title: A comparative biochemical and structural analysis of the intracellular chorismate mutase (Rv0948c) from Mycobacterium tuberculosis H(37)R(v) and the secreted chorismate mutase (y2828) from Yersinia pestis.
abstract: The Rv0948c gene from Mycobacterium tuberculosis H(37)R(v) encodes a 90 amino acid protein as the natural gene product with chorismate mutase (CM) activity. The protein, 90-MtCM, exhibits Michaelis-Menten kinetics with a k(cat) of 5.5+/-0.2s(-1) and a K(m) of 1500+/-100microm at 37 degrees C and pH7.5. The 2.0A X-ray structure shows that 90-MtCM is an all alpha-helical homodimer (Protein Data Bank ID: 2QBV) with the topology of Escherichia coli CM (EcCM), and that both protomers contribute to each catalytic site. Superimposition onto the structure of EcCM and the sequence alignment shows that the C-terminus helix3 is shortened. The absence of two residues in the active site of 90-MtCM corresponding to Ser84 and Gln88 of EcCM appears to be one reason for the low k(cat). Hence, 90-MtCM belongs to a subfamily of alpha-helical AroQ CMs termed AroQ(delta.) The CM gene (y2828) from Yersinia pestis encodes a 186 amino acid protein with an N-terminal signal peptide that directs the protein to the periplasm. The mature protein, *YpCM, exhibits Michaelis-Menten kinetics with a k(cat) of 70+/-5s(-1) and K(m) of 500+/-50microm at 37 degrees C and pH7.5. The 2.1A X-ray structure shows that *YpCM is an all alpha-helical protein, and functions as a homodimer, and that each protomer has an independent catalytic unit (Protein Data Bank ID: 2GBB). *YpCM belongs to the AroQ(gamma) class of CMs, and is similar to the secreted CM (Rv1885c, *MtCM) from M.tuberculosis.
authors: National Institute of Standards and Technology, Gaithersburg, MD, USA.
authors: Sook-Kyung
authors: SK
authors: Kim
authors: Sathyavelu K
authors: SK
authors: Reddy
authors: Bryant C
authors: BC
authors: Nelson
authors: Howard
authors: H
authors: Robinson
authors: Prasad T
authors: PT
authors: Reddy
authors: Jane E
authors: JE
authors: Ladner
mesh_terms: D002826:Chorismate Mutase / Q000737:chemistry* / Q000145:classification / Q000378:metabolism; D003001:Cloning, Molecular; D003460:Crystallization; D018360:Crystallography, X-Ray; D007700:Kinetics; D008958:Models, Molecular; D009169:Mycobacterium tuberculosis / Q000201:enzymology; D015010:Yersinia pestis / Q000201:enzymology
chemical_list: D002826:Chorismate Mutase