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Biochemical and Structural Characterization of the Intracellular Chorismate Mutase (Rv0948c) From Mycobacterium Tuberculosis H37Rv

Published

Author(s)

Sung Kim, Sathyavelu K. Reddy, B C. Nelson, Prasad T. Reddy, Jane E. Ladner

Abstract

The Rv0948c gene from Mycobacterium tuberculosis H37Rv (Mt) encodes a 105 amino acid (aa) protein with chorismate mutase (CM) activity. Since the protein s amino terminus does not align with other CMs, we cloned a truncated version of the gene that yielded the protein beginning with Met16 (90 aa protein). Both proteins exhibit CM activity with identical kinetic parameters having a kcat of 7 s-1 and a Km of 1.5 0.1 mM at 37 oC and pH 7.5. Only the 90 aa protein, termed MtCM, produced crystals of diffraction quality to 2.0 resolution. MtCM exhibits two protomers in the molecule with all a-helical intertwined structure (PDB ID: 2QBV) having a topology similar to that of Escherichia coli CM (EcCM). However, superimposition of the structure of MtCM onto that of EcCM as well as the sequence alignment shows a shortened version of helix 3 in the carboxyl terminus of MtCM. The missing catalytic residues in helix 3 of MtCM corresponding to Ser84 and Gln88 of EcCM appear to be the reason for low kcat exhibited by MtCM. Hence, MtCM belongs to a new sub-family of a-helical class of AroQ CMs.
Citation
Journal of Biological Chemistry

Keywords

amino acid biosynthesis, AroQ protein, Chorismate mutase, Mycobacterium tuberculosis

Citation

Kim, S. , Reddy, S. , Nelson, B. , Reddy, P. and Ladner, J. (2021), Biochemical and Structural Characterization of the Intracellular Chorismate Mutase (Rv0948c) From Mycobacterium Tuberculosis H<sub>37</sub>R<sub>v</sub>, Journal of Biological Chemistry (Accessed April 21, 2024)
Created October 12, 2021