Related Experiment Video
Updated: Aug 12, 2026

Following Cell-fate in E. coli After Infection by Phage Lambda
Published on: October 14, 2011
Bacteriophage lambda DNA packaging: DNA site requirements for termination and processivity
Abstract:
Bacteriophage lambda chromosomes are processively packaged into preformed shells, using end-to-end multimers of intracellular viral DNA as the packaging substate. A 200 bp long DNA segment, cos, contains all the sequences needed for DNA packaging. The work reported here shows that efficient DNA packaging termination requires cos's I2 segment, in addition to the required termination subsite, cosQ, and the nicking site, cosN. Efficient processivity requires cosB, in addition to cosQ and cosN. An initiation-defective mutant form of cosB sponsored efficient processivity, indicating that the terminase-cosB interactions required for termination are less stringent than those required at initiation. The finding that an initiation-defective form of cosB is functional for processivity allows a re-interpretation of a similar finding, obtained previously, that the initiation-defective cosB of phage 21 is functional for processivity by the lambda packaging machinery. The cosBphi21 result can now be interpreted as indicating that interactions between cosBphi21 and lambda terminase, while insufficient for initiation, function for processivity.
Related Concept Videos
Translesion DNA Polymerases
TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...
Bacterial RNA Polymerase
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
Bacterial Transcription
Transcription can be divided into three main stages, each involving distinct DNA sequences to guide the polymerase. These are:
Transcription in Prokaryotes
Viral Replication: Lysogenic Cycle
DNA Bacteriophages

