It is a locus containing a short direct repeat several present (repeat short palindrome was covered cluster regularly) CRISPRs the genome of 90% of the sequence archaea and about 40% of the sequence bacteria. In terms of imparting resistance to external elements such as plasmids and phages such immune system prokaryotic functions as a CRISPR. CRISPR system provides a form of acquired immunity. It is included in the genome between short segments of foreign DNA called spacers are repeated CRISPR, and play a role as a “memory” of past exposure. Were used to identify the exogenous genetic component in a similar manner then CRISPR spacer, and the RNAi in eukaryotes and silence. Repeat genome clustered known as CRISPR today, since the first bacteria, E. coli, and are described in 1987. In 2000, repeated a clustered similar, is called (SRSR) short regular intervals and repeat, were identified in the genome of the archaea and bacteria added. The set of genes estimation code to be associated CRISPR repetitive protein helicase or nuclease several ways has been found.
Size is 24-48 bp CRISPR is repeated. They have the following meanings dyad symmetry in the formation of secondary structure, such as the hairpin, but it is not a palindrome in practice. Is repeated CRISPR, and are separated by a spacer of similar length. Spacer some have identity of prokaryotic genome minute own (self-steering spacer), but, CRISPR sequence on the remote control of some, having a sequence identity of phage and plasmid. New spacers can be added rapidly in response to phage infection. In most cases the gene (CAS) to CRISPR-related, and is associated with CRISPR spacer multiple arrays. Residue protein family of more than 40 is disclosed. Of the protein family of these, anywhere between CRISPR / CAS system seems CAS1. (ECOLI, Ypest, Nmeni, Dvulg, Tneap, Hmari, certain combinations of CAS repeat structure and gene, and Apern 8 CRISPR subtype some of which are associated with the gene of code add related protein mystery repeat module was used for the determination of Mtube) (lamp). May occur in one genome subtype CRISPR multiple. The breakdown sporadic subtypes of CRISPR / CAS, I show that the system is subject to horizontal gene transfer in the course of evolution of microorganisms.
Foreign DNA is treated with a protein encoded by any one CRISPR associated small elements which are inserted so as to place the CRISPR leader sequence followed apparent (CAS) gene, (a ~ 30BP length). RNA from the CRISPR locus received a sequence of exogenous in repetitive sequences several adjacent that are expressed by CAS proteins small RNA consisting of individual items are processed. CA of the RNA guide other, to silence the genetic component of the exogenous protein, at the DNA level or RNA. There is evidence for the functional diversity of CRISPR between the different subtypes. CSE (CAS subtype ECOLI) proteins form a complex functional, the cascade process the RNA transcripts recurring items of the spacer, which is held (also known as Casa-E in E. coli) by cascade. In other prokaryotes, Cas6 process transcript CRISPR. Interestingly, phage inactivation of CRISPR-based, requires a CAS3 and cascade in E. coli, CAS2 and CAS1. Proteins found in prokaryotes and other Pyrococcus Julio CMR of (CAS RAMP module), to form a complex functional with small RNA CRISPR, for cutting to recognize the target RNA complementary.
Research is evolutionarily conserved CRISPRs are already showed to be a species-related cluster. Many traces of the secondary structure conservative. In order to gain immunity against specific phage by CRISPR-CAS mechanism bacteria, it is possible to stop the transmission of the phage target. For this reason, some researchers have proposed that Lamarckian inheritance mechanism CRISPR-CAS system is . Study co-evolution of other viral genome and host by analysis of CRISPR sequences.
As evidence of the demonstration of the principles of engineering selective, redirects the CRISPR-CAS system in 2012, and provided a first step toward the realization of some of the several proposals for CRISPR obtained biotechnology. By those used in large-scale fermentation and food production included, to introduce a special locus in bacteria industrially important, and artificial immunization against phage. The reprogramming of the CRISPR-CAS system, genome engineering at the organism level cell or show examples of both in vitro and in vivo this to achieve the RNA genome engineering for proof of concept study. The knockdown of endogenous gene by transformation with the CRISPR spacer region consisting of a plasmid to suppress the target gene. By comparing the sequences, determining the different bacterial strains, remote CRISPR.
Bacteria, another way can be protected from infection by phage chromosomes as islands. Subtypes islands chromosome called (PICI) island chromosomes are phage induction, can be excised from the chromosome of the bacterial phage infection, and to inhibit phage replication. To inhibit replication of the phage is not well understood yet how PICI PICI mechanism or cause ablation. Recently, however, in one study, factors such goal V. cholera PICI such that that it has acquired the ICP1 lytic phage CRISPR / CAS system target the Vibrio cholerae serotype O1 in particular revealed. Phage CRISPR / CAS system looks has a 9 CAS gene and CRISPR loci of the two, as is homologous to 1-F, which is located in Y. pestis. In addition, similar to the CRISPR / CAS system of bacteria, the ICP1 CRISPR / CAS system, phage, allowing you to be able to develop cooperation with the host, to get a new sequence.