What does the CRO protein do?
Cro, a repressor protein of temperate bacteriophages (e.g. lambda [l], 434, P22), works in opposition to the phage’s repressor to control the genetic switch that determines whether a lytic or lysogenic cycle will follow infection.
How does CRO bind to DNA?
Lambda Cro The momomer of Cro from bacteriophage Lambda consists of 66 amino acids and contains three alpha helices and three beta strands. The latter helix of each is termed the recognition alpha helix and binds to the DNA by insertion into the major groove.
What is the function of the Cro protein in the lambda phage operon?
Cro dominates the repressor site (see “Repressor” section), repressing synthesis from the PRM promoter (which is a promoter of the lysogenic cycle). The O and P proteins initiate replication of the phage chromosome (see “Lytic Replication”).
What is the role of phage cI gene?
The cI repressor protein inhibits the lytic development of any additional infecting phage particles. The region of the genome that codes for the cI repressor protein is known as the immunity region.
Is Cro lytic or lysogenic?
The lysogenic state of bacteriophage λ is exceptionally stable yet the prophage is readily induced in response to DNA damage. This delicate epigenetic switch is believed to be regulated by two proteins; the lysogenic maintenance promoting protein CI and the early lytic protein Cro.
What is the difference between Lysogenic cycle and lytic cycle?
The lytic cycle involves the reproduction of viruses using a host cell to manufacture more viruses; the viruses then burst out of the cell. The lysogenic cycle involves the incorporation of the viral genome into the host cell genome, infecting it from within.
How the Cro protein Recognises the specific DNA sequence?
Proteins recognize a particular sequence by having a surface that is chemically complementary to that of the DNA, forming a series of favorable electrostatic and van der Waals interactions between the protein and the base pairs.
Why is bacteriophage lambda important?
Lambda phage has been of major importance in the study of specialized transduction. Specialized transduction is the process by which a restricted set of bacterial genes are transferred to another bacterium. The genes that get transferred (donor genes) depend on where the phage genome is located on the chromosome.
What does bacteriophage lambda cause?
Bacteriophage lambda is a virus that infects E. coli. The typical infection cycle results in the lysis of the E. coli cell and the release of about 100 progeny phage particles, each capable of infecting another cell.
How does bacteriophage reproduce?
Bacteriophages, just like other viruses, must infect a host cell in order to reproduce. The steps that make up the infection process are collectively called the lifecycle of the phage. Some phages can only reproduce via a lytic lifecycle, in which they burst and kill their host cells.
Is lambda cro a transcription factor?
We transfer this activating patch onto the surface of lambda Cro, a protein normally unable to activate transcription, and show that the modified Cro is a transcriptional activator.
What is lytic cycle of bacteriophage?
The lytic cycle, which is also referred to as the “reproductive cycle” of the bacteriophage, is a six-stage cycle. The six stages are: attachment, penetration, transcription, biosynthesis, maturation, and lysis.
