tailieunhanh - Báo cáo khoa học: A novel thermostable hemoglobin from the actinobacterium Thermobifida fusca

The gene coding for a hemoglobin-like protein (Tf-trHb) has been identi-fied in the thermophilic actinobacteriumThermobifida fuscaand cloned in Escherichia colifor overexpression. The crystal structure of the ferric, ace-tate-bound derivative, was obtained at A ˚ resolution. The three-dimen-sional structure of Tf-trHb is similar to structures reported for the truncated hemoglobins from Mycobacterium tuberculosisandBacillus sub-tilis in its central domain. | ềFEBS Journal A novel thermostable hemoglobin from the actinobacterium Thermobifida fusca Alessandra Bonamore1 Andrea Ilari1 z Laura Giangiacomo1 Andrea Bellelli1 Veronica Morea2 and Alberto Boffi1 1 Department of BiochemicalSciences University of Rome La Sapienza Italy 2 CNR Institute of Molecular Biology and Pathology University of Rome La Sapienza Italy Keywords bacterialhemoglobins heme ligand-binding properties oxygen binding thermostable proteins X-ray structure Correspondence A. Boffi Department of Biochemical Sciences University of Rome La Sapienza P. le Aldo Moro 5 00185 Rome Italy Fax 39 64 44 0062 Tel 39 64 94 0543 E-mail Notes These authors contributed equally to this work The atomic coordinates and structure factors have been deposited in the Protein Data Bank Research Laboratory for Struc-turalBioinformatics Rutgers University New Brunswick http PDB code 2BMM The gene coding for a hemoglobin-like protein Tf-trHb has been identified in the thermophilic actinobacterium Thermobifida fusca and cloned in Escherichia coli for overexpression. The crystal structure of the ferric acetate-bound derivative was obtained at A resolution. The three-dimensional structure of Tf-trHb is similar to structures reported for the truncated hemoglobins from Mycobacterium tuberculosis and Bacillus sub-tilis in its central domain. The complete lack of diffraction patterns relative to the N- and C-terminal segments indicates that these are unstructured polypeptides chains consistent with their facile cleavage in solution. The absence of internal cavities and the presence of two water molecules between the bound acetate ion and the protein surface suggest that the mode of ligand entry is similar to that of typical hemoglobins. The protein is characterized by higher thermostability than the similar mesophilic truncated hemoglobin from B. subtilis as demonstrated by far-UV CD melting experiments on the cyano-met derivatives. The .