The peculiar heme pocket of the 2/2 hemoglobin of cold-adapted Pseudoalteromonas haloplanktis TAC125

• Main Authors: Boechi, Leonardo, Martí, Marcelo Adrián, Estrin, Dario Ariel
• Language: unknown
• Published: 2011
• Subjects: Antarctic bacterium; EPR; Molecular dynamics; Resonance Raman; Tyrosinate ligand; bacterial protein; hemoglobin; protein TAC125; tryptophan; tyrosine; unclassified drug; article; Bacillus subtilis; cold acclimatization; controlled study; crystal structure; gene overexpression; gene sequence; Geobacillus stearothermophilus; molecular cloning; Mycobacterium tuberculosis; nonhuman; oxidation reduction potential; priority journal; protein analysis; protein purification; protein structure; Pseudoalteromonas; Pseudoalteromonas haloplanktis; Raman spectrometry; sequence alignment; Shewanella oneidensis; simulation; Bacterial Proteins; Electrochemistry; Electron Spin Resonance Spectroscopy; Hemoglobins; Molecular Dynamics Simulation; Oxidation-Reduction; Temperature; Bacteria (microorganisms); Antarctic; Argentina; Antarc*
• Online Access: https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09498257_v16_n2_p299_Howes; https://hdl.handle.net/20.500.12110/paper_09498257_v16_n2_p299_Howes

The genome of the cold-adapted bacterium Pseudoalteromonas haloplanktis TAC125 contains multiple genes encoding three distinct monomeric hemoglobins exhibiting a 2/2 α-helical fold. In the present work, one of these hemoglobins is studied by resonance Raman, electronic absorption and electronic paramagnetic resonance spectroscopies, kinetic measurements, and different bioinformatic approaches. It is the first cold-adapted bacterial hemoglobin to be characterized. The results indicate that this protein belongs to the 2/2 hemoglobin family, Group II, characterized by the presence of a tryptophanyl residue on the bottom of the heme distal pocket in position G8 and two tyrosyl residues (TyrCD1 and TyrB10). However, unlike other bacterial hemoglobins, the ferric state, in addition to the aquo hexacoordinated high-spin form, shows multiple hexacoordinated low-spin forms, where either TyrCD1 or TyrB10 can likely coordinate the iron. This is the first example in which both TyrCD1 and TyrB10 are proposed to be the residues that are alternatively involved in heme hexacoordination by endogenous ligands. © 2010 SBIC. Fil:Boechi, L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Martí, M.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Estrin, D.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.