Functional and structural characterization of the 2/2 hemoglobin from Synechococcus sp. PCC 7002.

Cyanobacterium Synechococcus sp. PCC 7002 contains a single gene (glbN) coding for GlbN, a protein of the 2/2 hemoglobin lineage. The precise function of GlbN is not known, but comparison to similar 2/2 hemoglobins suggests that reversible dioxygen binding is not its main activity.

(1)H, (15)N, and (13)C resonance assignments of the 2/2 hemoglobin from the cyanobacterium Synechococcus sp. PCC 7002 in the ferric bis-histidine state.

The hemoglobin from the cyanobacterium Synechococcus sp. PCC 7002 is a monomeric 123-residue Group I 2/2 hemoglobin. Here, we report (1)H, (15)N, and (13)C assignments for the ferric (low-spin, S = (1/2)) protein with a b heme cofactor and after post-translational modification leading to a c-like heme.

Chemical rescue of a site-modified ligand to a [4Fe-4S] cluster in PsaC, a bacterial-like dicluster ferredoxin bound to Photosystem I.

Chemical rescue of site-modified amino acids using externally supplied organic molecules represents a powerful method to investigate structure-function relationships in proteins. Here we provide definitive evidence that aryl and alkyl thiolates, reagents typically used for in vitro iron-sulfur cluster reconstitutions, serve as rescue ligands to a site-specifically modified [4Fe-4S](1+,2+) cluster in PsaC, a bacterial dicluster ferredoxin-like subunit of Photosystem I. PsaC binds two low-potential [4Fe-4S](1+,2+) clusters termed F(A) and F(B).

Structural and dynamic repercussions of heme binding and heme-protein cross-linking in Synechococcus sp. PCC 7002 hemoglobin.

The recombinant two-on-two hemoglobin from the cyanobacterium Synechoccocus sp. PCC 7002 (S7002 rHb) is a bishistidine hexacoordinate globin capable of forming a covalent cross-link between a heme vinyl and a histidine in the C-terminal helix (H helix). Of the two heme axial histidines, His46 (in the E helix, distal side) and His70 (in the F helix, proximal histidine), His46 is displaced by exogenous ligands.

Structural and dynamic properties of Synechocystis sp. PCC 6803 Hb revealed by reconstitution with Zn-protoporphyrin IX.

In its resting state, the truncated globin of the cyanobacterium Synechocystis sp. PCC 6803 exhibits hexacoordination of the heme iron, with His46 (E10) and His70 (F8, proximal) serving as axial ligands. Diatomic ligands displace the distal His46 (E10) from the ferric and ferrous iron and promote considerable structural changes in the B helix, E helix, and EF regions.

Cyanide binding to hexacoordinate cyanobacterial hemoglobins: hydrogen-bonding network and heme pocket rearrangement in ferric H117A Synechocystis hemoglobin.

The truncated hemoglobin (Hb) from the cyanobacterium Synechocystis sp. PCC 6803 is a bis-histidyl hexacoordinate complex in the absence of exogenous ligands. This protein can form a covalent cross-link between His117 in the H-helix and the heme 2-vinyl group.

Structural properties of cyanobacterial hemoglobins: the unusual heme-protein cross-link of Synechocystis sp. PCC 6803 Hb and Synechococcus sp. PCC 7002 Hb.

The truncated hemoglobins from Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7002 ligate the heme iron with two axial histidines (HisF8 and HisE10).

Characterization of the heme-histidine cross-link in cyanobacterial hemoglobins from Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7002.

The recombinant product of the hemoglobin gene of the cyanobacterium Synechocystis sp. PCC 6803 forms spontaneously a covalent bond linking one of the heme vinyl groups to a histidine located in the C-terminal helix (His117, or H16). The present report describes the (1)H, (15)N, and (13)C NMR spectroscopy experiments demonstrating that the recombinant hemoglobin from the cyanobacterium Synechococcus sp.

Partial NMR assignments and secondary structure mapping of the isolated alpha subunit of Escherichia coli tryptophan synthase, a 29-kD TIM barrel protein.

The alpha subunit of tryptophan synthase (alphaTS) from S. typhimurium belongs to the triosephosphate isomerase (TIM) or the (beta/alpha)(8) barrel fold, one of the most common structures in biology. To test the conservation of the global fold in the isolated Escherichia coli homolog, we have obtained a majority of the backbone assignments for the 29-kD alphaTS by using standard heteronuclear multidimensional NMR methods on uniformly (15)N- and (15)N/(13)C-labeled protein and on protein selectively (15)N-labeled at key hydrophobic residues.

The solution structure of the recombinant hemoglobin from the cyanobacterium Synechocystis sp. PCC 6803 in its hemichrome state.

The product of the cyanobacterium Synechocystis sp. PCC 6803 gene slr2097 is a 123 amino acid polypeptide chain belonging to the truncated hemoglobin family. Recombinant, ferric heme-reconstituted Synechocystis sp.

Isolation and characterization of a family of stable RNA tetraloops with the motif YNMG that participate in tertiary interactions.

RNA is known to fold into a variety of structural elements, many of which have sufficient sequence complexity to make the thermodynamic study of each possible variant impractical. We previously reported a method for isolating stable and unstable RNA sequences from combinatorial libraries using temperature gradient gel electrophoresis (TGGE). This method was used herein to analyze a six-nucleotide RNA hairpin loop library.

Truncated hemoglobin from the cyanobacterium Synechococcus sp. PCC 7002: evidence for hexacoordination and covalent adduct formation in the ferric recombinant protein.

The glbN gene for the hemoglobin of Synechoccocus sp. PCC 7002, a cyanobacterium incapable of nitrogen fixation, was cloned and overexpressed in Escherichia coli. The 123-residue protein was purified from inclusion bodies and reconstituted with iron protoporphyrin IX to obtain the ferric form of the holoprotein.