P32138 · SQASE_ECOLI
- ProteinSulfoquinovosidase
- GeneyihQ
- StatusUniProtKB reviewed (Swiss-Prot)
- Organism
- Amino acids678 (go to sequence)
- Protein existenceEvidence at protein level
- Annotation score5/5
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).
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
- a 6-sulfo-alpha-D-quinovosyldiacylglycerol + H2O = 6-sulfo-alpha-D-quinovose + a 1,2-diacyl-sn-glycerol
- 3-(6-sulfo-alpha-D-quinovosyl)glycerol + H2O = 6-sulfo-alpha-D-quinovose + glycerol
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 mM | para-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.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Binding site | 288 | a 6-sulfo-alpha-D-quinovosyldiacylglycerol (UniProtKB | ChEBI) | ||||
Sequence: Q | ||||||
Binding site | 301 | a 6-sulfo-alpha-D-quinovosyldiacylglycerol (UniProtKB | ChEBI) | ||||
Sequence: R | ||||||
Binding site | 302 | a 6-sulfo-alpha-D-quinovosyldiacylglycerol (UniProtKB | ChEBI) | ||||
Sequence: V | ||||||
Binding site | 304 | a 6-sulfo-alpha-D-quinovosyldiacylglycerol (UniProtKB | ChEBI) | ||||
Sequence: W | ||||||
Active site | 405 | Nucleophile | ||||
Sequence: D | ||||||
Active site | 408 | |||||
Sequence: E | ||||||
Active site | 472 | Proton donor | ||||
Sequence: D | ||||||
Binding site | 537 | a 6-sulfo-alpha-D-quinovosyldiacylglycerol (UniProtKB | ChEBI) | ||||
Sequence: H |
GO annotations
Aspect | Term | |
---|---|---|
Molecular Function | carbohydrate binding | |
Molecular Function | hydrolase activity, hydrolyzing O-glycosyl compounds | |
Molecular Function | sulfoquinovosidase activity | |
Biological Process | 6-sulfoquinovose(1-) catabolic process to glycerone phosphate and 3-sulfolactaldehyde | |
Biological Process | carbohydrate metabolic process |
Keywords
- Molecular function
Enzyme and pathway databases
Protein family/group databases
Names & Taxonomy
Protein names
- Recommended nameSulfoquinovosidase
- EC number
- Short namesSQase
Gene names
Organism names
- Organism
- Strains
- Taxonomic lineageBacteria > Pseudomonadota > Gammaproteobacteria > Enterobacterales > Enterobacteriaceae > Escherichia
Accessions
- Primary accessionP32138
- Secondary accessions
Proteomes
Phenotypes & Variants
Features
Showing features for mutagenesis.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Mutagenesis | 262 | 2000-fold decrease in catalytic efficiency with PNPSQ as substrate. 100-fold decrease in catalytic efficiency with PNPSQ as substrate; when associated with E-288. | ||||
Sequence: Q → K | ||||||
Mutagenesis | 288 | 500-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. | ||||
Sequence: Q → E | ||||||
Mutagenesis | 301 | Loss of catalytic activity. | ||||
Sequence: R → A or E | ||||||
Mutagenesis | 301 | Almost complete loss of catalytic activity. | ||||
Sequence: R → K | ||||||
Mutagenesis | 301 | 13-fold decrease in substrate affinity and 4600-fold decrease in catalytic activity. | ||||
Sequence: R → Q | ||||||
Mutagenesis | 304 | Loss of catalytic activity. | ||||
Sequence: W → F | ||||||
Mutagenesis | 405 | Loss of catalytic activity. | ||||
Sequence: D → A or N | ||||||
Mutagenesis | 472 | Loss of catalytic activity. | ||||
Sequence: D → A or N |
PTM/Processing
Features
Showing features for chain.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Chain | PRO_0000185372 | 1-678 | Sulfoquinovosidase | |||
Sequence: MDTPRPQLLDFQFHQNNDSFTLHFQQRLILTHSKDNPCLWIGSGIADIDMFRGNFSIKDKLQEKIALTDAIVSQSPDGWLIHFSRGSDISATLNISADDQGRLLLELQNDNLNHNRIWLRLAAQPEDHIYGCGEQFSYFDLRGKPFPLWTSEQGVGRNKQTYVTWQADCKENAGGDYYWTFFPQPTFVSTQKYYCHVDNSCYMNFDFSAPEYHELALWEDKATLRFECADTYISLLEKLTALLGRQPELPDWIYDGVTLGIQGGTEVCQKKLDTMRNAGVKVNGIWAQDWSGIRMTSFGKRVMWNWKWNSENYPQLDSRIKQWNQEGVQFLAYINPYVASDKDLCEEAAQHGYLAKDASGGDYLVEFGEFYGGVVDLTNPEAYAWFKEVIKKNMIELGCGGWMADFGEYLPTDTYLHNGVSAEIMHNAWPALWAKCNYEALEETGKLGEILFFMRAGSTGSQKYSTMMWAGDQNVDWSLDDGLASVVPAALSLAMTGHGLHHSDIGGYTTLFEMKRSKELLLRWCDFSAFTPMMRTHEGNRPGDNWQFDGDAETIAHFARMTTVFTTLKPYLKEAVALNAKSGLPVMRPLFLHYEDDAHTYTLKYQYLLGRDILVAPVHEEGRSDWTLYLPEDNWVHAWTGEAFRGGEVTVNAPIGKPPVFYRADSEWAALFASLKSI |
Proteomic databases
Expression
Induction
Induced during growth with sulfoquinovose.
Structure
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 statusComplete
- Length678
- Mass (Da)77,275
- Last updated1998-07-15 v3
- Checksum85869F52BB72FEE7
Features
Showing features for sequence conflict.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Sequence conflict | 358 | in Ref. 1; AAB03011 | ||||
Sequence: A → R | ||||||
Sequence conflict | 517 | in Ref. 1; AAB03011 | ||||
Sequence: S → T |
Keywords
- Technical term
Sequence databases
Nucleotide Sequence | Protein Sequence | Molecule Type | Status | |
---|---|---|---|---|
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 |