Phage DNA transport across membranes

Phage nucleic acid transport is atypical among membrane transport and thus poses a fascinating problem: transport is unidirectional, and it concerns a unique molecule the size of which may represent 50 times that of the bacterium. The rate of DNA transport can reach values as high as 3,000 to 4,000 base pairs s(-1). This raises many questions which will be addressed in this review. Is there a single mechanism of transport for all types of phage? How does the phage genome overcome the hydrophobic barrier of the host envelope? Is DNA transported as a free molecule or in association with proteins? Is such transport dependent on phage and/or host cell components? What is the driving force for transport? Data will be presented on tailed phage which are the most common type of phage, occurring in over 100 genera of bacteria and for which DNA transport has been the most extensively studied. We will show that it is possible to analyse these mechanisms both in vivo and in vitro by using biochemical as well as biophysical approaches.