P76632 (CSE2_ECOLI) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names

Recommended name:
CRISPR system Cascade subunit CasB

Gene names

Name:	casB
Synonyms:	cse2, ygcK
Ordered Locus Names:	b2759, JW2729

Organism

Escherichia coli (strain K12) [Reference proteome] [HAMAP]

Taxonomic identifier

83333 [NCBI]

Taxonomic lineage

cellular organisms › Bacteria › Proteobacteria › Gammaproteobacteria › Enterobacteriales › Enterobacteriaceae › Escherichia › Escherichia coli

Protein attributes

Sequence length	160 AA.
Sequence status	Complete.
Protein existence	Evidence at protein level

General annotation (Comments)

Function	CRISPR (clustered regularly interspaced short palindromic repeat), is an adaptive immune system that provides protection against mobile genetic elements (viruses, transposable elements and conjugative plasmids). CRISPR clusters contain sequences complementary to antecedent mobile elements and target invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA). Ref.6 Ref.7 A component of Cascade, which participates in CRISPR interference, the third stage of CRISPR immunity. Cascade binds both crRNA and in a sequence-specific manner negatively supercoiled dsDNA target. This leads to the formation of an R-loop in which the crRNA binds the target DNA, displacing the noncomplementary strand. Cas3 is recruited to Cascade, nicks target DNA and then unwinds and cleaves the target, leading to DNA degradation and invader neutralization. Ref.6 Ref.7
Subunit structure	Homodimer. Part of the Cascade ribonucleoprotein complex, with stoichiometry CasA1,CasB2, CasC6,CasD1,CasE(1)-crRNA1. The CasB homodimer forms a cleft that cradles the 3' end of the crRNA. Interacts directly with crRNA, CasA, CasC and CasE. Stable subcomplexes of CasBCDE-crRNA and CasCDE-crRNA also form, both of which are able to bind target dsDNA. Binding of target ssRNA or dsDNA causes a conformational change in the Cascade complex. Ref.3 Ref.6 Ref.7 Ref.8 Ref.9
Induction	Repressed by H-NS, activated by LeuO. Activated by the BaeSR two-component regulatory system, possibly due to envelope stress. Part of the casABCDE-ygbT-ygbF operon. Ref.4 Ref.5 Ref.6
Disruption phenotype	Loss of resistance to bacteriophage lambda infection, loss of plasmid silencing. Increased levels of 57 nucleotide crRNA and also 2 and 3 spacer-repeat units. Ref.3 Ref.6 Ref.7
Sequence similarities	Belongs to the CRISPR-associated CasB/Cse2 family.
Mass spectrometry	Molecular mass is 21261.5±1.1 Da from positions 1 - 160. Ref.7
Sequence caution	The sequence AAA69269.1 differs from that shown. Reason: Frameshift at position 130.

Ontologies

Keywords
Biological process	Antiviral defense
Ligand	RNA-binding
Technical term	Complete proteome Reference proteome
Gene Ontology (GO)
Biological_process	defense response to virus Inferred from mutant phenotype Ref.3. Source: EcoCyc
Cellular_component	protein complex Inferred from direct assay Ref.3. Source: EcoCyc
Molecular_function	RNA binding Inferred from electronic annotation. Source: UniProtKB-KW
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Chain	1 – 160	160	CRISPR system Cascade subunit CasB		PRO_0000169323

Sequences

	Sequence		Length	Mass (Da)
	P76632 [UniParc]. Last modified February 1, 1997. Version 1. Checksum: F2493AAD46595E5C	FASTA	160	18,702
	10 20 30 40 50 60 MADEIDAMAL YRAWQQLDNG SCAQIRRVSE PDELRDIPAF YRLVQPFGWE NPRHQQALLR 70 80 90 100 110 120 MVFCLSAGKN VIRHQDKKSE QTTGISLGRA LANSGRINER RIFQLIRADR TADMVQLRRL 130 140 150 160 LTHAEPVLDW PLMARMLTWW GKRERQQLLE DFVLTTNKNA

References

	« Hide 'large scale' referencesShow 'large scale' references »
[1]	"The complete genome sequence of Escherichia coli K-12." Blattner F.R., Plunkett G. III, Bloch C.A., Perna N.T., Burland V., Riley M., Collado-Vides J., Glasner J.D., Rode C.K., Mayhew G.F., Gregor J., Davis N.W., Kirkpatrick H.A., Goeden M.A., Rose D.J., Mau B., Shao Y. Science 277:1453-1474(1997) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: K12 / MG1655 / ATCC 47076.
[2]	"Highly accurate genome sequences of Escherichia coli K-12 strains MG1655 and W3110." Hayashi K., Morooka N., Yamamoto Y., Fujita K., Isono K., Choi S., Ohtsubo E., Baba T., Wanner B.L., Mori H., Horiuchi T. Mol. Syst. Biol. 2:E1-E5(2006) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: K12 / W3110 / ATCC 27325 / DSM 5911.
[3]	"Small CRISPR RNAs guide antiviral defense in prokaryotes." Brouns S.J., Jore M.M., Lundgren M., Westra E.R., Slijkhuis R.J., Snijders A.P., Dickman M.J., Makarova K.S., Koonin E.V., van der Oost J. Science 321:960-964(2008) [PubMed] [Europe PMC] [Abstract] Cited for: SUBUNIT, DISRUPTION PHENOTYPE. Strain: K12 / W3110 / ATCC 27325 / DSM 5911.
[4]	"Involvement of the leucine response transcription factor LeuO in regulation of the genes for sulfa drug efflux." Shimada T., Yamamoto K., Ishihama A. J. Bacteriol. 191:4562-4571(2009) [PubMed] [Europe PMC] [Abstract] Cited for: OPERON STRUCTURE, INDUCTION BY LEUO. Strain: K12 / BW25113.
[5]	"Identification and characterization of E. coli CRISPR-cas promoters and their silencing by H-NS." Pul U., Wurm R., Arslan Z., Geissen R., Hofmann N., Wagner R. Mol. Microbiol. 75:1495-1512(2010) [PubMed] [Europe PMC] [Abstract] Cited for: INDUCTION BY H-NS. Strain: K12.
[6]	"Envelope stress is a trigger of CRISPR RNA-mediated DNA silencing in Escherichia coli." Perez-Rodriguez R., Haitjema C., Huang Q., Nam K.H., Bernardis S., Ke A., DeLisa M.P. Mol. Microbiol. 79:584-599(2011) [PubMed] [Europe PMC] [Abstract] Cited for: SUBUNIT, INDUCTION BY BAER, ROLE IN PLASMID SILENCING, DISRUPTION PHENOTYPE. Strain: K12 / BW25113.
[7]	"Structural basis for CRISPR RNA-guided DNA recognition by Cascade." Jore M.M., Lundgren M., van Duijn E., Bultema J.B., Westra E.R., Waghmare S.P., Wiedenheft B., Pul U., Wurm R., Wagner R., Beijer M.R., Barendregt A., Zhou K., Snijders A.P., Dickman M.J., Doudna J.A., Boekema E.J., Heck A.J., van der Oost J., Brouns S.J. Nat. Struct. Mol. Biol. 18:529-536(2011) [PubMed] [Europe PMC] [Abstract] Cited for: FUNCTION IN CASCADE, MASS SPECTROMETRY, SUBUNIT, STRUCTURE BY ELECTRON MICROSCOPY, INTERACTION WITH CASC, DISRUPTION PHENOTYPE. Strain: K12.
[8]	"Structures of the RNA-guided surveillance complex from a bacterial immune system." Wiedenheft B., Lander G.C., Zhou K., Jore M.M., Brouns S.J., van der Oost J., Doudna J.A., Nogales E. Nature 477:486-489(2011) [PubMed] [Europe PMC] [Abstract] Cited for: STRUCTURE BY ELECTRON MICROSCOPY OF CASCADE WITH AND WITHOUT TARGET RNA, RNA-BINDING, INTERACTION WITH CASA; CASC AND CASE. Strain: K12.
[9]	"CRISPR immunity relies on the consecutive binding and degradation of negatively supercoiled invader DNA by Cascade and Cas3." Westra E.R., van Erp P.B., Kunne T., Wong S.P., Staals R.H., Seegers C.L., Bollen S., Jore M.M., Semenova E., Severinov K., de Vos W.M., Dame R.T., de Vries R., Brouns S.J., van der Oost J. Mol. Cell 46:595-605(2012) [PubMed] [Europe PMC] [Abstract] Cited for: SUBUNIT, CASCADE DNA-BINDING. Strain: K12 / MG1655 / ATCC 47076.

Cross-references

Sequence databases
EMBL GenBank DDBJ	U29579 Genomic DNA. Translation: AAA69269.1. Frameshift. U00096 Genomic DNA. Translation: AAC75801.1. AP009048 Genomic DNA. Translation: BAE76836.1.
PIR	C65057.
RefSeq	NP_417239.1. NC_000913.2. YP_490968.1. NC_007779.1.
3D structure databases
ProteinModelPortal	P76632.
ModBase	Search...
Protein-protein interaction databases
DIP	DIP-12127N.
IntAct	P76632. 9 interactions.
STRING	511145.b2759.
Proteomic databases
PRIDE	P76632.
Protocols and materials databases
StructuralBiologyKnowledgebase	Search...
Genome annotation databases
EnsemblBacteria	AAC75801; AAC75801; b2759. BAE76836; BAE76836; BAE76836.
GeneID	12931745. 947223.
KEGG	ecj:Y75_p2697. eco:b2759.
PATRIC	32120928. VBIEscCol129921_2856.
Organism-specific databases
EchoBASE	EB2919.
EcoGene	EG13118. casB.
Phylogenomic databases
eggNOG	NOG40058.
HOGENOM	HOG000009769.
OMA	NGACAQI.
ProtClustDB	CLSK891789.
Enzyme and pathway databases
BioCyc	EcoCyc:G7429-MONOMER. ECOL316407:JW2729-MONOMER. MetaCyc:G7429-MONOMER.
Gene expression databases
Genevestigator	P76632.
Family and domain databases
InterPro	IPR013382. CRISPR-assoc_prot_Cse2. [Graphical view]
Pfam	PF09485. CRISPR_Cse2. 1 hit. [Graphical view]
TIGRFAMs	TIGR02548. casB_cse2. 1 hit.
ProtoNet	Search...

Entry information

Entry name

CSE2_ECOLI

Accession

Primary (citable) accession number: P76632
Secondary accession number(s): Q2MA70, Q46900

Entry history

Integrated into UniProtKB/Swiss-Prot:	November 1, 1997
Last sequence update:	February 1, 1997
Last modified:	May 1, 2013
This is version 73 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Prokaryotic Protein Annotation Program