ID   CIRA_CHAPA              Reviewed;          30 AA.
AC   P56871; P82250;
DT   30-MAY-2000, integrated into UniProtKB/Swiss-Prot.
DT   05-DEC-2001, sequence version 2.
DT   25-MAY-2022, entry version 76.
DE   RecName: Full=Circulin-A;
DE            Short=CIRA;
OS   Chassalia parviflora.
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   asterids; lamiids; Gentianales; Rubiaceae; Rubioideae; Palicoureeae;
OC   Chassalia.
OX   NCBI_TaxID=58431;
RN   [1]
RP   PROTEIN SEQUENCE.
RX   PubMed=4288271; DOI=10.1007/bf02144681;
RA   Fujikawa K., Suketa Y., Hayashi K., Suzuki T.;
RT   "Chemical structure of circulin A.";
RL   Experientia 21:307-308(1965).
RN   [2]
RP   PROTEIN SEQUENCE, AND MASS SPECTROMETRY.
RX   DOI=10.1021/ja00099a064;
RA   Gustafson K.R., Sowder R.C. II, Henderson L.E., Parson I.C., Kashman Y.,
RA   Cardellina J.H. Jr., McMahon J.B., Buckheit R.W. Jr., Pannell L.K.,
RA   Boyd M.R.;
RT   "Circulins A and B: novel HIV-inhibitor macrocyclic peptide from tropical
RT   tree Chassalia parvifolia.";
RL   J. Am. Chem. Soc. 116:9337-9338(1994).
RN   [3]
RP   DISULFIDE BONDS.
RX   PubMed=8920961; DOI=10.1006/bbrc.1996.1708;
RA   Derua R., Gustafson K.R., Pannell L.K.;
RT   "Analysis of the disulfide linkage pattern in circulin A and B, HIV-
RT   inhibitory macrocyclic peptides.";
RL   Biochem. Biophys. Res. Commun. 228:632-638(1996).
RN   [4]
RP   SYNTHESIS, AND ANTIBACTERIAL ACTIVITY.
RX   PubMed=10430870; DOI=10.1073/pnas.96.16.8913;
RA   Tam J.P., Lu Y.-A., Yang J.-L., Chiu K.-W.;
RT   "An unusual structural motif of antimicrobial peptides containing end-to-
RT   end macrocycle and cystine-knot disulfides.";
RL   Proc. Natl. Acad. Sci. U.S.A. 96:8913-8918(1999).
RN   [5]
RP   STRUCTURE BY NMR.
RX   PubMed=9878410; DOI=10.1006/jmbi.1998.2276;
RA   Daly N.L., Koltay A., Gustafson K.R., Boyd M.R., Casas-Finet J.R.,
RA   Craik D.J.;
RT   "Solution structure by NMR of circulin A: a macrocyclic knotted peptide
RT   having anti-HIV activity.";
RL   J. Mol. Biol. 285:333-345(1999).
CC   -!- FUNCTION: Probably participates in a plant defense mechanism. Has
CC       antibiotic activity. Inhibits the cytopathic effects and replication of
CC       the human immunodeficiency virus. Active against the Gram-positive
CC       S.aureus with a minimum inhibition concentration of approximately 0.2
CC       microM. Relatively ineffective against Gram-negative bacteria such as
CC       E.coli and P.aeruginosa.
CC   -!- DOMAIN: The presence of a 'disulfide through disulfide knot'
CC       structurally defines this protein as a knottin.
CC   -!- PTM: This is a cyclic peptide.
CC   -!- MASS SPECTROMETRY: Mass=3153.3; Method=FAB;
CC       Evidence={ECO:0000269|Ref.2};
CC   -!- SIMILARITY: Belongs to the cyclotide family. Bracelet subfamily.
CC       {ECO:0000255|PROSITE-ProRule:PRU00395}.
CC   -!- CAUTION: This peptide is cyclic. The start position was chosen by
CC       similarity to OAK1 (kalata-B1) for which the DNA sequence is known.
CC       {ECO:0000305}.
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DR   PDB; 1BH4; NMR; -; A=4-30.
DR   PDBsum; 1BH4; -.
DR   AlphaFoldDB; P56871; -.
DR   SMR; P56871; -.
DR   EvolutionaryTrace; P56871; -.
DR   GO; GO:0042742; P:defense response to bacterium; IEA:UniProtKB-KW.
DR   InterPro; IPR005535; Cyclotide.
DR   InterPro; IPR012323; Cyclotide_bracelet_CS.
DR   InterPro; IPR036146; Cyclotide_sf.
DR   Pfam; PF03784; Cyclotide; 1.
DR   PIRSF; PIRSF037891; Cycloviolacin; 1.
DR   SUPFAM; SSF57038; SSF57038; 1.
DR   PROSITE; PS51052; CYCLOTIDE; 1.
DR   PROSITE; PS60008; CYCLOTIDE_BRACELET; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Antibiotic; Antimicrobial; Direct protein sequencing;
KW   Disulfide bond; Knottin; Plant defense.
FT   PEPTIDE         1..30
FT                   /note="Circulin-A"
FT                   /id="PRO_0000043599"
FT   DISULFID        4..20
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00395,
FT                   ECO:0000269|PubMed:8920961"
FT   DISULFID        8..22
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00395,
FT                   ECO:0000269|PubMed:8920961"
FT   DISULFID        13..27
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00395,
FT                   ECO:0000269|PubMed:8920961"
FT   CROSSLNK        1..30
FT                   /note="Cyclopeptide (Gly-Asn)"
FT   STRAND          9..11
FT                   /evidence="ECO:0007829|PDB:1BH4"
FT   HELIX           15..18
FT                   /evidence="ECO:0007829|PDB:1BH4"
FT   STRAND          28..30
FT                   /evidence="ECO:0007829|PDB:1BH4"
SQ   SEQUENCE   30 AA;  3176 MW;  19D19A52EE9C58CF CRC64;
     GIPCGESCVW IPCISAALGC SCKNKVCYRN