P32138 · SQASE_ECOLI

Function

function

Catalyzes the hydrolysis of sulfoquinovosyl diacylglycerides (SQDG) to sulfoquinovose (SQ), which is then degraded by E.coli through the SQ Embden-Meyerhof-Parnas (SQ-EMP) sulfoglycolysis pathway as a source of carbon and sulfur. Therefore, is likely involved in the utilization of the sulfoquinovose headgroup found in ubiquitous plant sulfolipids (PubMed:26878550).
Is also able to hydrolyze simple sulfoquinovosides such as sulfoquinovosyl glycerol (SQGro) (PubMed:26878550, PubMed:30276262).
In vitro, can use the substrate analog para-nitrophenyl alpha-sulfoquinovoside (PNPSQ), but shows no detectable activity toward 4-nitrophenyl alpha-D-glucopyranoside (PNPGlc) (PubMed:26878550, PubMed:30276262).
Is a retaining glycoside hydrolase, since it forms the alpha anomer of SQ (PubMed:26878550).
Also exhibits some alpha-glucosidase activity against alpha-glucosyl fluoride in vitro, although natural substrates, such as alpha-glucobioses are scarcely hydrolyzed (PubMed:15294295).

Catalytic activity

Activity regulation

Is inactivated in vitro by the mechanism-based inactivator 5-fluoro-beta-L-idopyranosyl fluoride (5FIdoF) that yields a covalent glycosyl-enzyme complex with the active site nucleophile Asp-405.

Kinetics

KM SUBSTRATE pH TEMPERATURE[C] NOTES EVIDENCE
0.22 mMpara-nitrophenyl alpha-sulfoquinovoside
kcat is 14.3 sec-1 with para-nitrophenyl alpha-sulfoquinovoside as substrate.

pH Dependence

Optimum pH is 6.

Pathway

Glycolipid metabolism.

Features

Showing features for binding site, active site.

TypeIDPosition(s)Description
Binding site288a 6-sulfo-alpha-D-quinovosyldiacylglycerol (UniProtKB | ChEBI)
Binding site301a 6-sulfo-alpha-D-quinovosyldiacylglycerol (UniProtKB | ChEBI)
Binding site302a 6-sulfo-alpha-D-quinovosyldiacylglycerol (UniProtKB | ChEBI)
Binding site304a 6-sulfo-alpha-D-quinovosyldiacylglycerol (UniProtKB | ChEBI)
Active site405Nucleophile
Active site408
Active site472Proton donor
Binding site537a 6-sulfo-alpha-D-quinovosyldiacylglycerol (UniProtKB | ChEBI)

GO annotations

AspectTerm
Molecular Functioncarbohydrate binding
Molecular Functionhydrolase activity, hydrolyzing O-glycosyl compounds
Molecular Functionsulfoquinovosidase activity
Biological Process6-sulfoquinovose(1-) catabolic process to glycerone phosphate and 3-sulfolactaldehyde
Biological Processcarbohydrate metabolic process

Keywords

Enzyme and pathway databases

Protein family/group databases

Names & Taxonomy

Protein names

  • Recommended name
    Sulfoquinovosidase
  • EC number
  • Short names
    SQase

Gene names

    • Name
      yihQ
    • Synonyms
      squQ
    • Ordered locus names
      b3878, JW3849

Organism names

  • Taxonomic identifier
  • Strains
    • K12 / MG1655 / ATCC 47076
    • K12 / W3110 / ATCC 27325 / DSM 5911
  • Taxonomic lineage
    Bacteria > Pseudomonadota > Gammaproteobacteria > Enterobacterales > Enterobacteriaceae > Escherichia

Accessions

  • Primary accession
    P32138
  • Secondary accessions
    • P76775
    • Q2M8H5

Proteomes

Phenotypes & Variants

Features

Showing features for mutagenesis.

TypeIDPosition(s)Description
Mutagenesis2622000-fold decrease in catalytic efficiency with PNPSQ as substrate. 100-fold decrease in catalytic efficiency with PNPSQ as substrate; when associated with E-288.
Mutagenesis288500-fold decrease in catalytic efficiency with PNPSQ as substrate. 100-fold decrease in catalytic efficiency with PNPSQ as substrate; when associated with K-262. Loses activity against PNPSQ, but in contrast to wild-type, possesses a very weak alpha-glucosidase activity against para-nitrophenyl alpha-D-glucopyranoside.
Mutagenesis301Loss of catalytic activity.
Mutagenesis301Almost complete loss of catalytic activity.
Mutagenesis30113-fold decrease in substrate affinity and 4600-fold decrease in catalytic activity.
Mutagenesis304Loss of catalytic activity.
Mutagenesis405Loss of catalytic activity.
Mutagenesis472Loss of catalytic activity.

PTM/Processing

Features

Showing features for chain.

TypeIDPosition(s)Description
ChainPRO_00001853721-678Sulfoquinovosidase

Proteomic databases

Expression

Induction

Induced during growth with sulfoquinovose.

Interaction

Protein-protein interaction databases

Family & Domains

Domain

Structural analysis revealed the molecular coevolution of catalytically important amino acid pairs directly involved in substrate recognition, as well as structurally important pairs distal to the active site.

Sequence similarities

Belongs to the glycosyl hydrolase 31 family.

Phylogenomic databases

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Length
    678
  • Mass (Da)
    77,275
  • Last updated
    1998-07-15 v3
  • Checksum
    85869F52BB72FEE7
MDTPRPQLLDFQFHQNNDSFTLHFQQRLILTHSKDNPCLWIGSGIADIDMFRGNFSIKDKLQEKIALTDAIVSQSPDGWLIHFSRGSDISATLNISADDQGRLLLELQNDNLNHNRIWLRLAAQPEDHIYGCGEQFSYFDLRGKPFPLWTSEQGVGRNKQTYVTWQADCKENAGGDYYWTFFPQPTFVSTQKYYCHVDNSCYMNFDFSAPEYHELALWEDKATLRFECADTYISLLEKLTALLGRQPELPDWIYDGVTLGIQGGTEVCQKKLDTMRNAGVKVNGIWAQDWSGIRMTSFGKRVMWNWKWNSENYPQLDSRIKQWNQEGVQFLAYINPYVASDKDLCEEAAQHGYLAKDASGGDYLVEFGEFYGGVVDLTNPEAYAWFKEVIKKNMIELGCGGWMADFGEYLPTDTYLHNGVSAEIMHNAWPALWAKCNYEALEETGKLGEILFFMRAGSTGSQKYSTMMWAGDQNVDWSLDDGLASVVPAALSLAMTGHGLHHSDIGGYTTLFEMKRSKELLLRWCDFSAFTPMMRTHEGNRPGDNWQFDGDAETIAHFARMTTVFTTLKPYLKEAVALNAKSGLPVMRPLFLHYEDDAHTYTLKYQYLLGRDILVAPVHEEGRSDWTLYLPEDNWVHAWTGEAFRGGEVTVNAPIGKPPVFYRADSEWAALFASLKSI

Features

Showing features for sequence conflict.

TypeIDPosition(s)Description
Sequence conflict358in Ref. 1; AAB03011
Sequence conflict517in Ref. 1; AAB03011

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
L19201
EMBL· GenBank· DDBJ
AAB03011.1
EMBL· GenBank· DDBJ
Genomic DNA
U00096
EMBL· GenBank· DDBJ
AAC76875.1
EMBL· GenBank· DDBJ
Genomic DNA
AP009048
EMBL· GenBank· DDBJ
BAE77431.1
EMBL· GenBank· DDBJ
Genomic DNA

Genome annotation databases

Similar Proteins

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