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Förster Resonance Energy Transfer Mapping: A New Methodology to Elucidate Global Structural Features
Published on: March 16, 2022
Structure-function relationships in Escherichia coli adenylate cyclase.
1Department of Pharmacology, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10065, USA. jul2015@med.cornell.edu
The Biochemical Journal
|July 16, 2008
Summary
Class I adenylate cyclases are crucial for bacterial processes. This study identifies key catalytic residues in E. coli adenylate cyclase, revealing a two-metal-ion mechanism and substrate binding roles.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Class I adenylate cyclases are vital enzymes in gamma- and delta-proteobacteria.
- These enzymes regulate critical cellular functions, including catabolite repression and virulence.
- Understanding their catalytic mechanisms is essential for deciphering bacterial physiology and pathogenesis.
Purpose of the Study:
- To elucidate the catalytic mechanism and substrate interactions of Class I adenylate cyclases.
- To identify and characterize essential residues involved in the catalysis of Escherichia coli adenylate cyclase.
Main Methods:
- Overexpression and purification of the catalytic domain of E. coli adenylate cyclase.
- Enzyme kinetics studies, including Vmax and Km determination.
- Site-directed mutagenesis to identify essential catalytic residues.
- Structural comparison with related enzymes within the nucleotidyltransferase superfamily.
Main Results:
- The E. coli adenylate cyclase catalytic domain exhibited a Vmax of 665 nmol cAMP/mg/min and a Km of 270 microM.
- A two-metal-ion mechanism was proposed, requiring free Mg2+ ions in addition to the MgATP complex.
- Twelve essential catalytic residues were identified, with five (Ser103, Ser113, Asp114, Asp116, Trp118) located in a conserved nucleotidyltransferase region.
- Asp114 and Asp116 were suggested as metal-cofactor-ion-binding residues, and Ser103 was implicated in ATP binding.
Conclusions:
- The study provides mechanistic insights into Class I adenylate cyclase function.
- Specific residues, particularly Ser103, Asp114, and Asp116, are critical for catalysis and substrate binding.
- The findings highlight conserved catalytic strategies across the DNA polymerase beta-like nucleotidyltransferase superfamily.
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