title: Secreted adenylate cyclase of Bordetella pertussis: calmodulin requirements and partial purification of two forms.
abstract: The extracellular adenylate cyclase of Bordetella pertussis was partially purified and found to contain high- and low-molecular-weight species. The high-molecular-weight form had a variable molecular weight with a peak at about 700,000. The smaller species had a molecular weight of 60 to 70,000 as determined by gel filtration. The low-molecular-weight form could be derived from the high-molecular-weight species. The high-molecular-weight complex purified from the cellular supernatant was highly stimulated by calmodulin, while the low-molecular-weight enzyme was much less stimulated. Active enzyme could be recovered from sodium dodecyl sulfate (SDS) gels at positions corresponding to molecular weights of about 50,000 and 65,000. Active low-molecular-weight enzyme recovered from SDS gels migrated with a molecular weight of about 50,000, which coincides with a coomassie blue-stained band. However, when both high- and low-molecular weight preparations were analyzed in 8 M urea isoelectrofocusing gels, the enzyme activity recovered did not comigrate with stained protein bands. The enzyme recovered from denaturing isoelectrofocusing or SDS gels was activated by calmodulin, indicating a direct interaction of calmodulin and enzyme. The high-molecular-weight form of the enzyme showed increasing activity with calmodulin concentrations ranging from 0.1 to 500 nM, while the low-molecular-weight form was fully activated by calmodulin at 20 nM. Adenylate cyclase on the surface of living cells was activated by calmodulin in a manner which resembled that found for the high-molecular-weight form.
authors.forename: R H
authors.initials: RH
authors.lastname: Kessin
authors.forename: J
authors.initials: J
authors.lastname: Franke
mesh_terms: D000262:Adenylyl Cyclases / Q000032:analysis / Q000302:isolation & purification*; D001886:Bordetella pertussis / Q000201:enzymology*; D002147:Calmodulin / Q000378:metabolism* / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D007457:Iodine Radioisotopes; D007525:Isoelectric Focusing; D007700:Kinetics; D008970:Molecular Weight
chemical_list: D002147:Calmodulin; D007457:Iodine Radioisotopes; D000262:Adenylyl Cyclases