21-10-2014_16-13-52 / рис.4-лекц-9

Assembly of bacteriophage  virions. Empty heads and tails are assembled from multiple copies of several different  proteins. During the late stage of  infection, long DNA molecules called concatomers are formed; these multimeric molecules consist of copies of the  genome linked end to end and separated by COS sites (red), a protein-binding nucleotide sequence that occurs once in each copy of the  genome. Binding of the  proteins Nu1 and A to COS sites promotes insertion of the DNA between two adjacent COS sites into an empty head. After the heads are filled with DNA, preassembled  tails are attached, producing complete  virions capable of infecting E. coli cells.