Dynamics of loops at the substrate entry channel determine the specificity of iridoid synthases.

Iridoid synthases belong to the family of short-chain dehydrogenase/reductase involved in the biosynthesis of iridoids. Despite having high sequence and structural homology with progesterone 5β-reductase, these enzymes exhibit differential substrate specificities. Previously, two loops, L1 and L2 at substrate-binding pocket, were suggested to be involved in generating substrate specificity.

Evolution of bacterial ribosomal protein L1.

Search vectors composed of Gly, Ala, Arg, and Pro (GARP) residues retrieve 98% of each of the ribosomal proteins in prokaryotic species with no false hits. Different combinations of G, A, R and P and insertions differentiate each ribosomal protein from all others. Amino acids in two sequence positions separate Gram+ from Gram- bacteria.

The first crystal structure of a gramicidin complex with sodium: high-resolution study of a nonstoichiometric gramicidin D-NaI complex.

The crystal structure of the nonstoichiometric complex of gramicidin D with NaI has been studied using synchrotron radiation at 100 K. The limiting resolution was 1.25 A and the R factor was 16% for 19 883 observed reflections.

The short-chain oxidoreductase Q9HYA2 from Pseudomonas aeruginosa PAO1 contains an atypical catalytic center.

The characteristic oxidation or reduction reaction mechanisms of short-chain oxidoreductase (SCOR) enzymes involve a highly conserved Asp-Ser-Tyr-Lys catalytic tetrad. The SCOR enzyme Q9HYA2 from the pathogenic bacterium Pseudomonas aeruginosa was recognized to possess an atypical catalytic tetrad composed of Lys118-Ser146-Thr159-Arg163. Orthologs of Q9HYA2 containing the unusual catalytic tetrad along with conserved substrate and cofactor recognition residues were identified in 27 additional species, the majority of which are bacterial pathogens.