DosT and DevS are oxygen-switched kinases in Mycobacterium tuberculosis.
Exposure of Mycobacterium tuberculosis to hypoxia is known to alter the expression of many genes, including ones thought to be involved in latency, via the transcription factor DevR (also called DosR). Two sensory kinases, DosT and DevS (also called DosS), control the activity of DevR. We show that, like DevS, DosT contains a heme cofactor within an N-terminal GAF domain. For full-length DosT and DevS, we determined the ligand-binding parameters and the rates of ATP reaction with the liganded and unliganded states. In both proteins, the heme state was coupled to the kinase such that the unliganded, CO-bound, and NO-bound forms were active, but the O(2)-bound form was inactive. Oxygen-bound DosT was unusually inert to oxidation to the ferric state (half life in air >60 h). Though the kinase activity of DosT was unaffected by NO, this ligand bound 5000 times more avidly than O(2) to DosT (K(d) [NO] approximately 5 nM versus K(d) [O(2)] = 26 microM). These results demonstrate direct and specific O(2) sensing by proteins in M. tuberculosis and identify for the first time a signal ligand for a sensory kinase from this organism. They also explain why exposure of M. tuberculosis to NO donors under aerobic conditions can give results identical to hypoxia, i.e., NO saturates DosT, preventing O(2) binding and yielding an active kinase.
Sousa
Eduardo Henrique Silva
EH
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9038, USA.
Tuckerman
Jason Robert
JR
Gonzalez
Gonzalo
G
Gilles-Gonzalez
Marie-Alda
MA
D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D001665:Binding Sites; D002248:Carbon Monoxide / Q000737:chemistry / Q000378:metabolism; D002413:Cations, Divalent / Q000737:chemistry / Q000378:metabolism; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008024:Ligands; D008954:Models, Biological; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D009569:Nitric Oxide / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D006656:Protamine Kinase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D011494:Protein Kinases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D017434:Protein Structure, Tertiary
D001426:Bacterial Proteins; D002413:Cations, Divalent; D008024:Ligands; D009569:Nitric Oxide; D006418:Heme; D002248:Carbon Monoxide; D000255:Adenosine Triphosphate; D011494:Protein Kinases; C506260:DevS protein, Mycobacterium tuberculosis; D006656:Protamine Kinase; D010100:Oxygen