CSM6B_STRTR
ID CSM6B_STRTR Reviewed; 386 AA.
AC A0A0A7HFE6;
DT 16-JAN-2019, integrated into UniProtKB/Swiss-Prot.
DT 04-MAR-2015, sequence version 1.
DT 25-MAY-2022, entry version 10.
DE RecName: Full=CRISPR system endoribonuclease Csm6' {ECO:0000303|PubMed:25458845};
DE EC=3.1.-.- {ECO:0000269|PubMed:28663439};
DE AltName: Full=CRISPR type III-A associated protein Csm6-2 {ECO:0000305};
GN Name=csm6' {ECO:0000303|PubMed:25458845};
OS Streptococcus thermophilus.
OC Bacteria; Firmicutes; Bacilli; Lactobacillales; Streptococcaceae;
OC Streptococcus.
OX NCBI_TaxID=1308;
RN [1]
RP NUCLEOTIDE SEQUENCE [GENOMIC DNA], FUNCTION IN PHAGE RESISTANCE, AND
RP TARGETS SSRNA.
RC STRAIN=DGCC8004;
RX PubMed=25458845; DOI=10.1016/j.molcel.2014.09.027;
RA Tamulaitis G., Kazlauskiene M., Manakova E., Venclovas C., Nwokeoji A.O.,
RA Dickman M.J., Horvath P., Siksnys V.;
RT "Programmable RNA shredding by the type III-A CRISPR-Cas system of
RT Streptococcus thermophilus.";
RL Mol. Cell 56:506-517(2014).
RN [2]
RP FUNCTION.
RC STRAIN=DGCC8004;
RX PubMed=27105119; DOI=10.1016/j.molcel.2016.03.024;
RA Kazlauskiene M., Tamulaitis G., Kostiuk G., Venclovas C., Siksnys V.;
RT "Spatiotemporal control of type III-A CRISPR-Cas immunity: coupling DNA
RT degradation with the target RNA recognition.";
RL Mol. Cell 62:295-306(2016).
RN [3]
RP FUNCTION, ACTIVITY REGULATION, SUBUNIT, AND MUTAGENESIS OF
RP 331-ARG--HIS-336.
RC STRAIN=DGCC8004;
RX PubMed=28663439; DOI=10.1126/science.aao0100;
RA Kazlauskiene M., Kostiuk G., Venclovas C., Tamulaitis G., Siksnys V.;
RT "A cyclic oligonucleotide signaling pathway in type III CRISPR-Cas
RT systems.";
RL Science 357:605-609(2017).
CC -!- FUNCTION: CRISPR (clustered regularly interspaced short palindromic
CC repeat) is an adaptive immune system that provides protection against
CC mobile genetic elements (viruses, transposable elements and conjugative
CC plasmids). CRISPR clusters contain spacers, sequences complementary to
CC antecedent mobile elements, and target invading nucleic acids. CRISPR
CC clusters are transcribed and processed into CRISPR RNA (crRNA). The
CC type III-A Csm complex binds crRNA and acts as a crRNA-guided RNase,
CC DNase and cyclic oligoadenylate synthase; binding of target RNA cognate
CC to the crRNA is required for all activities. In a heterologous host
CC this Csm effector complex restricts ssRNA phage MS2, suggesting it may
CC target RNA viruses in vivo. This protein is not part of the Csm
CC complex. {ECO:0000269|PubMed:25458845}.
CC -!- FUNCTION: Csm functions as a non-specific ssDNase. Base-pairing between
CC crRNA and target RNA to form a ternary Csm complex activates a ssDNase
CC activity; target RNA cleavage suppresses the ssDNase, a temporal
CC control that prevents uncontrolled DNA degradation. Viral RNA
CC transcripts probably tether the Csm complex to the viral genome,
CC recruiting Cas10 ssDNA activity which is able to degrade DNA in the
CC transcription bubble, spatially controlling the DNase activity.
CC {ECO:0000269|PubMed:27105119}.
CC -!- FUNCTION: A single-strand-specific endoribonuclease (ssRNase) that is
CC approximately 1000-fold stimulated by cyclic oligoadenylate (cOA);
CC although several species of cOA are synthesized by this organism only
CC cyclic hexaadenylate (cA6) stimulates the ssRNase activity. Cleaves
CC preferentially within GA or AA dinucleotides, although the presence of
CC cA6 broadens the preference. {ECO:0000269|PubMed:28663439}.
CC -!- ACTIVITY REGULATION: Non-specific ssRNase activity is stimulated about
CC 1000-fold by cyclic oligoadenylate (cOA), a second messenger produced
CC by Cas10 of the ternary Csm effector complex in the presence of a
CC cognate target RNA. {ECO:0000269|PubMed:28663439}.
CC -!- SUBUNIT: Homodimer (PubMed:28663439). The composite ssRNase active site
CC is formed at the dimer interface (By similarity).
CC {ECO:0000250|UniProtKB:Q53W17, ECO:0000269|PubMed:28663439}.
CC -!- DOMAIN: The N-terminal CRISPR-associated Rossman fold (CARF) probably
CC binds the cA6 effector. ssRNase activity resides in the C-terminal HEPN
CC domain. {ECO:0000250|UniProtKB:Q53W17}.
CC -!- MISCELLANEOUS: Encoded in a type III-A CRISPR locus.
CC {ECO:0000269|PubMed:25458845}.
CC -!- SIMILARITY: Belongs to the CRISPR-associated Csm6 family.
CC {ECO:0000305}.
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DR EMBL; KM222358; AIZ03609.1; -; Genomic_DNA.
DR AlphaFoldDB; A0A0A7HFE6; -.
DR SMR; A0A0A7HFE6; -.
DR GO; GO:0004519; F:endonuclease activity; IEA:UniProtKB-KW.
DR GO; GO:0000166; F:nucleotide binding; IEA:UniProtKB-KW.
DR GO; GO:0003723; F:RNA binding; IEA:UniProtKB-KW.
DR GO; GO:0051607; P:defense response to virus; IEA:UniProtKB-KW.
DR InterPro; IPR013489; CRISPR-assoc_prot_Csm6.
DR Pfam; PF09659; Cas_Csm6; 1.
DR TIGRFAMs; TIGR02672; cas_csm6; 1.
PE 1: Evidence at protein level;
KW Antiviral defense; Endonuclease; Hydrolase; Nuclease; Nucleotide-binding;
KW RNA-binding.
FT CHAIN 1..386
FT /note="CRISPR system endoribonuclease Csm6'"
FT /id="PRO_0000446127"
FT REGION 1..146
FT /note="CARF domain"
FT /evidence="ECO:0000303|PubMed:28663439"
FT REGION 147..386
FT /note="HEPN domain"
FT /evidence="ECO:0000303|PubMed:28663439"
FT MUTAGEN 331..336
FT /note="RNKVAH->ANKVAA: No ssRNase activity even in presence
FT of cOA."
FT /evidence="ECO:0000269|PubMed:28663439"
SQ SEQUENCE 386 AA; 44852 MW; 241F22EA017E5C61 CRC64;
MRVLISAVGD TDPFRNFHDG SLIHIARKYR PEKVILIFSE HTAKKQGNIE KALFSIAPNY
EPELIIHDPI ISDNEVHIFD VMFQRFSDIL QEYYTKEDEF ILNLSSATPQ IKSALFVINR
LNGINVKAVQ VSSPEHASNE NIGHDNDENI DELIEVNKDN KVNFIDRTIE DNAEKFSQAL
LKKTARDFIE KFDYKAALDI LDQLSDFPNL KSVREEIRDV VNCLSKQDVP KGLRHKKLKE
EEQKILSAYL TIELQRERGN VSESFIRIKN LTEFILEDYI EKRYPGLIDE YCEDIQKYYL
SLFDYSKLLK ATKEFKLKRT IAPIIDMNSS RNKVAHSLSP LDSDAVKQLG IAMKTLKTLV
REQYHFSQSD FNFYHDLNKI LLTKLN
