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

作者：Kim Sook Kyung; Reddy Sathyavelu K; Nelson Bryant C; Robinson Howard; Reddy Prasad T^*; Ladner Jane E

来源：FEBS Journal, 2008, 275(19): 4824-4835.

DOI：10.1111/j.1742-4658.2008.06621.x

• chorismate mutase
• Mycobacterium tuberculosis
• pathogenesis
• shikimate pathway
• Yersinia pestis

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 +/- 0.2 s(-1) and a K(m) of 1500 +/- 100 mu M at 37 degrees C and pH 7.5. The 2.0 angstrom 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 helix 3 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 +/- 5 s(-1) and K(m) of 500 +/- 50 mu M at 37 degrees C and pH 7.5. The 2.1 angstrom 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.

• 出版日期2008-10