Helmstaedt, Kerstin and Heinrich, Gabriele and Merkl, Rainer and Braus, Gerhard H. (2004) Chorismate mutase of Thermus thermophilus is a monofunctional AroH class enzyme inhibited by tyrosine. Archives of Microbiology 181 (3), pp. 195-203.
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aroG, encoding the monofunctional chorismate mutase (TtCM) of the thermophilic gram-negative bacterium Thermus thermophilus, was cloned and its gene product characterized. TtCM was purified to homogeneity on an SDS polyacrylamide gel as a His-fusion protein with a deduced molecular mass of 15.8 kDa. The enzyme belongs to the rare group of AroH-type chorismate mutases which are mainly found in gram-positive bacteria of the Bacillus/ Clostridia group and have recently also been described for gram-negative organisms. The native molecular mass is consistent with a pseudo-alpha/beta barrel enzyme that is organized as a trimer. Comparison of the enzyme's structure with that of its mesophilic counterpart from Bacillus revealed an increase in hydrophilicity on the protein's surface, greater hydrophobicity in cavities within the protein, and greater restriction of conformational freedom, features that contribute to the thermal stability of this chorismate mutase. The kinetic data show Michaelis-Menten substrate saturation with a Km of 290 microM, and a kcat/ Km value of 180 s(-1) mM(-1). TtCM was inhibited by tyrosine with a Ki =34 microM, possibly in a competitive manner.
|Institutions:||Biology, Preclinical Medicine > Institut für Biophysik und physikalische Biochemie > Prof. Dr. Reinhard Sterner > Arbeitsgruppe PD Dr. Rainer Merkl|
|Keywords:||Amino Acid Sequence Chorismate Mutase/antagonists & inhibitors/chemistry/genetics/*metabolism Cloning, Molecular DNA, Bacterial/chemistry/isolation & purification Enzyme Inhibitors/pharmacology Enzyme Stability Genes, Bacterial Kinetics Models, Molecular Molecular Sequence Data Molecular Weight Phylogeny Protein Conformation Protein Subunits/physiology Recombinant Proteins/metabolism Research Support, Non-U.S. Gov't Sequence Alignment Sequence Analysis, DNA Sequence Homology, Amino Acid Thermus thermophilus/*enzymology/*genetics Tyrosine/*pharmacology|
|Subjects:||500 Science > 570 Life sciences|
|Refereed:||Yes, this version has been refereed|
|Created at the University of Regensburg:||No|
|Deposited On:||13 Nov 2009 13:25|
|Last Modified:||21 Dec 2009 07:46|