ID   CHIA_CUCSA              Reviewed;         292 AA.
AC   P17541;
DT   01-AUG-1990, integrated into UniProtKB/Swiss-Prot.
DT   01-AUG-1990, sequence version 1.
DT   25-MAY-2022, entry version 104.
DE   RecName: Full=Acidic endochitinase;
DE            EC=3.2.1.14;
DE   Flags: Precursor;
OS   Cucumis sativus (Cucumber).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   rosids; fabids; Cucurbitales; Cucurbitaceae; Benincaseae; Cucumis.
OX   NCBI_TaxID=3659;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], AND PARTIAL PROTEIN SEQUENCE.
RC   STRAIN=cv. Wisconsin SMR-58;
RX   PubMed=2915985; DOI=10.1073/pnas.86.3.896;
RA   Metraux J.P., Burkhart W., Moyer M., Dincher S., Middlesteadt W.,
RA   Williams S., Payne G., Carnes M., Ryals J.;
RT   "Isolation of a complementary DNA encoding a chitinase with structural
RT   homology to a bifunctional lysozyme/chitinase.";
RL   Proc. Natl. Acad. Sci. U.S.A. 86:896-900(1989).
RN   [2]
RP   NUCLEOTIDE SEQUENCE.
RC   TISSUE=Leaf;
RX   PubMed=8167370; DOI=10.1094/mpmi-7-0048;
RA   Lawton K., Beck J., Potter S., Ward E., Ryals J.;
RT   "Regulation of cucumber class III chitinase gene expression.";
RL   Mol. Plant Microbe Interact. 7:48-57(1994).
CC   -!- FUNCTION: This protein functions as a defense against chitin containing
CC       fungal pathogens.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide
CC         (1->4)-beta-linkages in chitin and chitodextrins.; EC=3.2.1.14;
CC   -!- SUBCELLULAR LOCATION: Secreted, extracellular space.
CC   -!- INDUCTION: By salicylate and upon tobacco necrosis virus infection.
CC   -!- SIMILARITY: Belongs to the glycosyl hydrolase 18 family. Chitinase
CC       class II subfamily. {ECO:0000305}.
CC   ---------------------------------------------------------------------------
CC   Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms
CC   Distributed under the Creative Commons Attribution (CC BY 4.0) License
CC   ---------------------------------------------------------------------------
DR   EMBL; M24365; AAA33120.1; -; mRNA.
DR   EMBL; M84214; AAC37395.1; -; Unassigned_DNA.
DR   PIR; A31455; A31455.
DR   AlphaFoldDB; P17541; -.
DR   SMR; P17541; -.
DR   STRING; 3659.XP_004169800.1; -.
DR   CAZy; GH18; Glycoside Hydrolase Family 18.
DR   eggNOG; KOG4701; Eukaryota.
DR   GO; GO:0005615; C:extracellular space; IEA:UniProtKB-SubCell.
DR   GO; GO:0004568; F:chitinase activity; IEA:UniProtKB-EC.
DR   GO; GO:0006032; P:chitin catabolic process; IEA:UniProtKB-KW.
DR   GO; GO:0000272; P:polysaccharide catabolic process; IEA:UniProtKB-KW.
DR   CDD; cd02877; GH18_hevamine_XipI_class_III; 1.
DR   InterPro; IPR045321; Cts1-like.
DR   InterPro; IPR001223; Glyco_hydro18_cat.
DR   InterPro; IPR001579; Glyco_hydro_18_chit_AS.
DR   InterPro; IPR017853; Glycoside_hydrolase_SF.
DR   Pfam; PF00704; Glyco_hydro_18; 1.
DR   SUPFAM; SSF51445; SSF51445; 1.
DR   PROSITE; PS01095; GH18_1; 1.
DR   PROSITE; PS51910; GH18_2; 1.
PE   1: Evidence at protein level;
KW   Carbohydrate metabolism; Chitin degradation; Direct protein sequencing;
KW   Disulfide bond; Glycosidase; Hydrolase; Polysaccharide degradation;
KW   Secreted; Signal.
FT   SIGNAL          1..25
FT   CHAIN           26..292
FT                   /note="Acidic endochitinase"
FT                   /id="PRO_0000011916"
FT   DOMAIN          26..292
FT                   /note="GH18"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01258"
FT   ACT_SITE        152
FT                   /note="Proton donor"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01258"
FT   DISULFID        45..92
FT                   /evidence="ECO:0000250"
FT   DISULFID        75..82
FT                   /evidence="ECO:0000250"
FT   DISULFID        180..209
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   292 AA;  30774 MW;  2DE39D42BBDB0093 CRC64;
     MAAHKITTTL SIFFLLSSIF RSSDAAGIAI YWGQNGNEGS LASTCATGNY EFVNIAFLSS
     FGSGQAPVLN LAGHCNPDNN GCAFLSDEIN SCKSQNVKVL LSIGGGAGSY SLSSADDAKQ
     VANFIWNSYL GGQSDSRPLG AAVLDGVDFD IESGSGQFWD VLAQELKNFG QVILSAAPQC
     PIPDAHLDAA IKTGLFDSVW VQFYNNPPCM FADNADNLLS SWNQWTAFPT SKLYMGLPAA
     REAAPSGGFI PADVLISQVL PTIKASSNYG GVMLWSKAFD NGYSDSIKGS IG