title: Polyphosphates from Mycobacterium bovis--potent inhibitors of class III adenylate cyclases.
abstract: cAMP generation in bacteria is often stimulated by sudden, but lasting, changes in extracellular conditions, whereas intracellular cAMP concentrations quickly settle at new levels. As bacteria lack G-proteins, it is unknown how bacterial adenylate cyclase (AC) activities are modulated. Mycobacterium tuberculosis has 15 class III AC genes; therefore, we examined whether mycobacteria contain a factor that may regulate AC activities. We identified mycobacterial polyphosphates with a mean chain length of 72 residues as highly potent inhibitors of dimeric class IIIa, class IIIb and class IIIc ACs from M. tuberculosis and other bacteria. The identity of the inhibitor was established by phosphatase degradation, 31P-NMR, acid or base hydrolysis, PAGE and comparisons with commercial standards, and functional substitution by several polyphosphates. The data indicate that each AC dimer occupies 8-15 phosphate residues on a polyphosphate strand. Other polyionic polymers such as polyglutamate, polylysine and hyaluronic acid do not affect cyclase activity. Notably, the structurally unrelated class I AC Cya from Escherichia coli is unaffected. Bacterial polyphosphate metabolism is generally viewed in the context of stress-related regulatory networks. Thus, regulation of bacterial class III ACs by polyphosphates could be a component of the bacterial stress response.
authors.affiliation: Pharmazeutisches Institut, Universität Tübingen, Germany.
authors.forename: Ying Lan
authors.initials: YL
authors.lastname: Guo
authors.forename: Hermann
authors.initials: H
authors.lastname: Mayer
authors.forename: Waldemar
authors.initials: W
authors.lastname: Vollmer
authors.forename: Dorothea
authors.initials: D
authors.lastname: Dittrich
authors.forename: Peter
authors.initials: P
authors.lastname: Sander
authors.forename: Anita
authors.initials: A
authors.lastname: Schultz
authors.forename: Joachim E
authors.initials: JE
authors.lastname: Schultz
mesh_terms: D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000737:chemistry; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors*; D000242:Cyclic AMP / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D009163:Mycobacterium bovis / Q000737:chemistry*; D009169:Mycobacterium tuberculosis / Q000201:enzymology; D011122:Polyphosphates / Q000737:chemistry* / Q000302:isolation & purification; D055503:Protein Multimerization; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D011122:Polyphosphates; D011994:Recombinant Proteins; D000242:Cyclic AMP; D000262:Adenylyl Cyclases