|Laboratory of Genetics (Zinder/Model)
John D. Rockefeller, Jr. Professor
This laboratory uses genetics, biochemistry, and molecular biology in an attempt to derive a complete analysis of the filamentous bacterial virus, f1, and of its interactions with its host, Escherichia coli.
The phage (and its close relatives M13 and fd) continues to provide a means for exploring bacterial DNA synthesis, translation initiation, and translocation of proteins into the bacterial membrane. It is also used for DNA cloning, since it generates single strands suitable for sequencing, probing, and easy mutagenesis. Heterologous proteins can be expressed on its surface so that it is used to detect receptors, provide antibody libraries, and clone ligands of known receptors.
Of its ten genes, five encode proteins which are part of the virus, three are required for virus-specific DNA synthesis, and two are required for assembly. Assembly of the phage is a complex, facilitated process that takes place at the cell membrane and involves both phage and host components. Extensive genetic characterization of the two assembly genes is in progress, while at the same time we are developing a system for in vitro assembly of the particle.
One of the two assembly proteins (as well as some of its homologs from other systems) induces the expression of a novel E. coli stress operon (the psp operon). This operon represents a new class of stress operon that uses a sigma factor usually employed by nitrogen-regulated genes and is itself regulated by at least three different activators and repressors. We are exploring both its complex regulation and its role in E. coli physiology.
Filamentous phage have a highly evolved translational control system, in which one of the DNA synthesis genes is regulated by another. Now that the primary specificity determining elements have been defined, we can examine how the protein recognizes its "translational operator."
Other studies relate to protein: DNA recognition, membrane anchoring, and questions of protein structure.
N. Zinder Publications