3sj5: Difference between revisions

<StructureSection load='3sj5' size='340' side='right'caption='[[3sj5]], [[Resolution|resolution]] 1.67&Aring;' scene=''>

<table><tr><td colspan='2'>[[3sj5]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Caldanaerobacter_subterraneus_subsp._tengcongensis Caldanaerobacter subterraneus subsp. tengcongensis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3SJ5 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3SJ5 FirstGlance]. <br>

</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.673&#8491;</td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=3sj5 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3sj5 OCA], [https://pdbe.org/3sj5 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3sj5 RCSB], [https://www.ebi.ac.uk/pdbsum/3sj5 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3sj5 ProSAT]</span></td></tr>

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Heme Nitric oxide/OXygen binding (H-NOX) domains have provided a novel scaffold to probe ligand affinity in hemoproteins. Mutation of isoleucine 5, a conserved residue located in the heme-binding pocket of the H-NOX domain from Thermoanaerobacter tengcongensis (Tt H-NOX), was carried out to examine changes in oxygen (O(2))-binding properties. A series of I5 mutants (I5F, I5F/I75F, I5F/L144F, I5F/I75F/L144F) were investigated to probe the role of steric bulk within the heme pocket. The mutations significantly increased O(2) association rates (1.5-2.5-fold) and dissociation rates (8-190-fold) as compared to wild-type Tt H-NOX. Structural changes that accompanied the I5F mutation were characterized using X-ray crystallography and resonance Raman spectroscopy. A 1.67 A crystal structure of the I5F mutant indicated that introducing a phenylalanine at position 5 resulted in a significant shift of the N-terminal domain of the protein, causing an opening of the heme pocket. This movement also resulted in an increased amount of flexibility at the N-terminus and the loop covering the N-terminal helix as indicated by the two conformations of the first six N-terminal amino acids, high B-factors in this region of the protein, and partially discontinuous electron density. In addition, introduction of a phenylalanine at position 5 resulted in increased flexibility of the heme within the pocket and weakened hydrogen bonding to the bound O(2) as measured by resonance Raman spectroscopy. This study provides insight into the critical role of I5 in controlling conformational flexibility and ligand affinity in H-NOX proteins.

Controlling Conformational Flexibility of an O(2)-Binding H-NOX Domain.,Weinert EE, Phillips-Piro CM, Tran R, Mathies RA, Marletta MA Biochemistry. 2011 Jul 15. PMID:21721586<ref>PMID:21721586</ref>

==See Also==

*[[Chemotaxis protein 3D structures|Chemotaxis protein 3D structures]]

*[[Methyl-accepting chemotaxis protein|Methyl-accepting chemotaxis protein]]

== References ==

<references/>

</StructureSection>

[[Category: Caldanaerobacter subterraneus subsp. tengcongensis]]

[[Category: Large Structures]]

[[Category: Marletta MA]]

[[Category: Mathies RA]]

[[Category: Phillips-Piro CM]]

[[Category: Tran R]]

[[Category: Weinert EE]]