Sensory Mechanism of Oxygen Sensor FixL.
نویسندگان
چکیده
منابع مشابه
A proximal arginine R206 participates in switching of the Bradyrhizobium japonicum FixL oxygen sensor.
In oxygen-sensing PAS domains, a conserved polar residue on the proximal side of the heme cofactor, usually arginine or histidine, interacts alternately with the protein in the "on-state" or the heme edge in the "off-state" but does not contact the bound ligand directly. We assessed the contributions of this residue in Bradyrhizobium japonicum FixL by determining the effects of an R206A substit...
متن کاملRole of arginine 220 in the oxygen sensor FixL from Bradyrhizobium japonicum.
In the heme-based oxygen sensor protein FixL, conformational changes induced by oxygen binding to the heme sensor domain regulate the activity of a neighboring histidine kinase, eventually restricting expression of specific genes to hypoxic conditions. The conserved arginine 220 residue is suggested to play a key role in the signal transduction mechanism. To obtain detailed insights into the ro...
متن کاملADP reduces the oxygen-binding affinity of a sensory histidine kinase, FixL: the possibility of an enhanced reciprocating kinase reaction.
The rhizobial FixL/FixJ system, a paradigm of heme-based oxygen sensors, belongs to the ubiquitous two-component signal transduction system. Oxygen-free (deoxy) FixL is autophosphorylated at an invariant histidine residue by using ATP and catalyzes the concomitant phosphoryl transfer to FixJ, but oxygen binding to the FixL heme moiety inactivates the kinase activity. Here we demonstrate that AD...
متن کاملAssignment of the hyperfine-shifted 1H-NMR signals of the heme in the oxygen sensor FixL from Rhizobium meliloti.
BACKGROUND [corrected] The Rhizobial oxygen sensor FixL is a hemoprotein with kinase activity. On binding of strong-field ligands, a change of the ferrous or ferric heme iron from high to low spin reversibly inactivates the kinase. This spin-state change and other information on the heme pocket have been inferred from enzymatic assays, absorption spectra and mutagenesis studies. We set out to i...
متن کاملThe FixL protein of Rhizobium meliloti can be separated into a heme-binding oxygen-sensing domain and a functional C-terminal kinase domain.
Transcription of nitrogen fixation (nif and fix) genes in Rhizobium meliloti is induced by a decrease in oxygen concentration. The products of two genes, fixL and fixJ, are responsible for sensing and transmitting the low-oxygen signal. The proteins encoded by fixL and fixJ (FixL and FixJ, respectively) are homologous to a family of bacterial proteins that transduce environmental signals throug...
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ژورنال
عنوان ژورنال: Nihon Kessho Gakkaishi
سال: 2001
ISSN: 0369-4585,1884-5576
DOI: 10.5940/jcrsj.43.158