MSU & SkolTech Restriction/modification Restriction/modification Restriction endonucleases cleave

Restriction/modification Restriction endonucleases cleave DNA at specific sites

Restriction/modification Methyltransferases methylate specific DNA sites thus preventing DNA cleavage by restriction endonucleases

Restriction/modification Restriction/modification protects bacteria from phage attacks

Restriction/modification Methylation is maintained through cell divisions, permanently protecting host DNA from cleavage

Restriction/modification R/E systems could also be considered as selfish elements, since they kills bacteria,

Restriction/modification Restriction endonuclease types

Restriction/modification Methyltransferases utilize SAM as a methyl group donor

Restriction/modification Methyltransferases usually contains conserved catalytic domain and variable recognition domain

Restriction/modification C-methyltransferases use a stepwise mechanism via covalent intermediate

Restriction/modification Regulation of R/E systems

Restriction/modification Regulation of CfrBI Before DNA methylation After DNA methylation

Restriction/modification Regulation of SsoII Before C protein Medium level of C protein Excess of

Restriction/modification Homing endonucleases

Restriction/modification Restriction endonuclease genes as mobile elements?

Restriction/modification Phage defense against restriction

CRISPR CRISPR (clustered regularly interspaced short palindromic repeats)-associated system (CRISPR-Cas) Spacers contains sequences from

Expression of CRISPR/Cas locus lead to the formation of defence complex Cascade CRISPR

Cascade recognize and cleaves invader DNA that match crRNA CRISPR

Cascade recognizes and cleaves target DNA CRISPR

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2-8._restriction_modification.ppt

Количество слайдов: 23

>MSU & SkolTech Restriction/modification MSU & SkolTech Restriction/modification

>Restriction/modification Restriction endonucleases cleave DNA at specific sites Restriction/modification Restriction endonucleases cleave DNA at specific sites

>Restriction/modification Methyltransferases methylate specific DNA sites thus preventing DNA cleavage by restriction endonucleases Restriction/modification Methyltransferases methylate specific DNA sites thus preventing DNA cleavage by restriction endonucleases

>Restriction/modification Restriction/modification protects bacteria from phage attacks Restriction/modification Restriction/modification protects bacteria from phage attacks

>Restriction/modification Methylation is maintained through cell divisions, permanently protecting host DNA from cleavage Restriction/modification Methylation is maintained through cell divisions, permanently protecting host DNA from cleavage

>Restriction/modification R/E systems could also be considered as selfish elements, since they kills bacteria, Restriction/modification R/E systems could also be considered as selfish elements, since they kills bacteria, which lost the corresponding genes

>Restriction/modification Restriction endonuclease types Restriction/modification Restriction endonuclease types

>Restriction/modification Methyltransferases utilize SAM as a methyl group donor Restriction/modification Methyltransferases utilize SAM as a methyl group donor

>Restriction/modification Methyltransferases usually contains conserved catalytic domain and variable recognition domain Restriction/modification Methyltransferases usually contains conserved catalytic domain and variable recognition domain

>Restriction/modification C-methyltransferases use a stepwise mechanism via covalent intermediate Restriction/modification C-methyltransferases use a stepwise mechanism via covalent intermediate

>Restriction/modification Regulation of R/E systems Restriction/modification Regulation of R/E systems Aims of regulation 1. Methyltransferase should appear first to protect host DNA 2. Restriction nuclease expression should follow that of methyltransferase 3. In a steady state methyltransferase shouldn’t be in a too much excess (not to methylate phage DNA)

>Restriction/modification Regulation of CfrBI Before DNA methylation After DNA methylation Restriction/modification Regulation of CfrBI Before DNA methylation After DNA methylation

>Restriction/modification Regulation of SsoII Before C protein Medium level of C protein Excess of Restriction/modification Regulation of SsoII Before C protein Medium level of C protein Excess of C protein

>Restriction/modification Homing endonucleases Restriction/modification Homing endonucleases

>Restriction/modification Meganucleases Restriction/modification Meganucleases

>Restriction/modification Restriction endonuclease genes as mobile elements? Restriction/modification Restriction endonuclease genes as mobile elements?

>Restriction/modification Phage defense against restriction Restriction/modification Phage defense against restriction

>CRISPR CRISPR (clustered regularly interspaced short palindromic repeats)-associated system (CRISPR-Cas) Spacers contains sequences from CRISPR CRISPR (clustered regularly interspaced short palindromic repeats)-associated system (CRISPR-Cas) Spacers contains sequences from phage and plasmids Acquisition of a spacer makes cell resistant to the phage containing the corresponding DNA

>Expression of CRISPR/Cas locus lead to the formation of defence complex Cascade CRISPR Expression of CRISPR/Cas locus lead to the formation of defence complex Cascade CRISPR

>Cascade recognize and cleaves invader DNA that match crRNA CRISPR Cascade recognize and cleaves invader DNA that match crRNA CRISPR

>Cascade recognizes and cleaves target DNA CRISPR Cascade recognizes and cleaves target DNA CRISPR