The formation of hydrogen bond in the proximal heme pocket of HemAT-Bs upon ligand binding.
HemAT-Bs is the heme-based O(2) sensor responsible for aerotaxis control in Bacillus subtilis. In this study, we measured the time-resolved resonance Raman spectra of full-length HemAT-Bs wild-type (WT) and Y133F in the deoxy form and the photoproduct after photolysis of CO-bound form. In WT, the nu(Fe-His) band for the 10 ps photoproduct was observed at higher frequency by about 2 cm(-1) compared with that of the deoxy form. This frequency difference is relaxed in hundreds of picoseconds. This time-dependent frequency shift would reflect the conformational change of the protein matrix. On the other hand, Y133F mutant did not show such a substantial nu(Fe-His) frequency shift after photolysis. Since a hydrogen bond to the proximal His induces an up-shift of the nu(Fe-His) frequency, these results indicate that Tyr133 forms a hydrogen bond to the proximal His residue upon the ligand binding. We discuss a functional role of this hydrogen bond formation for the signal transduction in HemAT-Bs.
Yoshimura
Hideaki
H
Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan.
Yoshioka
Shiro
S
Mizutani
Yasuhisa
Y
Aono
Shigetoshi
S
D001426:Bacterial Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D001665:Binding Sites; D002248:Carbon Monoxide / Q000737:chemistry*; D003198:Computer Simulation; D006418:Heme / Q000737:chemistry*; D000081062:Heme-Binding Proteins; D006420:Hemeproteins / Q000737:chemistry* / Q000648:ultrastructure*; D006860:Hydrogen Bonding; D008024:Ligands; D008956:Models, Chemical; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation
D001426:Bacterial Proteins; D000081062:Heme-Binding Proteins; D006420:Hemeproteins; D008024:Ligands; C404449:heme protein, bacteria; D006418:Heme; D002248:Carbon Monoxide