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
The Rv0948c gene from Mycobacterium tuberculosis H{sub 37}R{sub 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{sub cat} of 5.5 {+-} 0.2 s{sup -1} and a K{sub m} of 1500 {+-} 100 {micro}m at 37 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{sub 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{sub cat} of 70 {+-} 5 s{sup -1} and Km of 500 {+-} 50 {micro}m at 37 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.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE SC OFFICE OF SCIENCE (SC)
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1041640
- Report Number(s):
- BNL-97318-2012-JA; TRN: US201212%%58
- Journal Information:
- FEBS Journal, Vol. 275, Issue 19
- Country of Publication:
- United States
- Language:
- English
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