Ff-nano, Short Functionalized Nanorods Derived from Ff (f1, fd or M13) Filamentous Bacteriophage

Abstract

F-specific filamentous phage of Escherichia coli (Ff: f1, M13 or fd) are long thin filaments (860 nm x 6 nm). They have been a major workhorse in display technologies and bionanotechnology; however, some applications are limited by the high length-to-diameter ratio of Ff. Furthermore, use of functionalized Ff outside of laboratory containment is in part hampered by the fact that they are genetically modified viruses. We have now developed a system for production and purification of very short functionalized Ff-phage-derived nanorods, named Ff-nano, that are only 50 nm in length. In contrast to standard Ff-derived vectors that replicate in E. coli and contain antibiotic-resistance genes, Ff-nano are protein-DNA complexes that cannot replicate on their own and do not contain any coding sequences. These nanorods show an increased resistance to heating at 70 °C in 1 % SDS in comparison to the full-length Ff phage of the same coat composition. We demonstrate that functionalized Ff-nano particles are suitable for application as detection particles in sensitive and quantitative "dipstick" lateral flow diagnostic assay for human plasma fibronectin.

Cryo-electron microscopy of the f1 filamentous phage reveals a new paradigm in viral infection and assembly

“…The design of this cassette that includes the (-) ori allows replication of both strands once the ssDNA has been excised. This in turn results in an increased nanorod production in comparison to the previously reported nanorod template plasmids containing only the (+) ori that allows only the positive strand replication from the template plasmid 32,73,74 Top: input f1d3 phage stock carrying a complete deletion of gIII from the genome. Full-length pIII in the phage coat is supplied in trans from a plasmid.…”

“…To overcome this, we generated a short version of Ff. This is possible because the length of Ffs can be modulated by changing the size of the packaged DNA 32 . We developed a phage-free plasmid-based system that enables a short version of Ff to be produced based on f1 phage.…”