Chemical biology: Paper alert

A selection of interesting papers that were published in the two months before our press date in major journals most likely to report significant results in chemical biology.     

Lentiviral vectors

The delivery of genetic material to mammalian cells is of great importance for modern fundamental biology, biomedicine, biotechnology, agriculture, and veterinary medicine. The development of new efficient techniques of gene transfer to human cells led to the advent of gene therapy, a novel approach to treating severe metabolic disorders, some viral infections (including HIV infection), autoimmune diseases, and genetic defects causing cancer. The review considers the main principles of constructing gene transfer and expression systems based on lentiviruses, a powerful tool for human gene therapy and transgenic research, with a special focus on the genome structure and life cycle of lentiviruses and the design and safety of lentiviral vector systems.     

Structural dynamics of translating ribosomes.

We describe three groups of small angle neutron scattering (SANS) experiments with translating ribosomes: 1) regular protonated (normal abundance hydrogen) particles; 2) two isotopic hybrid particles which are reconstituted from one protonated and the other deuterated subunit; 3) four isotypic hybrid particles differing from each other by the extent of protein and RNA deuteration. Using the SANS contrast variation method the radii of gyration of protein and RNA components in both ribosomal subunits as well as the intersubunit distance in the pre- and post-translocation states were determined. The results obtained suggest the following model of the ribosome as a dynamic machine. The ribosome oscillates between two major conformers differing in geometrical dimensions. The 'active' (pulsating) part of the ribosome is the 30S subunit. We believe that the movement of its 'head' relative to the passive 50S subunit is the main mechanical act of translocation. The radius of gyration of the 30S subunit and the intersubunit distance change upon the movement. This is corroborated by neutron scattering data.