The 1.3 A crystal structure of the flavoprotein YqjM reveals a novel class of Old Yellow Enzymes.

Here we report the crystal structure of YqjM, a homolog of Old Yellow Enzyme (OYE) that is involved in the oxidative stress response of Bacillus subtilis. In addition to the oxidized and reduced enzyme form, the structures of complexes with p-hydroxybenzaldehyde and p-nitrophenol, respectively, were solved. As for other OYE family members, YqjM folds into a (alpha/beta)8-barrel and has one molecule of flavin mononucleotide bound non-covalently at the COOH termini of the beta-sheet.

Structural and functional impairment of an Old Yellow Enzyme homologue upon affinity tag incorporation.

Recently, it has been reported that the previously uncharacterized YqjM protein from Bacillus subtilis is a true homologue of the physiologically enigmatic yeast Old Yellow Enzyme (OYE). In this study, it was also demonstrated that YqjM is involved in the oxidative stress response of B. subtilis, thus highlighting a novel direction to pursue the role of the OYE family of proteins in the cell.

Crystal structure of the DegS stress sensor: How a PDZ domain recognizes misfolded protein and activates a protease.

Gram-negative bacteria respond to misfolded proteins in the cell envelope with the sigmaE-driven expression of periplasmic proteases/chaperones. Activation of sigmaE is controlled by a proteolytic cascade that is initiated by the DegS protease. DegS senses misfolded protein in the periplasm, undergoes autoactivation, and cleaves the antisigma factor RseA.

Mechanism of chorismate synthase. Role of the two invariant histidine residues in the active site.

Chorismate synthase catalyzes the last step in the common shikimate pathway leading to aromatic compounds such as the aromatic amino acids. The reaction consists of the 1,4-anti-elimination of the 3-phosphate group and the C-(6proR) hydrogen from 5-enolpyruvylshikimate 3-phosphate to yield chorismate. Although this reaction does not involve a net redox change, the enzyme has an absolute requirement for reduced flavin mononucleotide, which is not consumed during the reaction.