Molecular, kinetic, thermodynamic, and structural analyses of Mycobacterium tuberculosis hisD-encoded metal-dependent dimeric histidinol dehydrogenase (EC 1.1.1.23)

• Published in: Archives of biochemistry and biophysics 2011-08, Vol.512 (2), p.143-153
• Main Authors: Nunes, José E S, Ducati, Rodrigo G, Breda, Ardala, Rosado, Leonardo A, de Souza, Bibiana M, Palma, Mario S, Santos, Diógenes S, Basso, Luiz A
• Format: Article
• Language: English
• Subjects: Alcohol Oxidoreductases - chemistry; Alcohol Oxidoreductases - genetics; Alcohol Oxidoreductases - metabolism; Amino Acid Sequence; Archaebacteria; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Base Sequence; Catalytic Domain; Cloning, Molecular; Dimerization; DNA, Bacterial - genetics; Human immunodeficiency virus; Humans; Hydrogen-Ion Concentration; Kinetics; Models, Biological; Models, Molecular; Molecular Sequence Data; Mycobacterium tuberculosis; Mycobacterium tuberculosis - enzymology; Mycobacterium tuberculosis - genetics; Protein Conformation; Protein Structure, Quaternary; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Sequence Homology, Amino Acid; Spectrometry, Mass, Electrospray Ionization; Thermodynamics
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/j.abb.2011.05.020

The emergence of drug-resistant strains of Mycobacterium tuberculosis, the major causative agent of tuberculosis (TB), and the deadly HIV-TB co-infection have led to an urgent need for the development of new anti-TB drugs. The histidine biosynthetic pathway is present in bacteria, archaebacteria, lower eukaryotes and plants, but is absent in mammals. Disruption of the hisD gene has been shown to be essential for M. tuberculosis survival. Here we present cloning, expression and purification of recombinant hisD-encoded histidinol dehydrogenase (MtHisD). N-terminal amino acid sequencing and electrospray ionization mass spectrometry analyses confirmed the identity of homogeneous MtHisD. Analytical gel filtration, metal requirement analysis, steady-state kinetics and isothermal titration calorimetry data showed that homodimeric MtHisD is a metalloprotein that follows a Bi Uni Uni Bi Ping-Pong mechanism. pH-rate profiles and a three-dimensional model of MtHisD allowed proposal of amino acid residues involved in either catalysis or substrate(s) binding.