QuiC1 is a 635-amino acid 3-dehydroshikimate dehydratase (EC 4.2.1.118) that catalyzes the conversion of 3-dehydroshikimate to protocatechuate (3,4-dihydroxybenzoate), a key reaction in quinate and shikimate degradation pathways. This enzyme is structurally distinct from previously characterized DSDs, consisting of a fusion of two domains: an N-terminal sugar phosphate isomerase-like domain that confers DSD activity, and a C-terminal hydroxyphenyl-pyruvate dioxygenase-like domain important for optimal activity. The enzyme requires divalent metal cations (preferentially Co2+) and functions as a homodimer. QuiC1 represents a novel structural variant of dehydroshikimate dehydratases found in pseudomonads, with applications in metabolic engineering for protocatechuate production.
Definition: The activity of dehydroshikimate dehydratases containing both sugar phosphate isomerase-like and hydroxyphenyl-pyruvate dioxygenase-like domains
Justification: QuiC1 represents a structurally distinct class of DSDs with unique two-domain architecture not captured by existing GO terms
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0016829 lyase activity | IEA GO_REF:0000043 | ACCEPT | Summary: Correct and well-characterized - QuiC1 exhibits lyase activity by catalyzing dehydration reaction Reason: Accurately describes the enzyme mechanism. QuiC1 catalyzes the elimination of water from 3-dehydroshikimate to form protocatechuate, which is classified as lyase activity. |
| GO:0046279 3,4-dihydroxybenzoate biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: Correct and specific - QuiC1 directly produces protocatechuate (3,4-dihydroxybenzoate) Reason: QuiC1 catalyzes the formation of protocatechuate as its primary product, representing a key step in protocatechuate biosynthesis. |
| GO:0046565 3-dehydroshikimate dehydratase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Perfectly accurate - this is the precise enzymatic activity of QuiC1 Reason: This is the exact molecular function of QuiC1 with experimentally determined EC number 4.2.1.118. |
| GO:0046872 metal ion binding | IEA GO_REF:0000120 | ACCEPT | Summary: Correct and essential - QuiC1 requires divalent metal cations for activity Reason: QuiC1 requires divalent metal cations (Co(2+), Ni(2+), Mn(2+), Mg(2+)) for catalytic activity, with specific metal binding sites characterized. |
| GO:0000287 magnesium ion binding | IDA PMID:27706847 Structurally diverse dehydroshikimate dehydratase variants p... | ACCEPT | Summary: Experimentally confirmed - crystal structure shows specific Mg(2+) binding sites Reason: Crystal structure (PDB: 5HMQ) demonstrates specific magnesium binding sites, and biochemical assays confirm Mg(2+) can support catalytic activity. Supporting Evidence: PMID:27706847 Structurally diverse dehydroshikimate dehydratase variants participate in microbial quinate catabolism. |
| GO:0019631 quinate catabolic process | ISS PMID:27706847 Structurally diverse dehydroshikimate dehydratase variants p... | ACCEPT | Summary: Core biological process - QuiC1 is essential for quinate degradation pathway Reason: QuiC1 catalyzes a central step in quinate catabolism, converting pathway intermediate to protocatechuate for further degradation. Supporting Evidence: PMID:27706847 Structurally diverse dehydroshikimate dehydratase variants participate in microbial quinate catabolism. |
| GO:0019633 shikimate catabolic process | ISS PMID:27706847 Structurally diverse dehydroshikimate dehydratase variants p... | ACCEPT | Summary: Core biological process - QuiC1 participates in shikimate degradation pathway Reason: QuiC1 processes 3-dehydroshikimate, a key intermediate in shikimate catabolism, enabling further degradation through protocatechuate. Supporting Evidence: PMID:27706847 Structurally diverse dehydroshikimate dehydratase variants participate in microbial quinate catabolism. |
| GO:0046565 3-dehydroshikimate dehydratase activity | IDA PMID:27706847 Structurally diverse dehydroshikimate dehydratase variants p... | ACCEPT | Summary: Experimentally validated molecular function with detailed kinetic characterization - preferred over IEA evidence Reason: This represents the same function as the earlier IEA annotation but with stronger experimental evidence (IDA) from biochemical characterization. Supporting Evidence: PMID:27706847 Structurally diverse dehydroshikimate dehydratase variants participate in microbial quinate catabolism. |
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Download this section (compressed HTML)Q: What is the evolutionary origin of the two-domain architecture in QuiC1-type dehydroshikimate dehydratases?
Suggested experts: Enzyme evolution specialists, Structural biologists, Comparative genomics researchers
Q: How does the C-terminal domain enhance DSD activity without exhibiting dioxygenase function?
Suggested experts: Enzyme mechanism researchers, Protein domain specialists, Biochemical engineers
Q: Can QuiC1 be optimized for industrial protocatechuate production through protein engineering?
Suggested experts: Metabolic engineers, Protein engineers, Industrial biotechnology specialists
Q: What are the physiological roles of different DSD variants in Pseudomonas metabolism?
Suggested experts: Bacterial metabolism researchers, Systems biology specialists, Environmental microbiologists
Experiment: Create N-terminal and C-terminal domain deletion mutants to determine individual domain contributions to catalytic activity and stability.
Type: Domain deletion analysis
Experiment: Systematic analysis of catalytic activity with different divalent metal cations to optimize enzyme performance for biotechnological applications.
Type: Metal cofactor specificity analysis
Experiment: Compare QuiC1 structure with other DSD variants to understand evolutionary relationships and structure-function determinants.
Type: Comparative structural analysis
Experiment: Engineer QuiC1 expression in heterologous hosts for enhanced protocatechuate production from renewable feedstocks.
Type: Metabolic pathway engineering
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