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14  structures 628  species 0  interactions 667  sequences 2  architectures

Family: CRISPR_assoc (PF08798)

Summary: CRISPR associated protein

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CRISPR Edit Wikipedia article

Diagram of the possible mechanism for CRISPR.[1]

CRISPRs (Clustered Regularly Interspaced Short Palindromic Repeats) are loci containing multiple short direct repeats that are found in the genomes of approximately 40% of sequenced bacteria and 90% of sequenced archaea.[2][3] CRISPR functions as a prokaryotic immune system, in that it confers resistance to exogenous genetic elements such as plasmids and phages.[4][5] The CRISPR system provides a form of acquired immunity. Short segments of foreign DNA, called spacers, are incorporated into the genome between CRISPR repeats, and serve as a 'memory' of past exposures.[6] CRISPR spacers are then used to recognize and silence exogenous genetic elements in a manner analogous to RNAi in eukaryotic organisms.[6]

Contents

Discovery of CRISPR [edit]

The clustered genomic repeats that are today known as CRISPR were first described in 1987 for the bacterium Escherichia coli.[7] In 2000, similar clustered repeats were identified in the genomes of additional bacteria and archaea, and were termed Short Regularly Spaced Repeats (SRSR).[8] SRSR were renamed CRISPR in 2002.[9] A set of genes, some encoding putative nuclease or helicase proteins, were found to be associated with CRISPR repeats (the cas, or CRISPR-associated, genes).[9]

Simplified diagram of a CRISPR locus. The three major components of a CRISPR locus are shown: cas genes, a leader sequence, and a repeat-spacer array. Repeats are shown as grey boxes and spacers are colored bars. While most CRISPR loci contain each of the three components, the arrangement is not always as shown.[1][6]

CRISPR locus structure [edit]

CRISPR repeats and spacers [edit]

CRISPR repeats range in size from 24 to 48 base pairs.[10] They usually show some dyad symmetry, implying the formation of a secondary structure such as a hairpin, but are not truly palindromic.[11] CRISPR repeats are separated by spacers of similar length.[10] Some CRISPR spacer sequences have identity to sequences from plasmids and phage,[12][13][14] although some spacers have identity to the prokaryote's own genome (self-targeting spacers).[15] New spacers can be added rapidly in response to phage infection.[16]

cas genes and CRISPR subtypes [edit]

The CRISPR-associated (cas) genes are often associated with CRISPR repeat-spacer arrays. More than forty different Cas protein families have been described.[10] Of these protein families, Cas1 appears to be ubiquitous among different CRISPR/Cas systems. Particular combinations of cas genes and repeat structures have been used to define 8 CRISPR subtypes (Ecoli, Ypest, Nmeni, Dvulg, Tneap, Hmari, Apern, and Mtube), some of which are associated with an additional gene module encoding repeat-associated mysterious proteins (RAMPs).[10] More than one CRISPR subtype may occur in a single genome. The sporadic distribution of the CRISPR/Cas subtypes suggests that the system is subject to horizontal gene transfer during microbial evolution.

CRISPR associated protein
PDB 1wj9 EBI.jpg
crystal structure of a crispr-associated protein from thermus thermophilus
Identifiers
Symbol CRISPR_assoc
Pfam PF08798
Pfam clan CL0362
InterPro IPR010179
CDD cd09727
CRISPR associated protein Cas2
PDB 1zpw EBI.jpg
crystal structure of a hypothetical protein tt1823 from thermus thermophilus
Identifiers
Symbol CRISPR_Cas2
Pfam PF09827
InterPro IPR019199
CDD cd09638
CRISPR-associated protein Cse1
Identifiers
Symbol CRISPR_Cse1
Pfam PF09481
InterPro IPR013381
CDD cd09729
CRISPR-associated protein Cse2
Identifiers
Symbol CRISPR_Cse2
Pfam PF09485
InterPro IPR013382
CDD cd09670

CRISPR mechanism [edit]

Exogenous DNA is apparently processed by proteins encoded by some of the CRISPR-associated (cas) genes into small elements (of ~30bp in length), which are then somehow inserted into the CRISPR locus near the leader sequence. RNAs from the CRISPR loci are constitutively expressed and are processed by Cas proteins to small RNAs composed of individual exogenously derived sequence elements with some flanking repeat sequence. The RNAs guide other Cas proteins to silence exogenous genetic elements at the RNA or DNA level.[1][17] There is evidence for functional diversity among the different CRISPR subtypes. The Cse (Cas subtype Ecoli) proteins (called CasA-E in E. coli) form a functional complex, Cascade, that processes CRISPR RNA transcripts into spacer-repeat units that are retained by Cascade.[18] In other prokaryotes, Cas6 processes the CRISPR transcripts. Interestingly, CRISPR-based phage inactivation in E. coli requires Cascade and Cas3, but not Cas1 and Cas2. The Cmr (Cas RAMP module) proteins found in Pyrococcus furiosus and other prokaryotes form a functional complex with small CRISPR RNAs that recognizes and cleaves complementary target RNAs.

Evolutionary significance and possible applications [edit]

A bioinformatic study has shown that the CRISPRs are evolutionarily conserved and cluster into related types. Many show signs of a conserved secondary structure.[11]

Through the CRISPR-Cas mechanism bacteria can acquire immunity against certain phages and thus halt further transmission of targeted phages. For this reason, some researchers have proposed that the CRISPR-Cas system is a Lamarckian inheritance mechanism.[19] Others investigated the coevolution of host and viral genomes by analysis of CRISPR sequences.[20]

The proof-of-principle demonstration of selective engineered redirection of the CRISPR-Cas system in 2012[21] provided a first step toward realization of some of the several proposals for CRISPR-derived biotechnology:[22]

  • Artificial immunization against phage by introduction of engineered CRISPR loci in industrially important bacteria, including those used in food production and large-scale fermentations.
  • Genome engineering at cellular or organismic level by reprogramming of a CRISPR-Cas system to achieve RNA-guided genome engineering, proof of concept studies has demonstrated examples on this front both in vitro and in vivo.[23][24][25][26]
  • Knockdown of endogenous genes by transformation with a plasmid which contains a CRISPR area with a spacer, which inhibits a target gene.
  • Discrimination of different bacterial strains by comparison of CRISPR spacer sequences (spoligotyping).

References [edit]

  1. ^ a b c Horvath P, Barrangou R (January 2010). "CRISPR/Cas, the immune system of bacteria and archaea". Science 327 (5962): 167–70. doi:10.1126/science.1179555. PMID 20056882. 
  2. ^ 71/79 Archaea, 463/1008 Bacteria CRISPRdb, Date: 19.6.2010
  3. ^ Grissa I, Vergnaud G, Pourcel C (2007). "The CRISPRdb database and tools to display CRISPRs and to generate dictionaries of spacers and repeats". BMC Bioinformatics 8: 172. doi:10.1186/1471-2105-8-172. PMC 1892036. PMID 17521438. 
  4. ^ Barrangou R, Fremaux C, Deveau H, et al. (March 2007). "CRISPR provides acquired resistance against viruses in prokaryotes". Science 315 (5819): 1709–12. doi:10.1126/science.1138140. PMID 17379808. 
  5. ^ Marraffini LA, Sontheimer EJ (December 2008). "CRISPR Interference Limits Horizontal Gene Transfer in Staphylococci by Targeting DNA". Science 322 (5909): 1843–5. doi:10.1126/science.1165771. PMC 2695655. PMID 19095942. 
  6. ^ a b c Marraffini LA, Sontheimer EJ (February 2010). "CRISPR interference: RNA-directed adaptive immunity in bacteria and archaea". Nat Rev Genet 11 (3): 181–190. doi:10.1038/nrg2749. PMC 2928866. PMID 20125085. 
  7. ^ Ishino Y, Shinagawa H, Makino K, Amemura M, Nakata A (1987). "Nucleotide sequence of the iap gene, responsible for alkaline phosphatase isozyme conversion in Escherichia coli, and identification of the gene product". J Bacteriol 169 (12): 5429–33. PMC 213968. PMID 3316184. 
  8. ^ Mojica FJM, Díez-Villaseñor C, Soria E, Juez G (2000). "Biological significance of a family of regularly spaced repeats in the genomes of Archaea, Bacteria and mitochondria". Mol Microbiol 36 (1): 244–6. doi:10.1046/j.1365-2958.2000.01838.x. PMID 10760181. 
  9. ^ a b Jansen R, Embden JD, Gaastra W, Schouls LM (2002). "Identification of genes that are associated with DNA repeats in prokaryotes". Mol Microbiol 43 (6): 1565–75. doi:10.1046/j.1365-2958.2002.02839.x. PMID 11952905. 
  10. ^ a b c d Haft DH, Selengut J, Mongodin EF, Nelson KE (2005). "A Guild of 45 CRISPR-Associated (Cas) Protein Families and Multiple CRISPR/Cas Subtypes Exist in Prokaryotic Genomes". PLoS Comput Biol. 1 (6): e60. doi:10.1371/journal.pcbi.0010060. PMC 1282333. PMID 16292354. 
  11. ^ a b Kunin V, Sorek R, Hugenholtz P (2007). "Evolutionary conservation of sequence and secondary structures in CRISPR repeats". Genome Biol 8 (4): R61. doi:10.1186/gb-2007-8-4-r61. PMC 1896005. PMID 17442114. 
  12. ^ Mojica FJ, Díez-Villaseñor C, García-Martínez J, Soria E (February 2005). "Intervening sequences of regularly spaced prokaryotic repeats derive from foreign genetic elements". J. Mol. Evol. 60 (2): 174–82. doi:10.1007/s00239-004-0046-3. PMID 15791728. 
  13. ^ Bolotin A, Quinquis B, Sorokin A, Ehrlich SD (August 2005). "Clustered regularly interspaced short palindrome repeats (CRISPRs) have spacers of extrachromosomal origin". Microbiology (Reading, Engl.) 151 (Pt 8): 2551–61. doi:10.1099/mic.0.28048-0. PMID 16079334. 
  14. ^ Pourcel C, Salvignol G, Vergnaud G (2005). "CRISPR elements in Yersinia pestis acquire new repeats by preferential uptake of bacteriophage DNA, and provide additional tools for evolutionary studies". Microbiology 151 (Pt 3): 653–63. doi:10.1099/mic.0.27437-0. PMID 15758212. 
  15. ^ Stern A, Keren L, Wurtzel O, Amitai G, Sorek R (August 2010). "Self-targeting by CRISPR: gene regulation or autoimmunity?". Trends Genet. 26 (8): 335–40. doi:10.1016/j.tig.2010.05.008. PMC 2910793. PMID 20598393. 
  16. ^ Tyson GW, Banfield JF (January 2008). "Rapidly evolving CRISPRs implicated in acquired resistance of microorganisms to viruses". Environ. Microbiol. 10 (1): 200–7. doi:10.1111/j.1462-2920.2007.01444.x. PMID 17894817. 
  17. ^ Makarova KS, Grishin NV, Shabalina SA, Wolf YI, Koonin EV (2006). "A putative RNA-interference-based immune system in prokaryotes: computational analysis of the predicted enzymatic machinery, functional analogies with eukaryotic RNAi, and hypothetical mechanisms of action". Biol Direct 1: 7. doi:10.1186/1745-6150-1-7. PMC 1462988. PMID 16545108. 
  18. ^ Brouns SJ, Jore MM, Lundgren M, et al. (August 2008). "Small CRISPR RNAs guide antiviral defense in prokaryotes". Science 321 (5891): 960–4. doi:10.1126/science.1159689. PMID 18703739. 
  19. ^ Koonin EV, Wolf YI (2009). "Is evolution Darwinian or/and Lamarckian?". Biol Direct 4: 42. doi:10.1186/1745-6150-4-42. PMC 2781790. PMID 19906303. 
  20. ^ Heidelberg JF, Nelson WC, Schoenfeld T, Bhaya D (2009). "Germ Warfare in a Microbial Mat Community: CRISPRs Provide Insights into the Co-Evolution of Host and Viral Genomes". In Ahmed, Niyaz. PLoS ONE 4 (1): e4169. doi:10.1371/journal.pone.0004169. PMC 2612747. PMID 19132092. 
  21. ^ Hale, Caryn R.; Majumdar, Sonali; Elmore, Joshua; Pfister, Neil; Compton, Mark; Olson, Sara; Resch, Alissa M.; Glover, Claiborne V.C.; Graveley, Brenton R.; Terns, Rebecca M.; Terns, Michael P. (5 Jan 2012), "Essential Features and Rational Design of CRISPR RNAs that Function with the Cas RAMP Module Complex to Cleave RNAs", Molecular Cell, New Articles (preprints), doi:10.1016/j.molcel.2011.10.023, retrieved 6 Jan 2012 
  22. ^ Sorek R, Kunin V, Hugenholtz P (2008). "CRISPR--a widespread system that provides acquired resistance against phages in bacteria and archaea". Nat Rev Microbiol 6 (3): 181–6. doi:10.1038/nrmicro1793. PMID 18157154. 
  23. ^ Jinek, M; Chylinski K, Fonfara I, Hauer M, Doudna JA, Charpentier E. (2012). "A programmable dual-RNA-guided DNA endonuclease in adaptive bacterial immunity". Science. PMID 22745249. 
  24. ^ Cong, Le; Ran FA, Cox D, Lin S, Barretto R, Habib N, Hsu PD, Wu X, Jiang W, Marraffini LA, Zhang F. (2013). "Multiplex genome engineering using CRISPR/Cas systems.". Science. PMID 23287718. 
  25. ^ Mali, P; Yang L, Esvelt KM, Aach J, Guell M, DiCarlo JE, Norville JE, Church GM. (2013). "RNA-guided human genome engineering via Cas9.". Science. PMID 23287722. 
  26. ^ Cong, Le; Wang H, Yang H, Shivalila CS, Dawlaty MM, Cheng AW, Zhang F, Jaenisch R. (2013). "One-Step Generation of Mice Carrying Mutations in Multiple Genes by CRISPR/Cas-Mediated Genome Engineering.". Cell. PMID 23643243. 

Further reading [edit]

External links [edit]

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

CRISPR associated protein Provide feedback

This domain forms an anti-parallel beta strand structure with flanking alpha helical regions.

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR010179

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) are a family of DNA direct repeats separated by regularly sized non-repetitive spacer sequences that are found in most bacterial and archaeal genomes [PUBMED:17442114]. CRISPRs appear to provide acquired resistance against bacteriophages, possibly acting with an RNA interference-like mechanism to inhibit gene functions of invasive DNA elements [PUBMED:17379808, PUBMED:16545108]. Differences in the number and type of spacers between CRISPR repeats correlate with phage sensitivity. It is thought that following phage infection, bacteria integrate new spacers derived from phage genomic sequences, and that the removal or addition of particular spacers modifies the phage-resistance phenotype of the cell. Therefore, the specificity of CRISPRs may be determined by spacer-phage sequence similarity.

In addition, there are many protein families known as CRISPR-associated sequences (Cas), which are encoded in the vicinity of CRISPR loci [PUBMED:16292354]. CRISPR/cas gene regions can be quite large, with up to 20 different, tandem-arranged cas genes next to a CRISPR cluster or filling the region between two repeat clusters. Cas genes and CRISPRs are found on mobile genetic elements such as plasmids, and have undergone extensive horizontal transfer. Cas proteins are thought to be involved in the propagation and functioning of CRISPRs. Some Cas proteins show similarity to helicases and repair proteins, although the functions of most are unknown. Cas families can be divided into subtypes according to operon organisation and phylogeny.

This entry represents the Cse3 (CRISPR/Cas Subtype Ecoli protein 3) family of Cas proteins. The Thermus thermophilus HB8 family member has been crystallised and found to have a structure consisting of two domains with opposing parallel beta-sheets, known as a beta-sheet platform [PUBMED:16672237]. This structure is similar to those found in the sex-lethal protein and poly(A)-binding protein and is consistent with an RNA-binding function.

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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Pfam Clan

This family is a member of clan RAMPS-Cas5-like (CL0362), which contains the following 7 members:

Cas6 Cas_Cas5d Cas_Cas6 Cas_Cmr3 CRISPR_assoc DUF2276 RAMPs

Alignments

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  Seed
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Full
(667)
Representative proteomes NCBI
(457)
Meta
(17)
RP15
(39)
RP35
(99)
RP55
(117)
RP75
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  Seed
(50)
Full
(667)
Representative proteomes NCBI
(457)
Meta
(17)
RP15
(39)
RP35
(99)
RP55
(117)
RP75
(132)
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External links

MyHits provides a collection of tools to handle multiple sequence alignments. For example, one can refine a seed alignment (sequence addition or removal, re-alignment or manual edition) and then search databases for remote homologs using HMMER3.

Pfam alignments:

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Trees

This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.

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Curation and family details

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Seed source: pdb_1wj9
Previous IDs: none
Type: Domain
Author: Mistry J
Number in seed: 50
Number in full: 667
Average length of the domain: 206.90 aa
Average identity of full alignment: 36 %
Average coverage of the sequence by the domain: 97.62 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 25.0 25.0
Trusted cut-off 27.4 25.9
Noise cut-off 21.0 20.6
Model length: 214
Family (HMM) version: 6
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Species distribution

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Structures

For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the CRISPR_assoc domain has been found. There are 14 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.

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