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Rubisco's CO2 cofactor is involved in divalent -metal binding, activity regulation and probably also in the catalytic chemistry. Recent studies of the CO2- and metal-binding site in the absence of phosphorylated ligands provide a structural understanding of the unusual activation mechanism.
Recent NMR structures of bovine immunodeficiency viral TAR RNA–Tat peptide complexes have revealed a new β-hairpin RNA recognition motif. These complexes exhibit intriguing new variations on the recurring themes in nucleic acid recognition.
The difference in amino-acid sequence and inferred molecular mechanisms between the pair of EF-hands in BM-40 and those of other EF-hand proteins force us to reconsider the evolutionary and functional relationships among the members of this diverse family of proteins.
A reagent for affinity labelling of the ATP-binding site in glutathione synthetase captures two flexible glycine-rich loops, revealing their structure.
The crystal structure of zeamatin, and comparisons within the family, suggest most PR-5 proteins have an electrostatically polarized surface which may be responsible for antifungal activity.
The EF-hand is a highly conserved Ca2+-binding motif found in many cytosolic Ca2+-modulated proteins. Here we report the crystal structure at 2.0 Å resolution of the carboxy-terminal domain of human BM-40 (SPARC, osteonectin), an extracellular matrix protein containing an EF-hand pair. The two EF-hands interact canonically but their detailed structures are unusual. In the first EF-hand a one-residue insertion is accommodated by a cis-peptide bond and by substituting a carboxylate by a peptide carbonyl as a Ca2+ ligand. The second EF-hand is stabilized by a disulphide bond. The EF-hand pair interacts tightly with an amphiphilic amino-terminal helix, reminiscent of target peptide binding by calmodulin. The present structure defines a novel protein module occurring in several other extracellular proteins.
