A haem-sequestering plant peptide promotes iron uptake in symbiotic bacteria.

Symbiotic partnerships with rhizobial bacteria enable legumes to grow without nitrogen fertilizer because rhizobia convert atmospheric nitrogen gas into ammonia via nitrogenase. After Sinorhizobium meliloti penetrate the root nodules that they have elicited in Medicago truncatula, the plant produces a family of about 700 nodule cysteine-rich (NCR) peptides that guide the differentiation of endocytosed bacteria into nitrogen-fixing bacteroids. The sequences of the NCR peptides are related to the defensin class of antimicrobial peptides, but have been adapted to play symbiotic roles.

Kinetic and structural evidence that Asp-678 plays multiple roles in catalysis by the quinoprotein glycine oxidase.

PlGoxA from is a glycine oxidase that utilizes a protein-derived cysteine tryptophylquinone (CTQ) cofactor. A notable feature of its catalytic mechanism is that it forms a stable product-reduced CTQ adduct that is not hydrolyzed in the absence of O Asp-678 resides near the quinone moiety of PlGoxA, and an Asp is structurally conserved in this position in all tryptophylquinone enzymes. In those other enzymes, mutation of that Asp results in no or negligible CTQ formation.

Structural and Spectroscopic Characterization of a Product Schiff Base Intermediate in the Reaction of the Quinoprotein Glycine Oxidase, GoxA.

The LodA-like proteins make up a recently identified family of enzymes that rely on a cysteine tryptophylquinone cofactor for catalysis. They differ from other tryptophylquinone enzymes in that they are oxidases rather than dehydrogenases. GoxA is a member of this family that catalyzes the oxidative deamination of glycine.

Structure and Enzymatic Properties of an Unusual Cysteine Tryptophylquinone-Dependent Glycine Oxidase from Pseudoalteromonas luteoviolacea.

Glycine oxidase from Pseudoalteromonas luteoviolacea (PlGoxA) is a cysteine tryptophylquinone (CTQ)-dependent enzyme. Sequence analysis and phylogenetic analysis place it in a newly designated subgroup (group IID) of a recently identified family of LodA-like proteins, which are predicted to possess CTQ. The crystal structure of PlGoxA reveals that it is a homotetramer.

Mechanisms of zinc binding to the solute-binding protein AztC and transfer from the metallochaperone AztD.

Bacteria can acquire the essential metal zinc from extremely zinc-limited environments by using ATP-binding cassette (ABC) transporters. These transporters are critical virulence factors, relying on specific and high-affinity binding of zinc by a periplasmic solute-binding protein (SBP). As such, the mechanisms of zinc binding and release among bacterial SBPs are of considerable interest as antibacterial drug targets.