1IDR

CRYSTAL STRUCTURE OF THE TRUNCATED-HEMOGLOBIN-N FROM MYCOBACTERIUM TUBERCULOSIS

Summary for 1IDR

• Entry DOI: 10.2210/pdb1idr/pdb
• Descriptor: HEMOGLOBIN HBN, PHOSPHATE ION, PROTOPORPHYRIN IX CONTAINING FE, ... (5 entities in total)
• Functional Keywords: truncated hemoglobin fold, oxygen storage-transport complex, oxygen storage/transport
• Biological source: Mycobacterium tuberculosis
• Total number of polymer chains: 2
• Total formula weight: 30510.91

Authors

Milani, M.,Pesce, A.,Ascenzi, P.,Guertin, M.,Bolognesi, M. (deposition date: 2001-04-05, release date: 2001-08-22, Last modification date: 2024-02-07)

Primary citation

Milani, M.,Pesce, A.,Ouellet, Y.,Ascenzi, P.,Guertin, M.,Bolognesi, M.
Mycobacterium tuberculosis hemoglobin N displays a protein tunnel suited for O2 diffusion to the heme.
EMBO J., 20:3902-3909, 2001

PubMed Abstract: Macrophage-generated oxygen- and nitrogen-reactive species control the development of Mycobacterium tuberculosis infection in the host. Mycobacterium tuberculosis 'truncated hemoglobin' N (trHbN) has been related to nitric oxide (NO) detoxification, in response to macrophage nitrosative stress, during the bacterium latent infection stage. The three-dimensional structure of oxygenated trHbN, solved at 1.9 A resolution, displays the two-over-two alpha-helical sandwich fold recently characterized in two homologous truncated hemoglobins, featuring an extra N-terminal alpha-helix and homodimeric assembly. In the absence of a polar distal E7 residue, the O2 heme ligand is stabilized by two hydrogen bonds to TyrB10(33). Strikingly, ligand diffusion to the heme in trHbN may occur via an apolar tunnel/cavity system extending for approximately 28 A through the protein matrix, connecting the heme distal cavity to two distinct protein surface sites. This unique structural feature appears to be conserved in several homologous truncated hemoglobins. It is proposed that in trHbN, heme Fe/O2 stereochemistry and the protein matrix tunnel may promote O2/NO chemistry in vivo, as a M.tuberculosis defense mechanism against macrophage nitrosative stress.

PubMed: 11483493
DOI: 10.1093/emboj/20.15.3902

Experimental method

X-RAY DIFFRACTION (1.9 Å)