NEW YORK (Reuters Health) - By identifying bacteriophage-encoded polypeptides and their cognate bacterial target proteins, scientists have a promising new means of designing novel antimicrobial agents, according to a report in Nature Biotechnology published online January 11.
“Our objective is to identify new classes of antibiotic against novel targets, especially for treatment of resistant bacterial strains,” senior investigator Dr. Jinzi J. Wu told Reuters Health. To that end, he and his team identified phage polypeptides to “fish out bacterial targets,” he explained, then screened for small molecules that could block the phage protein-S. aureus interaction.
Dr. Wu, at PhageTech Inc. in Ville Saint Laurent, Quebec and colleagues there and at McGill University in Montreal sequenced 26 Staphylococcus aureus phages and identified 31 novel polypeptide families that inhibited growth when expressed within the host cell.
In some cases, dissimilar polypeptides from different phages targeted the same bacterial proteins, “underscoring the particular susceptibility of these proteins to inhibition and their suitability for antimicrobial drug discovery,” the investigators write.
The authors screened 69 predicted open reading frames (ORFs) in phage 77 and identified three new ORFs that inhibited S. aureus growth. Out of the 895 ORFs from 26 other phages, they identified 31 distinct families of growth-inhibitory proteins.
Several different assays confirmed that the 104 ORF of phage 77 directly interacted with S. aureus Dna1, a molecule they subsequently found to be essential for host viability.
Moreover, when they screened 125,000 small-molecule compounds for inhibition of the 77ORF104 - Dna1 interaction, 11 had a minimum inhibitory concentration of 16 µg/mL or less against S. aureus. Two of these compounds, upon closer examination, were not cytotoxic to human primary hepatocytes or to two established cell lines.
Since submission of their paper, Dr. Wu noted that his team has used this new technology to identify “some interesting targets for Pseudomonas aeruginosa,” as well as targets in streptococci with sequence homology to staphylococcal targets. They already have one US patent, and have submitted an application for an “umbrella patent” to cover their technology platform, he added.
Source: Nat Biotechnol 2004.doi:10.1038/nbt932 [ Google search on this article ]
MeSH Headings:Biological Phenomena: Biological Phenomena, Cell Phenomena, and Immunity: Biological Sciences: Biology: Drug Resistance, Microbial: Genetics: Genetics, Microbial: Microbiologic Phenomena: Pharmacogenetics: Staphylococcus Phages: Drugs, Investigational: Biological SciencesCopyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
