Q09LX1 · AXE2_GEOSE

Function

function

Acetylxylan esterase involved in the degradation of xylan, a major structural heterogeneous polysaccharide found in plant biomass representing the second most abundant polysaccharide in the biosphere, after cellulose. Cleaves acetyl side groups from the xylose backbone units of the hemicellulolytic polymer xylan and xylo-oligosaccharides. Hydrolyzes about 20%-30% of the available acetyl groups on fully acetylated birch wood xylan. Completely deacetylates xylobiose peracetate (fully acetylated), and is active on both the alpha- and beta-forms of the sugar. Also hydrolyzes fully acetylated methyl-beta-D-xylopyranoside and methyl-beta-D-glucopyranoside, and the synthetic substrates 2-naphthyl acetate, 4-nitrophenyl acetate, 4-methylumbelliferyl acetate, and phenyl acetate.

Catalytic activity

  • Deacetylation of xylans and xylo-oligosaccharides.
    EC:3.1.1.72 (UniProtKB | ENZYME | Rhea)

Kinetics

KM SUBSTRATE pH TEMPERATURE[C] NOTES EVIDENCE
7 mMphenyl acetate6.030
9 mM2-naphtyl acetate6.030
3 mM4-methylumbelliferyl acetate6.030
27 mM4-nitrophenyl acetate6.030
kcat is 77 sec-1 with phenyl acetate as substrate. kcat is 190 sec-1 with 2-naphtyl acetate as substrate. kcat is 123 sec-1 with 4-methylumbelliferyl acetate as substrate. kcat is 31 sec-1 with 4-nitrophenyl acetate as substrate (at pH 6.0 and 30 degrees Celsius).

pH Dependence

Optimum pH is 7.1-9.2.

Temperature Dependence

Optimum temperature is 50-60 degrees Celsius. Is stable at 60 degrees Celsius and loses most of its activity at 70 degrees Celsius.

Pathway

Glycan degradation; xylan degradation.

Features

Showing features for active site, site.

Type
IDPosition(s)Description
Active site15Nucleophile
Site63Transition state stabilizer
Site92Transition state stabilizer
Active site191Charge relay system
Active site194Charge relay system

GO annotations

AspectTerm
Cellular Componentcytoplasm
Molecular Functionacetylxylan esterase activity
Molecular Functionlysophospholipase activity
Biological Processxylan catabolic process

Keywords

Enzyme and pathway databases

Names & Taxonomy

Protein names

  • Recommended name
    Acetylxylan esterase
  • EC number
  • Alternative names
    • Acetyl-xylooligosaccharide esterase

Gene names

    • Name
      axe2

Organism names

Accessions

  • Primary accession
    Q09LX1

Subcellular Location

Keywords

Phenotypes & Variants

Features

Showing features for mutagenesis.

TypeIDPosition(s)Description
Mutagenesis15Loss of catalytic activity.
Mutagenesis184Significant reduction in catalytic activity and modification of the quaternary structure as a homodimer; when associated with P-190.
Mutagenesis190Significant reduction in catalytic activity and modification of the quaternary structure as a homodimer; when associated with F-184.
Mutagenesis191Loss of catalytic activity.
Mutagenesis194Loss of catalytic activity.

PTM/Processing

Features

Showing features for chain.

TypeIDPosition(s)Description
ChainPRO_00004341011-219Acetylxylan esterase

Expression

Induction

Up-regulated by xylose.

Interaction

Subunit

Homooctamer, presenting a unique donut-shaped quaternary structure built of two staggered tetrameric rings. The eight active sites are organized in four closely situated pairs, which face the relatively wide internal cavity.

Family & Domains

Sequence similarities

Belongs to the 'GDSL' lipolytic enzyme family.

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Length
    219
  • Mass (Da)
    24,772
  • Last updated
    2006-10-17 v1
  • Checksum
    A3F18C97F5F69E32
MKIGSGEKLLFIGDSITDCGRARPEGEGSFGALGTGYVAYVVGLLQAVYPELGIRVVNKGISGNTVRDLKARWEEDVIAQKPDWVSIMIGINDVWRQYDLPFMKEKHVYLDEYEATLRSLVLETKPLVKGIILMTPFYIEGNEQDPMRRTMDQYGRVVKQIAEETNSLFVDTQAAFNEVLKTLYPAALAWDRVHPSVAGHMILARAFLREIGFEWVRSR

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
DQ868502
EMBL· GenBank· DDBJ
ABI49953.1
EMBL· GenBank· DDBJ
Genomic DNA

Similar Proteins

Disclaimer

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