1d06
From Proteopedia
STRUCTURAL BASIS OF DIMERIZATION AND SENSORY MECHANISMS OF OXYGEN-SENSING DOMAIN OF RHIZOBIUM MELILOTI FIXL DETERMINED AT 1.4A RESOLUTION
Overview
FixL of Rhizobium meliloti (RmFixL) is a sensor histidine kinase of the two-component system, which regulates the expression of the genes related to nitrogen fixation in the root nodule in response to the O(2) levels. The crystal structure of the sensor domain of FixL (RmFixLH), which contains a heme (Fe-porphyrin) as a sensing site, was determined at 1.4 A resolution. Based on the structural and spectroscopic analyses, we propose the O(2) sensing mechanism that differs from the case proposed in BjFixLH as follows; conformational changes in the F/G loop, which are induced by steric repulsion between the bent-bound O(2) and the Ile209 side-chain, would be transmitted to the histidine kinase domain. Interaction between the iron-bound O(2) and Ile209 was also observed in the resonance Raman spectra of RmFixLH as evidenced by the fact that the Fe-O(2) and Fe-CN stretching frequencies were shifted from 575 to 570 cm(-1) (Fe-O(2)), and 504 to 499 cm(-1), respectively, as the result of the replacement of Ile209 with an Ala residue. In the I209A mutant of RmFixL, the O(2) sensing activity was destroyed, thus confirming our proposed mechanism.
About this Structure
1D06 is a Single protein structure of sequence from Sinorhizobium meliloti. Full crystallographic information is available from OCA.
Reference
Sensory mechanism of oxygen sensor FixL from Rhizobium meliloti: crystallographic, mutagenesis and resonance Raman spectroscopic studies., Miyatake H, Mukai M, Park SY, Adachi S, Tamura K, Nakamura H, Nakamura K, Tsuchiya T, Iizuka T, Shiro Y, J Mol Biol. 2000 Aug 11;301(2):415-31. PMID:10926518 Page seeded by OCA on Fri May 2 13:17:50 2008
