6BDD

Crystal structure of Fe(II) unliganded H-NOX protein from K. algicida

Summary for 6BDD

• Entry DOI: 10.2210/pdb6bdd/pdb
• Related: 6BDE
• Descriptor: 2,4-dihydroxyhept-2-ene-1,7-dioic acid aldolase, PROTOPORPHYRIN IX CONTAINING FE (3 entities in total)
• Functional Keywords: nitric oxide signaling, heme nitric oxide/oxygen sensing protein, signaling protein
• Biological source: Kordia algicida OT-1
• Total number of polymer chains: 1
• Total formula weight: 21900.67

Authors

Bruegger, J.J.,Hespen, C.W.,Marletta, M.A. (deposition date: 2017-10-22, release date: 2018-05-30, Last modification date: 2023-10-04)

Primary citation

Hespen, C.W.,Bruegger, J.J.,Guo, Y.,Marletta, M.A.
Native Alanine Substitution in the Glycine Hinge Modulates Conformational Flexibility of Heme Nitric Oxide/Oxygen (H-NOX) Sensing Proteins.
ACS Chem. Biol., 13:1631-1639, 2018

PubMed Abstract: Heme nitric oxide/oxygen sensing (H-NOX) domains are direct NO sensors that regulate a variety of biological functions in both bacteria and eukaryotes. Previous work on H-NOX proteins has shown that upon NO binding, a conformational change occurs along two glycine residues on adjacent helices (termed the glycine hinge). Despite the apparent importance of the glycine hinge, it is not fully conserved in all H-NOX domains. Several H-NOX sensors from the family Flavobacteriaceae contain a native alanine substitution in one of the hinge residues. In this work, the effect of the increased steric bulk within the Ala-Gly hinge on H-NOX function was investigated. The hinge in Kordia algicida OT-1 ( Ka H-NOX) is composed of A71 and G145. Ligand-binding properties and signaling function for this H-NOX were characterized. The variant A71G was designed to convert the hinge region of Ka H-NOX to the typical Gly-Gly motif. In activity assays with its cognate histidine kinase (HnoK), the wild type displayed increased signal specificity compared to A71G. Increasing titrations of unliganded A71G gradually inhibits HnoK autophosphorylation, while increasing titrations of unliganded wild type H-NOX does not inhibit HnoK. Crystal structures of both wild type and A71G Ka H-NOX were solved to 1.9 and 1.6 Å, respectively. Regions of H-NOX domains previously identified as involved in protein-protein interactions with HnoK display significantly higher b-factors in A71G compared to wild-type H-NOX. Both biochemical and structural data indicate that the hinge region controls overall conformational flexibility of the H-NOX, affecting NO complex formation and regulation of its HnoK.

PubMed: 29757599
DOI: 10.1021/acschembio.8b00248

Experimental method

X-RAY DIFFRACTION (1.901 Å)