2BMV: Apoflavodoxin from Helicobacter pylori

Citation:
Abstract
Flavodoxins, noncovalent complexes between apoflavodoxins and flavin mononucleotide (FMN), are useful models to investigate the mechanism of protein/flavin recognition. In this respect, the only available crystal structure of an apoflavodoxin (that from Anabaena) showed a closed isoalloxazine pocket and the presence of a bound phosphate ion, which posed many questions on the recognition mechanism and on the potential physiological role exerted by phosphate ions. To address these issues we report here the X-ray structure of the apoflavodoxin from the pathogen Helicobacter pylori. The protein naturally lacks one of the conserved aromatic residues that close the isoalloxazine pocket in Anabaena, and the structure has been determined in a medium lacking phosphate. In spite of these significant differences, the isoallozaxine pocket in H. pylori apoflavodoxin appears also closed and a chloride ion is bound at a native-like FMN phosphate site. It seems thus that it is a general characteristic of apoflavodoxins to display closed, non-native, isoalloxazine binding sites together with native-like, rather promiscuous, phosphate binding sites that can bear other available small anions present in solution. In this respect, both binding energy hot spots of the apoflavodoxin/FMN complex are initially unavailable to FMN binding and the specific spot for FMN recognition may depend on the dynamics of the two candidate regions. Molecular dynamics simulations show that the isoalloxazine binding loops are intrinsically flexible at physiological temperatures, thus facilitating the intercalation of the cofactor, and that their mobility is modulated by the anion bound at the phosphate site.
PDB ID: 2BMVDownload
MMDB ID: 39609
PDB Deposition Date: 2005/3/16
Updated in MMDB: 2012/11
Experimental Method:
x-ray diffraction
Resolution: 2.11  Å
Source Organism:
Similar Structures:
Biological Unit for 2BMV: monomeric; determined by author and by software (PQS)
Molecular Components in 2BMV
Label Count Molecule
Protein (1 molecule)
1
Flavodoxin(Gene symbol: HP1161)
Molecule annotation
Chemicals (2 molecules)
1
1
2
1
* Click molecule labels to explore molecular sequence information.

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