Single-stranded Filamentous DNA Bacteriophages M13, fI and fd Distinct Properties of M13 Infect Escherichia coli Infect only male cells through attachment to the male-specific pilus Have circular single-stranded dnA Can be used as a cloning vector and dnA sequencing vehicle in genetic engineering Infect but not kill the cells
Single-Stranded Filamentous DNA Bacteriophages M13, f1 and fd Distinct Properties of M13 – Infect Escherichia coli – Infect only male cells through attachment to the male-specific pilus – Have circular single-stranded DNA – Can be used as a cloning vector and DNA sequencing vehicle in genetic engineering – Infect but not kill the cells
M13 leaves an infected cell without lysis Cytoplasmic memb Cell Coat proteins embedded in cytoplasmic membrane 00 e dNA A-protein ss circle C-p Environment Cytoplasm
M13 leaves an infected cell without lysis
Double-Stranded DNA Bacteriophage: the first discovered phage and the most extensively studied ds dna viruses. Example: T7 1. Linear double-stranded DNA with 39,936 base pairs 2.92% DNA codes for protein 3. Gene overlap through translation in different reading frame and through internal translational reinitiation as well as internal frame shifts 4. One of the coded proteins inhibits the host restriction system, it is synthesized before the entire t7 genome enters the cells
Double-Stranded DNA Bacteriophage: the first discovered phage and the most extensively studied ds DNA viruses. Example: T7 1. Linear double-stranded DNA with 39,936 base pairs 2. 92% DNA codes for protein 3. Gene overlap through translation in different reading frame and through internal translational reinitiation as well as internal frame shifts. 4. One of the coded proteins inhibits the host restriction system, it is synthesized before the entire T7 genome enters the cells
Left end Earty promoters Overcomes host restriction Protein kinase Genetic Early transcript RNA polymerase 1.1 Unknown Origin of DNA replication Map of T7 DNA lease 1.7 Nonessential Inactivate host RNA polymeraseProteins Early transcription occurs Endonuclease 3.5 Lysozyme for DNA replication when left end enters cells Helicase, pr and host lysis DNA polymerase A host rna polymerase Protein in phage part is used just to copy the Head prot first few genes and to 9 Head assembly prot make the mrNa that Tail protein codes for the phage- Tail protein specific rna polymerase Protein in phage partick 14 Head protein structural Head protein and Two other early mrnA maturation 16 code for proteins which stop the action of host RNa polymerase DNA m
Genetic Map of T7 Early transcription occurs when left end enters cells A host RNA polymerase is used just to copy the first few genes and to make the mRNA that codes for the phagespecific RNA polymerase Two other early mRNA code for proteins which stop the action of host RNA polymerase
DNA Replication in T7 Origin of In both direction. an RNa primer is involved Rightward: RNA primer is synthesized by T7 Eye"form 5 RNa polymerase Leftward: RNa primer is "Y form synthesized by primase Both primers are elongated by T7 DNA polymerase Completed strands
DNA Replication in T7 In both direction, an RNA primer is involved. Rightward: RNA primer is synthesized by T7 RNA polymerase Leftward: RNA primer is synthesized by T7 primase Both primers are elongated by T7 DNA polymerase