ID   REOX_HALH5              Reviewed;         388 AA.
AC   Q9KB30; Q8GLI2;
DT   10-AUG-2010, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-2000, sequence version 1.
DT   02-SEP-2026, entry version 134.
DE   RecName: Full=Reducing end xylose-releasing exo-oligoxylanase {ECO:0000303|PubMed:15491996};
DE            Short=Rex {ECO:0000303|PubMed:15491996};
DE            EC=3.2.1.156;
GN   OrderedLocusNames=BH2105;
OS   Halalkalibacterium halodurans (strain ATCC BAA-125 / DSM 18197 / FERM 7344
OS   / JCM 9153 / C-125) (Bacillus halodurans).
OC   Bacteria; Bacillati; Bacillota; Bacilli; Caryophanales; Bacillaceae;
OC   Halalkalibacterium (ex Joshi et al. 2022).
OX   NCBI_TaxID=272558;
RN   [1] {ECO:0000312|EMBL:BAB05824.1}
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=ATCC BAA-125 / DSM 18197 / FERM 7344 / JCM 9153 / C-125;
RX   PubMed=11058132; DOI=10.1093/nar/28.21.4317;
RA   Takami H., Nakasone K., Takaki Y., Maeno G., Sasaki R., Masui N., Fuji F.,
RA   Hirama C., Nakamura Y., Ogasawara N., Kuhara S., Horikoshi K.;
RT   "Complete genome sequence of the alkaliphilic bacterium Bacillus halodurans
RT   and genomic sequence comparison with Bacillus subtilis.";
RL   Nucleic Acids Res. 28:4317-4331(2000).
RN   [2] {ECO:0000305}
RP   PROTEIN SEQUENCE OF 1-10, FUNCTION, CATALYTIC ACTIVITY, BIOPHYSICOCHEMICAL
RP   PROPERTIES, AND MUTAGENESIS OF GLU-70; ASP-128 AND ASP-263.
RC   STRAIN=ATCC BAA-125 / DSM 18197 / FERM 7344 / JCM 9153 / C-125;
RX   PubMed=15491996; DOI=10.1074/jbc.m409832200;
RA   Honda Y., Kitaoka M.;
RT   "A family 8 glycoside hydrolase from Bacillus halodurans C-125 (BH2105) is
RT   a reducing end xylose-releasing exo-oligoxylanase.";
RL   J. Biol. Chem. 279:55097-55103(2004).
RN   [3] {ECO:0000305, ECO:0000312|EMBL:AAN16076.1}
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 3-376.
RC   STRAIN=MIR32 {ECO:0000312|EMBL:AAN16076.1};
RA   Martinez M.A., Baigori M.D., Sineriz F.;
RT   "Partial ORF identical to Xylanase Y from B. halodurans C-125.";
RL   Submitted (JUL-2002) to the EMBL/GenBank/DDBJ databases.
RN   [4] {ECO:0000305}
RP   BIOPHYSICOCHEMICAL PROPERTIES, AND MUTAGENESIS OF ASP-263.
RX   PubMed=16301312; DOI=10.1074/jbc.m511202200;
RA   Honda Y., Kitaoka M.;
RT   "The first glycosynthase derived from an inverting glycoside hydrolase.";
RL   J. Biol. Chem. 281:1426-1431(2006).
RN   [5] {ECO:0000305}
RP   MUTAGENESIS OF TYR-198 AND ASP-263.
RX   PubMed=18263897; DOI=10.1093/glycob/cwn011;
RA   Honda Y., Fushinobu S., Hidaka M., Wakagi T., Shoun H., Taniguchi H.,
RA   Kitaoka M.;
RT   "Alternative strategy for converting an inverting glycoside hydrolase into
RT   a glycosynthase.";
RL   Glycobiology 18:325-330(2008).
RN   [6] {ECO:0000312|PDB:1WU4}
RP   X-RAY CRYSTALLOGRAPHY (1.35 ANGSTROMS).
RX   PubMed=15718242; DOI=10.1074/jbc.m413693200;
RA   Fushinobu S., Hidaka M., Honda Y., Wakagi T., Shoun H., Kitaoka M.;
RT   "Structural basis for the specificity of the reducing end xylose-releasing
RT   exo-oligoxylanase from Bacillus halodurans C-125.";
RL   J. Biol. Chem. 280:17180-17186(2005).
CC   -!- FUNCTION: Hydrolyzes xylooligosaccharides with a degree of
CC       polymerization of greater than or equal to 3, releasing xylose from the
CC       reducing end. Only hydrolyzes the beta anomers of xylooligosaccharides,
CC       with inversion of anomeric configuration. Hydrolyzes the glucose and
CC       xylose-based trisaccharides where xylose is located at the -1 subsite,
CC       GXX, XXG and GXG. Does not hydrolyze xylan, chitosan, lichenan, curdlan
CC       or carboxymethylcellulose. {ECO:0000269|PubMed:15491996}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=Hydrolysis of (1->4)-beta-D-xylose residues from the reducing
CC         end of oligosaccharides.; EC=3.2.1.156;
CC         Evidence={ECO:0000269|PubMed:15491996};
CC   -!- BIOPHYSICOCHEMICAL PROPERTIES:
CC       Kinetic parameters:
CC         KM=2.4 mM for X3 (in 50 mM sodium phosphate, pH 7.1, 40 degrees
CC         Celsius) {ECO:0000269|PubMed:15491996, ECO:0000269|PubMed:16301312};
CC         KM=5 mM for X4 (in 50 mM sodium phosphate, pH 7.1, 40 degrees
CC         Celsius) {ECO:0000269|PubMed:15491996, ECO:0000269|PubMed:16301312};
CC         KM=4.4 mM for X5 (in 50 mM sodium phosphate, pH 7.1, 40 degrees
CC         Celsius) {ECO:0000269|PubMed:15491996, ECO:0000269|PubMed:16301312};
CC         KM=18.5 mM for X6 (in 50 mM sodium phosphate, pH 7.1, 40 degrees
CC         Celsius) {ECO:0000269|PubMed:15491996, ECO:0000269|PubMed:16301312};
CC         KM=4.3 mM for X3 (in 0.1 M MOPS, pH 7.0, 30 degrees Celsius)
CC         {ECO:0000269|PubMed:15491996, ECO:0000269|PubMed:16301312};
CC       pH dependence:
CC         Optimum pH is 6.2-7.3. Stable between pH 5.0 and 9.8 for 30 minutes
CC         at 30 degrees Celsius. {ECO:0000269|PubMed:15491996,
CC         ECO:0000269|PubMed:16301312};
CC       Temperature dependence:
CC         Optimum temperature is 50 degrees Celsius. Stable up to 40 degrees
CC         Celsius. {ECO:0000269|PubMed:15491996, ECO:0000269|PubMed:16301312};
CC   -!- SIMILARITY: Belongs to the glycosyl hydrolase 8 (cellulase D) family.
CC       {ECO:0000255}.
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DR   EMBL; BA000004; BAB05824.1; -; Genomic_DNA.
DR   EMBL; AY137373; AAN16076.1; -; Genomic_DNA.
DR   PIR; A83913; A83913.
DR   RefSeq; WP_010898262.1; NC_002570.2.
DR   PDB; 1WU4; X-ray; 1.35 A; A=1-388.
DR   PDB; 1WU5; X-ray; 2.20 A; A=1-388.
DR   PDB; 1WU6; X-ray; 1.45 A; A=1-388.
DR   PDB; 2DRO; X-ray; 1.70 A; A=1-388.
DR   PDB; 2DRQ; X-ray; 2.10 A; A=1-388.
DR   PDB; 2DRR; X-ray; 1.60 A; A=1-388.
DR   PDB; 2DRS; X-ray; 2.10 A; A=1-388.
DR   PDB; 3A3V; X-ray; 1.39 A; A=1-388.
DR   AlphaFoldDB; Q9KB30; -.
DR   SMR; Q9KB30; -.
DR   STRING; 272558.gene:10728003; -.
DR   DrugBank; DB03389; alpha-D-Xylopyranose.
DR   CAZy; GH8; Glycoside Hydrolase Family 8.
DR   GeneID; 87597657; -.
DR   KEGG; bha:BH2105; -.
DR   eggNOG; COG3405; Bacteria.
DR   HOGENOM; CLU_037722_0_0_9; -.
DR   OrthoDB; 9803461at2; -.
DR   BioCyc; MetaCyc:MONOMER-17885; -.
DR   BRENDA; 3.2.1.156; 661.
DR   EvolutionaryTrace; Q9KB30; -.
DR   Proteomes; UP000001258; Chromosome.
DR   GO; GO:0033951; F:oligosaccharide reducing-end xylanase activity; EXP:UniProtKB.
DR   GO; GO:0005975; P:carbohydrate metabolic process; IEA:InterPro.
DR   Gene3D; 1.50.10.10; -; 1.
DR   InterPro; IPR008928; 6-hairpin_glycosidase_sf.
DR   InterPro; IPR012341; 6hp_glycosidase-like_sf.
DR   InterPro; IPR002037; Glyco_hydro_8.
DR   Pfam; PF01270; Glyco_hydro_8; 1.
DR   PRINTS; PR00735; GLHYDRLASE8.
DR   SUPFAM; SSF48208; Six-hairpin glycosidases; 1.
DR   PDBsum; 1WU4; -.
DR   PDBsum; 1WU5; -.
DR   PDBsum; 1WU6; -.
DR   PDBsum; 2DRO; -.
DR   PDBsum; 2DRQ; -.
DR   PDBsum; 2DRR; -.
DR   PDBsum; 2DRS; -.
DR   PDBsum; 3A3V; -.
PE   1: Evidence at protein level;
KW   3D-structure; Carbohydrate metabolism; Direct protein sequencing;
KW   Glycosidase; Hydrolase; Polysaccharide degradation; Reference proteome;
KW   Xylan degradation.
FT   CHAIN           1..388
FT                   /note="Reducing end xylose-releasing exo-oligoxylanase"
FT                   /id="PRO_0000397235"
FT   ACT_SITE        70
FT                   /note="Proton donor"
FT                   /evidence="ECO:0000250|UniProtKB:A0A0S2UQQ5"
FT   ACT_SITE        263
FT                   /note="Proton acceptor"
FT                   /evidence="ECO:0000250|UniProtKB:A0A0S2UQQ5"
FT   MUTAGEN         70
FT                   /note="E->A: Activity is 0.01% of wild type."
FT                   /evidence="ECO:0000269|PubMed:15491996"
FT   MUTAGEN         128
FT                   /note="D->A: Activity is 0.4% of wild type."
FT                   /evidence="ECO:0000269|PubMed:15491996"
FT   MUTAGEN         198
FT                   /note="Y->F: Has high levels of glycosynthase activity.
FT                   Reduced hydrolase activity."
FT                   /evidence="ECO:0000269|PubMed:18263897"
FT   MUTAGEN         263
FT                   /note="D->A: Activity is 0.02% of wild type. Has
FT                   glycosynthase activity."
FT                   /evidence="ECO:0000269|PubMed:15491996,
FT                   ECO:0000269|PubMed:16301312, ECO:0000269|PubMed:18263897"
FT   MUTAGEN         263
FT                   /note="D->C,N: Has high levels of glycosynthase activity.
FT                   Reduced hydrolase activity."
FT                   /evidence="ECO:0000269|PubMed:15491996,
FT                   ECO:0000269|PubMed:16301312, ECO:0000269|PubMed:18263897"
FT   MUTAGEN         263
FT                   /note="D->G,L,P,S,T,V: Has glycosynthase activity."
FT                   /evidence="ECO:0000269|PubMed:15491996,
FT                   ECO:0000269|PubMed:16301312, ECO:0000269|PubMed:18263897"
FT   CONFLICT        2
FT                   /note="K -> E (in Ref. 2; AA sequence)"
FT                   /evidence="ECO:0000305"
FT   HELIX           8..11
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           17..20
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           25..40
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   TURN            44..46
FT                   /evidence="ECO:0007829|PDB:3A3V"
FT   STRAND          49..52
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   TURN            53..55
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   STRAND          56..59
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   TURN            62..65
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   STRAND          66..68
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           69..81
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           85..94
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           95..99
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   STRAND          102..104
FT                   /evidence="ECO:0007829|PDB:1WU5"
FT   TURN            105..108
FT                   /evidence="ECO:0007829|PDB:3A3V"
FT   STRAND          112..114
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           127..144
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           154..167
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   STRAND          170..173
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   TURN            180..182
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   STRAND          192..194
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           196..198
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           201..210
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           213..215
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           216..233
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   TURN            236..238
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           240..242
FT                   /evidence="ECO:0007829|PDB:2DRO"
FT   STRAND          243..246
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   STRAND          249..251
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   STRAND          258..261
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           262..264
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           265..278
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           282..295
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           300..302
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   STRAND          304..306
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   STRAND          312..316
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           320..329
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           330..333
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           340..348
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           351..353
FT                   /evidence="ECO:0007829|PDB:1WU4"
FT   HELIX           358..372
FT                   /evidence="ECO:0007829|PDB:1WU4"
SQ   SEQUENCE   388 AA;  45010 MW;  C1EBA5B4A98C0E28 CRC64;
     MKKTTEGAFY TREYRNLFKE FGYSEAEIQE RVKDTWEQLF GDNPETKIYY EVGDDLGYLL
     DTGNLDVRTE GMSYGMMMAV QMDRKDIFDR IWNWTMKNMY MTEGVHAGYF AWSCQPDGTK
     NSWGPAPDGE EYFALALFFA SHRWGDGDEQ PFNYSEQARK LLHTCVHNGE GGPGHPMWNR
     DNKLIKFIPE VEFSDPSYHL PHFYELFSLW ANEEDRVFWK EAAEASREYL KIACHPETGL
     APEYAYYDGT PNDEKGYGHF FSDSYRVAAN IGLDAEWFGG SEWSAEEINK IQAFFADKEP
     EDYRRYKIDG EPFEEKSLHP VGLIATNAMG SLASVDGPYA KANVDLFWNT PVRTGNRRYY
     DNCLYLFAML ALSGNFKIWF PEGQEEEH
//