View source for 1hzu

[[Image:1hzu.jpg|left|200px]]<br /><applet load="1hzu" size="450" color="white" frame="true" align="right" spinBox="true" 
caption="1hzu, resolution 2.70&Aring;" />
'''DOMAIN SWING UPON HIS TO ALA MUTATION IN NITRITE REDUCTASE OF PSEUDOMONAS AERUGINOSA'''<br />

==Overview==
The nitrite reductase (NIR) from Pseudomonas aeruginosa (NIR-Pa) is a, soluble enzyme catalysing the reduction of nitrite (NO2(-)) to nitric, oxide (NO). The enzyme is a 120 kDa homodimer, in which the monomers carry, a c-heme domain and a d(1)-heme domain. The structures of the enzyme in, both the oxidised and reduced state were solved previously and indicate, His327 and His369 as putative catalytic residues. The kinetic, characterisation of site-directed mutants has shown that the substitution, of either one of these two His with Ala dramatically reduces the, physiologically relevant reactivity towards nitrite, leaving the, reactivity towards oxygen unaffected. The three-dimensional structures of, P. aeruginosa NIR mutant H327A, and H369A in complex with NO have been, solved by multiple wavelength anomalous dispersion (MAD), using the iron, anomalous signal, and molecular replacement techniques. In both refined, crystal structures the c-heme domain, whilst preserving its classical, c-type cytochrome fold, has undergone a 60 degrees rigid-body rotation, around an axis parallel with the pseudo 8-fold axis of the beta-propeller, and passing through residue Gln115. Even though the distance between the, Fe ions of the c and d(1)-heme remains 21 A, the edge-to-edge distance, between the two hemes has increased by 5 A. Furthermore the distal side of, the d(1)-heme pocket appears to have undergone structural re-arrangement, and Tyr10 has moved out of the active site. In the H369A-NO complex, the, position and orientation of NO is significantly different from that of the, NO bound to the reduced wild-type structure. Our results provide insight, into the flexibility of the enzyme and the distinction between nitrite and, oxidase reduction mechanisms. Moreover they demonstrate that the two, histidine residues play a crucial role in the physiological activity of, nitrite reduction, ligand binding and in the structural organisation of, nitrite reductase from P. aeruginosa.

==About this Structure==
1HZU is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_aeruginosa Pseudomonas aeruginosa] with HEC and DHE as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Nitrite_reductase_(NO-forming) Nitrite reductase (NO-forming)], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.7.2.1 1.7.2.1] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1HZU OCA]. 

==Reference==
Domain swing upon His to Ala mutation in nitrite reductase of Pseudomonas aeruginosa., Brown K, Roig-Zamboni V, Cutruzzola' F, Arese M, Sun W, Brunori M, Cambillau C, Tegoni M, J Mol Biol. 2001 Sep 21;312(3):541-54. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=11563915 11563915]
[[Category: Nitrite reductase (NO-forming)]]
[[Category: Pseudomonas aeruginosa]]
[[Category: Single protein]]
[[Category: Brown, K.]]
[[Category: Brunori, M.]]
[[Category: Cambillau, C.]]
[[Category: Cutruzzola, F.]]
[[Category: Tegoni, M.]]
[[Category: DHE]]
[[Category: HEC]]
[[Category: 8 bladed beta propeller]]
[[Category: cytochrome c]]

''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 16:56:22 2007''