Staphylococcus aureus Bacteriophage 52 Endolysin Exhibits Anti-Biofilm and Broad Antibacterial Activity Against Gram-Positive Bacteria.

Bacteriophage endolysins have been shown to hold great promise as new antibacterial agents for animal and human health in food preservation. In the present study, endolysin from Staphylococcus aureus subsp. aureus ATCC 27692-B1 bacteriophage 52 (LysSA52) was cloned, expressed, and characterized for its antimicrobial properties.

Increased Turnover at Limiting O2 Concentrations by the Thr(387) → Ala Variant of HIF-Prolyl Hydroxylase PHD2.

PHD2 is a 2-oxoglutarate, non-heme Fe(2+)-dependent oxygenase that senses O2 levels in human cells by hydroxylating two prolyl residues in the oxygen-dependent degradation domain (ODD) of HIF1α. Identifying the active site contacts that determine the rate of reaction at limiting O2 concentrations is crucial for understanding how this enzyme senses pO2 and may suggest methods for chemically altering hypoxia responses. A hydrogen bonding network extends from the Fe(II) cofactor through ordered waters to the Thr(387) residue in the second coordination sphere.

Substrate preference of the HIF-prolyl hydroxylase-2 (PHD2) and substrate-induced conformational change.

HIF prolyl-4-hydroxylase 2 (PHD2) is a non-heme Fe, 2-oxoglutarate (2OG) dependent dioxygenase that regulates the hypoxia inducible transcription factor (HIF) by hydroxylating two conserved prolyl residues in N-terminal oxygen degradation domain (NODD) and C-terminal oxygen degradation domain (CODD) of HIF-1α. Prior studies have suggested that the substrate preference of PHD2 arises from binding contacts with the β2β3 loop of PHD2. In this study we tested the substrate selectivity of PHD2 by kinetic competition assays, varied ionic strength, and global protein flexibility using amide H/D exchange (HDX).

Inverse solvent isotope effects demonstrate slow aquo release from hypoxia inducible factor-prolyl hydroxylase (PHD2).

Prolyl hydroxylase domain 2 (PHD2) is deemed a primary oxygen sensor in humans, yet many details of its underlying mechanism are still not fully understood. (Fe(2+) + αKG)PHD2 is 6-coordinate, with a 2His/1Asp facial triad occupying three coordination sites, a bidentate α-ketoglutarate occupying two sites, and an aquo ligand in the final site. Turnover is thought to be initiated upon release of the aquo ligand, creating a site for O(2) to bind at the iron.