ID   XYLB_BUTFI              Reviewed;         517 AA.
AC   P45982;
DT   01-NOV-1995, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1995, sequence version 1.
DT   02-SEP-2026, entry version 82.
DE   RecName: Full=Xylosidase/arabinosidase;
DE   Includes:
DE     RecName: Full=Beta-xylosidase;
DE              EC=3.2.1.37;
DE     AltName: Full=1,4-beta-D-xylan xylohydrolase;
DE     AltName: Full=Xylan 1,4-beta-xylosidase;
DE   Includes:
DE     RecName: Full=Alpha-L-arabinofuranosidase;
DE              Short=Arabinosidase;
DE              EC=3.2.1.55;
GN   Name=xylB;
OS   Butyrivibrio fibrisolvens.
OC   Bacteria; Bacillati; Bacillota; Clostridia; Lachnospirales;
OC   Lachnospiraceae; Butyrivibrio.
OX   NCBI_TaxID=831;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=1905520; DOI=10.1128/aem.57.4.1227-1234.1991;
RA   Utt E.A., Eddy C.K., Keshav K.F., Ingram L.O.;
RT   "Sequencing and expression of the Butyrivibrio fibrisolvens xylB gene
RT   encoding a novel bifunctional protein with beta-D-xylosidase and alpha-L-
RT   arabinofuranosidase activities.";
RL   Appl. Environ. Microbiol. 57:1227-1234(1991).
CC   -!- FUNCTION: Has a 1.6-fold higher activity as an arabinosidase than as a
CC       beta-xylosidase when tested on the substrates nitrophenyl-beta-D-
CC       xylopyranoside and P-nitrophenyl-alpha-L-arabinofuranoside.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=Hydrolysis of (1->4)-beta-D-xylans, to remove successive D-
CC         xylose residues from the non-reducing termini.; EC=3.2.1.37;
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=Hydrolysis of terminal non-reducing alpha-L-arabinofuranoside
CC         residues in alpha-L-arabinosides.; EC=3.2.1.55;
CC   -!- SIMILARITY: Belongs to the glycosyl hydrolase 43 family. {ECO:0000305}.
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DR   EMBL; M55537; AAA63610.1; -; Genomic_DNA.
DR   PIR; A49776; A49776.
DR   AlphaFoldDB; P45982; -.
DR   SMR; P45982; -.
DR   CAZy; CBM91; Carbohydrate-Binding Module Family 91.
DR   CAZy; GH43; Glycoside Hydrolase Family 43.
DR   GO; GO:0046556; F:alpha-L-arabinofuranosidase activity; IEA:UniProtKB-EC.
DR   GO; GO:0009044; F:xylan 1,4-beta-xylosidase activity; IEA:UniProtKB-EC.
DR   GO; GO:0005975; P:carbohydrate metabolic process; IEA:InterPro.
DR   CDD; cd18617; GH43_XynB-like; 1.
DR   Gene3D; 2.60.120.200; -; 1.
DR   Gene3D; 2.115.10.20; Glycosyl hydrolase domain, family 43; 1.
DR   InterPro; IPR013320; ConA-like_dom_sf.
DR   InterPro; IPR041542; GH43_C2.
DR   InterPro; IPR006710; Glyco_hydro_43.
DR   InterPro; IPR023296; Glyco_hydro_beta-prop_sf.
DR   InterPro; IPR051795; Glycosyl_Hydrlase_43.
DR   PANTHER; PTHR42812; BETA-XYLOSIDASE; 1.
DR   PANTHER; PTHR42812:SF12; BETA-XYLOSIDASE-RELATED; 1.
DR   Pfam; PF17851; GH43_C2; 1.
DR   Pfam; PF04616; Glyco_hydro_43; 1.
DR   SUPFAM; SSF75005; Arabinanase/levansucrase/invertase; 1.
DR   SUPFAM; SSF49899; Concanavalin A-like lectins/glucanases; 1.
PE   3: Inferred from homology;
KW   Carbohydrate metabolism; Glycosidase; Hydrolase; Multifunctional enzyme;
KW   Polysaccharide degradation; Xylan degradation.
FT   CHAIN           1..517
FT                   /note="Xylosidase/arabinosidase"
FT                   /id="PRO_0000057694"
FT   ACT_SITE        15
FT                   /note="Proton acceptor"
FT                   /evidence="ECO:0000250|UniProtKB:A7LXU0"
FT   ACT_SITE        185
FT                   /note="Proton donor"
FT                   /evidence="ECO:0000250|UniProtKB:A7LXU0"
FT   SITE            123
FT                   /note="Important for catalytic activity, responsible for
FT                   pKa modulation of the active site Glu and correct
FT                   orientation of both the proton donor and substrate"
FT                   /evidence="ECO:0000250|UniProtKB:A7LXU0"
SQ   SEQUENCE   517 AA;  58222 MW;  F1B645F76F6FE0B5 CRC64;
     MVIANNPILK GFYPDPSICR KGDDFYLVCS SFVYAPGVPI FHTKDLAHFE QIGNILDRES
     QLPLSGDISR GIFAPTIREH NGIFYMITTN VSSGGNFIVT AKDPAGPWSE PYYLGEDEAP
     GIDPSLFFDD DGKCYYVGTR PNPDGVRYNG DWEIWVQELD LEQMKLVGPS MAIWKGALKD
     VIWPEGPHLY KKDGYYYLLH AEAGTSFEHA ISVARSKELF KWFEGCPRNP IFTHRNLGKD
     YPVCNVGHAD LVDDINGNWY MVMLASRPCK GKCSLGRETF LAKVIWEDGW PVVNPGVGRL
     TDEVEMDLPE YRFSKEITTK DKMTFEETVL DDRFVGIERR SEDFYSLTDN PGFLRLKLRP
     EAIENTGNPS YLGIRQKTHS FRASCGLKFT PAKDNECAGM VLFQNNENHL ELLVVKKKDK
     LQFKVGPVIK GTKIRLATFD ISSGDLEIIL EAANQLANIY IKKNNEKILV AECIDLSPYT
     TEESGGFVGC TIGLYASSNG KTSDNYCDYS YFTVEEV
//