Role of the semi-conserved histidine residue in the light-sensing domain of LitR, a MerR-type photosensory transcriptional regulator.
The LitR/CarH protein family transcriptional regulator is a new type of photoreceptor based on the function of adenosyl B12 (AdoB12) as a light-sensitive ligand. Here, we studied a semi-conserved histidine residue (His132) in the light-sensing (AdoB12-binding) domain at the C-terminus of LitR from a thermophilic Gram-negative bacterium, Thermus thermophilus HB27. The in vivo mutation of His132 within LitR caused a reduction in the rate of carotenoid production in response to illumination. BIAcore analysis revealed that the illuminated-LitRH132A possesses high DNA-binding activity compared to the wild-type protein. The subunit structure analysis showed that LitRH132A performed an incomplete subunit dissociation. The ability of LitRH132A to associate with AdoB12 was reduced compared with that of the wild-type protein in an equilibration dialysis experiment. Overall, these results suggest that His132 of LitR is involved in the association with AdoB12 as well as the light-sensitive DNA-binding activity based on oligomer dissociation.
Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-0880, Japan.
Hideaki
H
Takano
Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-0880, Japan.
Kou
K
Mise
Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-0880, Japan.
Takafumi
T
Maruyama
Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-0880, Japan.
Kenta
K
Hagiwara
Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-0880, Japan.
Kenji
K
Ueda
D000595:Amino Acid Sequence / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D006639:Histidine / Q000235:genetics*; D008027:Light; D009154:Mutation / Q000235:genetics; D020283:Photoreceptors, Microbial / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D016415:Sequence Alignment; D016963:Thermus thermophilus / Q000235:genetics* / Q000502:physiology*; D014158:Transcription, Genetic / Q000235:genetics
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C051124:MerR protein, Bacteria; D020283:Photoreceptors, Microbial; D006639:Histidine