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Research was conducted to examine the crystal structure of retinal dehydrogenase type II complexed with nicotinamide adenine dinucleotide at 2.7 angstroms resolution using X-ray crystallography. The molecular replacement using the crystal structure of a mitochondrial aldehyde dehydrogenase (ADLDH2) as a model solved the structure. The enzyme apparently uses a disordered stretch of approximately 20 amino acids to limit access to the catalytic site by smaller aldehydes.

The crystollographic structure of human retinol-binding protein (RBP) and transthyretin (TTR) was examined via the use of four amino acids: Val-20, Arg-21, Ile-84 and Leu-82. The results revealed an interaction, which involves Leu-183 and -182 of RBP, of the carboxy terminus of RBP at the protein-protein recognition interface. Prevention of the extensive loss of RBP via glomerular filtration was attributed to complex formation. Moreover, a decrease affinity of RBP for TTR was attributed to the loss of Leu-182 and -183.

A study examined the interaction of a hydrogen bond donor and an aromatic ring receptor in a highly homologous pair of proteins, cellular retinol-binding protein (CRBP) and cellular retinol-binding protein, type II (CRBP II). Both proteins attach the ligand all-trans-retinal with corresponding affinities, but CRBP has more or less 100-fold higher affinity for all-trans-retinol. The greater affinity of CRBP is due to the presence of an amino-aromatic hydrogen bond, which is not found in CRBP(II). Furthermore, the mutant and wild-type CRBP show no preferences for binding all-trans-retinol versus all-trans-retinal.

Two intracellular retinoid-binding proteins, a cellular retinol-binding protein type II, or CRBP(II), and cellular retinol-binding protein (CRBP) react with microsomal enzymes in different ways. The CRBP and CRBP(II) are compact, small and tightly-folded and deliver retinoids to microsomal metabolic enzymes. The difference in the reactions are caused by variation in the structure of the proteins.

The characterization and high resolution structure of a protein that exhibits 60% sequence identity to the plasmid-encoded FosA but is encoded in the genome of the opportunistic pathogen Pseudomonas aeruginosa, is described. The structure is solved exploiting the monovalent cation-binding site for multi-wavelength anomalous diffraction (MAD) phasing with thallium(I).

The article studies 1.85 [angstrom] resolution structure of an 8R-lipoxygenase from Plexaura homomalla, an enzyme with a sequence [approximate]40% identical to that of human 5-LOX. Findings reveal that mutations within the channel significantly affect enzyme activity.

The article explains the functions of the naturally occurring bifunctional protein covalent linker obtained from Plexaura homomalla that links the sequential catalytic activities in an oxylipin biosynthetic complex. The absence of the discussed linker is shown to lead to the formation of a complex that recapitulates the structure of the bifunctional protein.

The structure and mechanisms of action of the genomically encoded FosX enzyme, the fosfomycin resistance protein obtained from Listeria monocytogenes, are described. The results have indicated that both the EGD and ATCC strains of Listeria monocytogenes have an intrinsic resistance to the antibiotic provided by the FosX enzyme.

The structure of the homodimeric state of the Prp19 U-box is determined by X-ray crystallography and it is shown that the U-box domain of Prp19 exists as a dimer within the context of the Prp19 tetramer. The comparison of the Prp19 U-box homodimer with the heterodimeric complex of BRCA1/ BARD1 RING-finger domains shows a common architecture for a family of oligomeric U-box and RING-finder E3 ubiquitin ligases.

Fosfomycin is a simple phosphonate found to have antibacterial activity against both Gram-positive and Gram-negative microorganisms. The study of the FosA-catalyzed reaction reveals that the early transition state and phosphonoformate acts as a minimal transition state analogue inhibitor.

2.3 Armstrong resolution crystal structure of Escherichia coli IscA, the protein responsible for iron-sulfur cluster assembly, is explained. Descriptions reveal that the great majority of amino acids that are conserved in IscA homologues are located in elements that constitute a well-ordered fold.

The crystal structure of the FosX protein from M. loti and Listeria is determined to explain the mechanistic basis of the hydration reaction of fosfomycin. Comparison of antibiotic resistance of FosX, FosA, and Fos B enzymes suggests evolution of fosfomycin resistance protein in Gram-positive and Gram-negative microorganisms.

Antifreeze proteins (AFPs) enhance the survival of organisms inhabiting cold environments by affecting the formation and/or structure of ice. We report the crystal structure of the first multi-domain AFP that has been characterized. The two ice binding domains are structurally similar. Each consists of an irregular β-helix with a triangular cross-section and a long α-helix that runs parallel on one side of the β-helix. Both domains are stabilized by hydrophobic interactions. A flat plane on the same face of each domain’s β-helix was identified as the ice binding site. Mutating any of the smaller residues on the ice binding site to bulkier ones decreased the antifreeze activity. The bulky side chain of Leu174 in domain A sterically hinders the binding of water molecules to the protein backbone, partially explaining why antifreeze activity by domain A is inferior to that of domain B. Our data provide a molecular basis for understanding differences in antifreeze activity between the two domains of this protein and general insight on how structural differences in the ice-binding sites affect the activity of AFPs. [ABSTRACT FROM AUTHOR]