Transcriptional Regulation, Metal Binding Properties and Structure of Pden1597, an Unusual Zinc Transport Protein from Paracoccus denitrificans
Year: 2015
Type: article
Abstract: ATP-binding cassette (ABC) transporters of the cluster 9 family are ubiquitous among bacteria and essential for acquiring Zn 2+ and Mn 2+ from the environment or, in the case of pathogens, from the host. These rely on a substrate-binding protein (SBP) to coordinate the relevant metal with high affinity and specificity and subsequently release it to a membrane permease for translocation into the cytoplasm. Although a number of cluster 9 SBP structures have been determined, the structural attributes conferring Zn 2+ or Mn 2+ specificity remain ambiguous. Here we describe the gene expression profile, in vitro metal binding properties, and crystal structure of a new cluster 9 SBP from Paracoccus denitrificans we have called AztC. Although all of our results strongly indicate Zn 2+ over Mn 2+ specificity, the Zn 2+ ion is coordinated by a conserved Asp residue only observed to date as a metal ligand in Mn 2+ -specific SBPs. The unusual sequence properties of this protein are shared among close homologues, including members from the human pathogens Klebsiella pneumonia and Enterobacter aerogenes , and would seem to suggest a subclass of Zn 2+ -specific transporters among the cluster 9 family. In any case, the unusual coordination environment of AztC expands the already considerable range of those available to Zn 2+ -specific SBPs and highlights the presence of a His-rich loop as the most reliable indicator of Zn 2+ specificity. Background: Bacterial cluster 9 ATP binding cassette (ABC) transporters are responsible for import of Zn 2+ and Mn 2+ . Results: A solute-binding protein of the cluster 9 family is shown to preferentially bind Zn 2+ in an unusual coordination sphere. Conclusion: A subclass of Zn 2+ transporter has been identified with distinct structural properties. Significance: Cluster 9 ABC transporters are important virulence factors.
Source: Journal of Biological Chemistry
Authors: Melody Handali, Durga P. Neupane, Hridindu Roychowdhury, Erik T. Yukl
Institution: New Mexico State University
Language: English
Subfield: Oncology
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W1999123993