MECHANISM OF THE LONG TAIL-FIBER DEPLOYMENT OF BACTERIOPHAGES T-EVEN AND ITS ROLE IN ADSORPTION, INFECTION AND SEDIMENTATION

Models for the tail-fiber deployment of T-even bacteriophages have bee n experimentally tested by correlating sedimentation constants, adsorp tion rates, protease inactivation kinetics, and fiber configurations o f individual phages observed by electron microscopy, Neither the colle ctive nor the individualistic model, i.e. coordinated fiber retraction and expansion or oscillation of fibers independently of each other, r espectively, could satisfactorily account for the results presented. W e propose a new intermediary model, in which the base-plate determines a collective behaviour by fixing the hinge angle, around which indivi dual fibers oscillate freely. The bidisperse, so-called dual sedimenta tion was shown to occur mainly with nascent high-concentration phage s tocks in potassium glutamate containing media. Indeed, when mature int racellular phages are released in 0.5 M potassium glutamate-a conditio n simulating the intracellular environment- only the fast form appears . Upon storage in the cold or release into 0.5 M chloride, both forms appear. Results confirming that the sedimentation constants of the fas t and slow form roughly correspond to those of the monodisperse sedime ntation, characteristic of the extreme pH values, i.e. 5 and 8, do not allow to conclude that fiber configuration is the only cause of the b idisperse sedimentation.