Receiver domain of sensor histidine kinase CKI1: Difference between revisions

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Tomas Klumpler, Jaime Prilusky, Michal Harel, Alexander Berchansky

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 ==CKI1RD tructure and effects of magnesium binding in the active site==
 <StructureSection load='3mmn' size='400' side='right' caption='CKI1RD bound in magnesium bound form, (PDB entry [[3mmn]])' scene='Receiver_domain/Initial_1/2'>
-The crystal structure of CKI1RD shows the conformational conservation of RDs belonging to CheY-like protein superfamily <ref>PMID:8257674</ref><ref>PMID:19036790</ref>. CKI1RD is folded in a (α/β)5 manner with central β-sheet formed from parallel beta-strands (β2-β1-β3-β4-β5) surrounded on both sides by two (α1 and α5) and three (α2, α3, α4) α-helices. Secondary structure elements are connected by five loops L1-L5 on the face side of the protein. The active site with phosphoacceptor D1050 is located at the C-termini of the central β3-strand in a pocket delineated loops L1, L3 and L5. A highly conserved (<scene name='Receiver_domain/Initial_1/4'> triad of carboxyl oxygens </scene>), formed by D1050 together with D992 and D993 and carbonyl oxygen of Q1052 give the active site an acidic character. This architecture of the active site is well conserved among CheY-like superfamily and corresponds to the phosphotransfer function of the receiver domains.
+The crystal structure of CKI1RD shows the conformational conservation of RDs belonging to CheY-like protein superfamily <ref>PMID:8257674</ref><ref>PMID:19036790</ref>. CKI1RD is folded in a (α/β)5 manner with central β-sheet formed from parallel beta-strands (β2-β1-β3-β4-β5) surrounded on both sides by two (α1 and α5) and three (α2, α3, α4) α-helices. Secondary structure elements are connected by five loops L1-L5 on the face side of the protein. The active site with (<scene name='Receiver_domain/Initial_1/5'> phosphoacceptor D1050 </scene>)
+is located at the C-termini of the central β3-strand in a pocket delineated loops L1, L3 and L5. A highly conserved (<scene name='Receiver_domain/Initial_1/4'> triad of carboxyl oxygens </scene>), formed by D1050 together with D992 and D993 and carbonyl oxygen of Q1052 give the active site an acidic character. This architecture of the active site is well conserved among CheY-like superfamily and corresponds to the phosphotransfer function of the receiver domains.
 [[Image:Structural and sequentional conservation among receiver domains.png.PNG|250px|left|thumb| Conservation of the structure and sequence among known receiver domains. Left: Superimposition of 35 known crystal structures of receiver domains. Right: Representation of highly conserved residues among receiver domains.]]
 The octahedral coordination geometry of magnesium ion in this crystal is not complete. Magnesium ion is four-coordinated with carboxyl oxygens of D993 and D1050, carbonyl oxygen of Q1052 and with one water molecule that forms a hydrogen bridge to the carboxyl oxygen of D992.