Cu(I) recognition via cation-pi and methionine interactions in CusF.

Methionine-rich motifs have an important role in copper trafficking factors, including the CusF protein. Here we show that CusF uses a new metal recognition site wherein Cu(I) is tetragonally displaced from a Met2His ligand plane toward a conserved tryptophan. Spectroscopic studies demonstrate that both thioether ligation and strong cation-pi interactions with tryptophan stabilize metal binding.

A multinuclear copper(I) cluster forms the dimerization interface in copper-loaded human copper chaperone for superoxide dismutase.

Copper binding and X-ray aborption spectroscopy studies are reported on untagged human CCS (hCCS; CCS = copper chaperone for superoxide dismutase) isolated using an intein self-cleaving vector and on single and double Cys to Ala mutants of the hCCS MTCQSC and CSC motifs of domains 1 (D1) and 3 (D3), respectively. The results on the wild-type protein confirmed earlier findings on the CCS-MBP (maltose binding protein) constructs, namely, that Cu(I) coordinates to the CXC motif, forming a cluster at the interface of two D3 polypeptides. In contrast to the single Cys to Ser mutations of the CCS-MBP protein (Stasser, J.

Cysteine-to-serine mutants of the human copper chaperone for superoxide dismutase reveal a copper cluster at a domain III dimer interface.

Cysteine-to-serine mutants of a maltose binding protein fusion with the human copper chaperone for superoxide dismutase (hCCS) were studied with respect to (i) their ability to transfer Cu to E,Zn superoxide dismutase (SOD) and (ii) their Zn and Cu binding and X-ray absorption spectroscopic (XAS) properties. Previous work has established that Cu(I) binds to four cysteine residues, two of which, C22 and C25, reside within an Atox1-like N-terminal domain (DI) and two of which, C244 and C246, reside in a short unstructured polypeptide chain at the C-terminus (DIII). The wild-type (WT) protein shows an extended X-ray absorption fine structure (EXAFS) spectrum characteristic of cluster formation, but it is not known how such a cluster is formed.

SpaC and NisC, the cyclases involved in subtilin and nisin biosynthesis, are zinc proteins.

Lantibiotics are peptide-derived antimicrobial agents that are ribosomally synthesized and posttranslationally modified by a multienzyme complex to their biologically active forms. Nisin has attracted much attention recently due to its novel mechanism of action including specific binding to the bacterial cell wall precursor lipid II, followed by membrane permeabilization. Nisin has been commercially used as a food preservative, while other lantibiotics show promising activity against bacterial infections.