strain proB25 isolated by penicillin selection in medium containing Leu-Pro as proline source fails to use either Leu-Pro or Gly-Pro-Ala as a source of proline. This strain is a double mutant that lacks two aminoacyl-proline-specific peptidases. One of these enzymes (peptidase Q) catalyzes the rapid hydrolysis of Leu-Pro but does not hydrolyze Gly-Pro-Ala or poly-l-proline. Mutations at a site (pepQ) near metE lead to loss of this activity. The other peptidase (peptidase P) catalyzes the hydrolysis of Gly-Pro-Ala and poly-l-proline but is only weakly active with Leu-Pro as substrate. This enzyme is similar to aminopeptidase P previously described in Escherichia coli (16). Mutations at a locus (pepP) near serA lead to loss of this enzyme.
mesh_terms: D000626:Aminopeptidases / Q000378:metabolism*; D002474:Cell-Free System; D002874:Chromosome Mapping; D003035:Cobalt / Q000494:pharmacology; D003227:Conjugation, Genetic; D004151:Dipeptides / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D008040:Genetic Linkage; D006868:Hydrolysis; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D009153:Mutagens; D009154:Mutation; D009604:Nitrosoguanidines; D011392:Proline; D012486:Salmonella typhimurium / Q000201:enzymology* / Q000302:isolation & purification; D014161:Transduction, Genetic
chemical_list: D004151:Dipeptides; D009153:Mutagens; D009604:Nitrosoguanidines; D003035:Cobalt; D008345:Manganese; D011392:Proline; D000626:Aminopeptidases; D008274:Magnesium