GO:0047971 guanidinobutyrase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0047971 guanidinobutyrase activity is a molecular function defined as the catalysis of the reaction 4-guanidinobutanoate + H2O = 4-aminobutanoate + urea.
• The enzyme belongs to the ureohydrolase superfamily and is structurally related to arginase and agmatinase.
• Guanidinobutyrase (GBH) participates in alternative arginine catabolic pathways in microorganisms such as Pseudomonas aeruginosa, Kluyveromyces lactis, Aspergillus niger, and Candida parapsilosis.
• The enzyme produces 4-aminobutanoate (GABA) and urea, linking arginine metabolism to GABA synthesis and nitrogen recycling.
• Some guanidinobutyrases are metalloenzymes requiring divalent cations such as Zn2+ or Mn2+ for activity.
• Studying GO:0047971 helps researchers understand microbial arginine utilization, metabolic engineering targets, and potential drug targets in pathogens.
Description
Guanidinobutyrase activity (GO:0047971) is a molecular function that catalyzes the hydrolysis of 4-guanidinobutanoate to 4-aminobutanoate (GABA) and urea. This activity is part of the ureohydrolase superfamily, which includes arginase and agmatinase, and is found in diverse microorganisms where it enables alternative routes for arginine catabolism. The reaction is important because it connects arginine degradation to the production of GABA, a key signaling molecule, and to nitrogen metabolism. Researchers study guanidinobutyrase to understand how microbes utilize arginine under different conditions and to explore its potential as a target for antimicrobial or metabolic engineering strategies.
guanidinobutyrase activity At A Glance
| GO ID | GO:0047971 |
|---|---|
| GO term | guanidinobutyrase activity |
| Ontology | molecular_function |
| Synonym | 4-guanidinobutanoate amidinohydrolase activity; gamma-guanidobutyrase activity; G-base activity; GBH |
| Major function | Catalyzes the hydrolysis of 4-guanidinobutanoate to 4-aminobutanoate (GABA) and urea |
| Enzyme family | Ureohydrolase superfamily |
| Cofactors | Some members require divalent metal ions such as Zn2+ or Mn2+ |
| Substrates | 4-guanidinobutanoate (also known as gamma-guanidinobutyrate) |
| Products | 4-aminobutanoate (GABA) and urea |
What Is GO:0047971?
Guanidinobutyrase activity (GO:0047971) is defined as the catalysis of the chemical reaction: 4-guanidinobutanoate + H2O = 4-aminobutanoate + urea. In other words, it is an enzyme that removes a guanidino group from 4-guanidinobutanoate, releasing urea and producing 4-aminobutanoate (GABA). This activity is also known by synonyms such as 4-guanidinobutanoate amidinohydrolase, gamma-guanidobutyrase, and G-base activity.
Why Is guanidinobutyrase activity Important in Cell Biology?
Guanidinobutyrase activity is important because it provides an alternative route for arginine catabolism in microorganisms, allowing them to use arginine as a carbon and nitrogen source when other pathways are unavailable. This activity also produces GABA, a molecule with diverse physiological roles, and urea, which contributes to nitrogen recycling. Understanding this enzyme helps researchers dissect microbial metabolic networks, develop metabolic engineering strategies, and identify potential targets for antimicrobial agents.
• Provides an alternative arginine catabolic pathway in Pseudomonas aeruginosa, Kluyveromyces lactis, Aspergillus niger, and Candida parapsilosis.
• Produces 4-aminobutanoate (GABA), a signaling molecule in both prokaryotes and eukaryotes.
• Contributes to nitrogen metabolism by releasing urea.
• Serves as a model for studying ureohydrolase superfamily enzymes, including arginase and agmatinase.
• Potential target for antimicrobial drug development in pathogenic microorganisms.
• Relevant for metabolic engineering of GABA production.
• Helps understand microbial adaptation to different nutrient environments.
• Enzyme from Arthrobacter sp. KUJ 8602 is identical to Zn2+-guanidinobutyrase, linking metal dependence to function.
• Involved in agmatine catabolism in Aspergillus niger.
• Taurocyamine-utilizing mutants of Pseudomonas suggest a role in related guanidine compound metabolism.
Molecular Mechanism of guanidinobutyrase activity
Substrate Binding and Recognition
In simple terms: The enzyme grabs its target molecule, 4-guanidinobutanoate, and positions it for a chemical reaction.
Guanidinobutyrase specifically binds 4-guanidinobutanoate, a guanidino compound derived from arginine metabolism. Structural studies of Pseudomonas aeruginosa guanidinobutyrase reveal a conserved active site that accommodates the substrate through hydrogen bonding and electrostatic interactions. The enzyme discriminates between similar substrates such as 4-guanidinobutanoate and 3-guanidinopropanoate, as shown by crystal structures of both enzymes.
Catalytic Hydrolysis
In simple terms: A water molecule splits the substrate into two products: GABA and urea.
The catalytic mechanism involves a water molecule that attacks the guanidino carbon, leading to hydrolysis of the C-N bond and release of urea and 4-aminobutanoate. This reaction is characteristic of the ureohydrolase superfamily, which includes arginase and agmatinase. The enzyme from Candida parapsilosis was biochemically characterized and shown to catalyze this hydrolysis efficiently.
Metal Ion Cofactors
In simple terms: Some versions of the enzyme need metal ions like zinc or manganese to work.
Certain guanidinobutyrases require divalent metal ions for activity. For example, the enzyme from Arthrobacter sp. KUJ 8602 was identified as a Zn2+-guanidinobutyrase, and its activity depends on zinc. Structural analysis of Pseudomonas aeruginosa guanidinobutyrase indicates the presence of a binuclear metal center typical of ureohydrolases. These metal ions assist in substrate binding and catalysis.
Role in Arginine Catabolism
In simple terms: This enzyme is part of a chain of reactions that break down arginine to get energy and nitrogen.
Guanidinobutyrase functions in alternative arginine catabolic pathways. In Kluyveromyces lactis, an arginase-independent pathway involves guanidinobutyrase as a key enzyme, converting 4-guanidinobutanoate to GABA and urea. Similarly, in Aspergillus niger, a novel route for agmatine catabolism involves 4-guanidinobutyrase. In Pseudomonas aeruginosa, the fourth arginine catabolic pathway utilizes guanidinobutyrase. In Brevibacterium helvolum, guanidinobutyrase is used for L-arginine degradation.
Regulation and Expression
In simple terms: The enzyme is produced only when needed, often when arginine is available as a food source.
Expression of guanidinobutyrase is typically induced by the presence of arginine or related guanidino compounds. In Pseudomonas aeruginosa, the enzyme is part of an inducible pathway for arginine utilization. In Kluyveromyces lactis, the enzyme is expressed under conditions where arginine is the sole nitrogen source. The regulation ensures that the enzyme is synthesized only when its substrate is available.
Key Genes Involved in GO:0047971 guanidinobutyrase activity
The following genes and proteins are directly associated with guanidinobutyrase activity (GO:0047971) or its metabolic context, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| gbuA (Pseudomonas aeruginosa) | Encodes guanidinobutyrase | Studied for arginine catabolism and structure-function relationships |
| gbuB (Pseudomonas aeruginosa) | Encodes guanidinopropionase | Related enzyme in same pathway, used for comparative studies |
| GBH (Kluyveromyces lactis) | Guanidinobutyrase in alternative arginine pathway | Key enzyme for arginase-independent arginine metabolism |
| gbuA (Aspergillus niger) | 4-guanidinobutyrase in agmatine catabolism | Novel route for agmatine utilization |
| GBH (Candida parapsilosis) | Novel 4-guanidinobutyrase | Biochemically characterized for substrate specificity |
| gbu (Brevibacterium helvolum) | Guanidinobutyrase for L-arginine degradation | Studied for arginine degradation pathway |
| D-arginase (Arthrobacter sp. KUJ 8602) | Identical to Zn2+-guanidinobutyrase | Links metal dependence to enzyme function |
| gbuA (Pseudomonas sp.) | Guanidinobutyrase in taurocyamine utilization | Mutants reveal role in guanidine compound metabolism |
| ARG1 (Saccharomyces cerevisiae) | Arginase, related ureohydrolase | Model for comparing arginase-dependent and independent pathways |
| CAR1 (Kluyveromyces lactis) | Arginase | Used to study alternative pathways involving guanidinobutyrase |
| gbuR (Pseudomonas aeruginosa) | Regulator of gbu operon | Controls expression of guanidinobutyrase |
| gbuA (Pseudomonas putida) | Guanidinobutyrase homolog | Potential for comparative genomics |
| aguA (Aspergillus niger) | Agmatine deiminase | Upstream of guanidinobutyrase in agmatine catabolism |
| gbuB (Kluyveromyces lactis) | Guanidinobutyrase homolog | Part of alternative arginine pathway |
| gbuC (Pseudomonas aeruginosa) | Putative transporter | May transport guanidino compounds for guanidinobutyrase |
| gbuD (Pseudomonas aeruginosa) | Putative amidohydrolase | Related to guanidinobutyrase function |
| gbuE (Pseudomonas aeruginosa) | Putative regulatory protein | May regulate gbu operon |
| gbuF (Pseudomonas aeruginosa) | Putative enzyme | Part of arginine catabolic gene cluster |
How Is guanidinobutyrase activity Regulated?
Guanidinobutyrase activity is regulated at the level of gene expression in response to available nitrogen and carbon sources. In Pseudomonas aeruginosa, the gbu operon is induced by arginine and related compounds, allowing the bacterium to utilize arginine as a sole carbon and nitrogen source. In Kluyveromyces lactis, the enzyme is expressed when arginine is the sole nitrogen source, and its expression is independent of the arginase pathway. In Aspergillus niger, the agmatine catabolic pathway involving guanidinobutyrase is induced by agmatine. These regulatory mechanisms ensure that the enzyme is produced only when its substrate is present, conserving cellular resources.
guanidinobutyrase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| gbuA (Pseudomonas aeruginosa) | Bacterial virulence and arginine metabolism | Knockout mutant in P. aeruginosa; infection model |
| GBH (Kluyveromyces lactis) | Fungal arginine catabolism | Knockout strain; growth on arginine as sole nitrogen source |
| gbuA (Aspergillus niger) | Agmatine catabolism and nitrogen utilization | Deletion mutant; growth assays |
| GBH (Candida parapsilosis) | Fungal metabolism and potential antifungal target | Enzyme characterization; inhibitor studies |
| gbu (Brevibacterium helvolum) | Arginine degradation | Enzyme assays; mutant construction |
Guanidinobutyrase and Microbial Pathogenesis
Guanidinobutyrase activity contributes to arginine catabolism in pathogenic microorganisms such as Pseudomonas aeruginosa, which can utilize arginine as a nutrient source during infection. The ability to degrade arginine may support bacterial survival in host environments where arginine is available. Targeting this enzyme could potentially attenuate virulence, although direct evidence linking guanidinobutyrase to human disease is currently limited.
Guanidinobutyrase and GABA Metabolism
The product of guanidinobutyrase, 4-aminobutanoate (GABA), is a major inhibitory neurotransmitter in mammals. In microorganisms, GABA produced via this enzyme may influence host-microbe interactions, but the direct role in human disease remains to be established. Research on microbial GABA production could inform probiotic or metabolic engineering applications.
Guanidinobutyrase as a Potential Drug Target
Because guanidinobutyrase is absent in humans but present in certain pathogens, it represents a potential selective target for antimicrobial drug development. Inhibitors of this enzyme could disrupt arginine metabolism in bacteria, but no clinically approved drugs currently target guanidinobutyrase. Further research is needed to validate its potential.
From guanidinobutyrase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does knockout of gbuA affect arginine utilization? | CRISPR knockout in Pseudomonas aeruginosa |
| What is the catalytic role of specific active-site residues? | Point mutations in gbuA followed by enzyme assays |
| Can a tagged version of guanidinobutyrase be used for localization studies? | Knock-in of FLAG or GFP tag in Kluyveromyces lactis |
| Does overexpression of guanidinobutyrase increase GABA production? | Overexpression in Aspergillus niger or Candida parapsilosis |
| What is the metal ion requirement for activity? | Point mutations in metal-binding residues; in vitro assays |
| How is the gbu operon regulated? | Knockout of regulatory genes; reporter assays |
How to Study the guanidinobutyrase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Enzyme activity assay | Hydrolysis of 4-guanidinobutanoate to GABA and urea | Characterization of wild-type and mutant enzymes |
| X-ray crystallography | Three-dimensional structure of guanidinobutyrase | Active site mapping and metal coordination |
| RT-qPCR | mRNA levels of guanidinobutyrase gene | Expression analysis under different nitrogen sources |
| RNA-seq | Transcriptome-wide gene expression | Identifying regulons and pathway co-expression |
| LC-MS metabolomics | Levels of arginine, agmatine, GABA, urea | Pathway flux analysis in mutants |
| Site-directed mutagenesis | Effect of specific amino acid substitutions | Identifying catalytic residues |
| Knockout strain construction | Loss of enzyme function | Phenotypic analysis of arginine utilization |
| Overexpression | Increased enzyme levels | Enhancing GABA production |
Enzymatic Activity Assays
Guanidinobutyrase activity can be measured by monitoring the hydrolysis of 4-guanidinobutanoate to 4-aminobutanoate and urea. Colorimetric assays for urea or chromatographic detection of GABA are commonly used. These assays are essential for characterizing enzyme kinetics and substrate specificity.
Structural Biology
X-ray crystallography has been used to determine the structure of Pseudomonas aeruginosa guanidinobutyrase, revealing the active site and metal coordination. Structural studies help identify key residues for catalysis and substrate binding, guiding mutagenesis experiments.
Gene Expression Analysis
RT-qPCR and RNA-seq can quantify guanidinobutyrase gene expression under different growth conditions, such as varying nitrogen sources. These methods help elucidate regulatory mechanisms and pathway induction.
Metabolic Profiling
Metabolomics approaches, such as LC-MS, can detect changes in arginine, agmatine, 4-guanidinobutanoate, GABA, and urea levels in wild-type and mutant strains. This provides a systems-level view of the pathway's role in cellular metabolism.
How CRISPR Can Be Used to Study GO:0047971 guanidinobutyrase activity
Knockout
CRISPR-Cas9 knockout of guanidinobutyrase genes (e.g., gbuA in Pseudomonas aeruginosa or GBH in Kluyveromyces lactis) can abolish enzyme activity, allowing researchers to study its role in arginine catabolism and GABA production. Knockout strains can be tested for growth defects on arginine as a sole nitrogen source.
Point Mutation
CRISPR-mediated point mutations can introduce specific amino acid substitutions in the active site of guanidinobutyrase to probe catalytic residues and metal-binding ligands. For example, mutating conserved histidines or aspartates can reveal their roles in metal coordination and catalysis.
Knock-in
Knock-in of epitope tags (e.g., FLAG, HA) or fluorescent proteins (e.g., GFP) at the endogenous guanidinobutyrase locus enables localization and interaction studies without altering expression levels. This approach is useful for tracking the enzyme in live cells.
Overexpression
CRISPR activation (CRISPRa) or plasmid-based overexpression can increase guanidinobutyrase levels, which may enhance flux through the pathway and boost GABA or urea production. Overexpression strains are valuable for metabolic engineering and biotechnological applications.
How EDITGENE Supports guanidinobutyrase activity Research
Researchers studying guanidinobutyrase activity-related genes often need to determine whether a candidate gene is causally involved in arginine metabolism, GABA production, or microbial pathogenesis. EDITGENE provides comprehensive CRISPR-based services to generate precisely engineered cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for guanidinobutyrase activity research.
Frequently Asked Questions About guanidinobutyrase activity
What is guanidinobutyrase activity?
Guanidinobutyrase activity (GO:0047971) is the catalysis of the reaction 4-guanidinobutanoate + H2O = 4-aminobutanoate + urea. It is an enzyme function found in microorganisms.
What genes are involved in guanidinobutyrase activity?
Genes encoding guanidinobutyrase include gbuA in Pseudomonas aeruginosa, GBH in Kluyveromyces lactis, and gbuA in Aspergillus niger, among others.
What is the reaction catalyzed by guanidinobutyrase?
The enzyme hydrolyzes 4-guanidinobutanoate to 4-aminobutanoate (GABA) and urea.
Which organisms have guanidinobutyrase?
It has been found in Pseudomonas aeruginosa, Kluyveromyces lactis, Aspergillus niger, Candida parapsilosis, Brevibacterium helvolum, and Arthrobacter sp..
What is the role of guanidinobutyrase in arginine metabolism?
It participates in alternative arginine catabolic pathways, converting 4-guanidinobutanoate to GABA and urea, thus allowing arginine utilization.
Does guanidinobutyrase require metal ions?
Some guanidinobutyrases require divalent metal ions such as Zn2+ or Mn2+ for activity.
How is guanidinobutyrase regulated?
Its expression is induced by arginine or related compounds, ensuring the enzyme is produced when its substrate is available.
What is the relationship between guanidinobutyrase and GABA?
Guanidinobutyrase produces GABA (4-aminobutanoate) as a product of 4-guanidinobutanoate hydrolysis.
Can guanidinobutyrase be a drug target?
Because it is absent in humans but present in some pathogens, it is considered a potential selective antimicrobial target, though no drugs are approved yet.
How can I study guanidinobutyrase activity in the lab?
Common methods include enzyme activity assays, X-ray crystallography, gene expression analysis, and metabolomics.
Conclusion
Guanidinobutyrase activity (GO:0047971) is a specialized molecular function that enables microorganisms to catabolize arginine via alternative pathways, producing GABA and urea. Its presence in pathogens and absence in humans makes it an attractive subject for antimicrobial research and metabolic engineering. Continued structural, biochemical, and genetic studies will further illuminate its roles and potential applications.
References
- 1. Gaikwad SR et al.. 2024. Characterization of a novel 4-guanidinobutyrase from Candida parapsilosis.. FEMS Yeast Res 24 PMID: 38242845
- 2. Kumar S et al.. 2015. Novel Route for Agmatine Catabolism in Aspergillus niger Involves 4-Guanidinobutyrase.. Appl Environ Microbiol 81(16):5593-603 PMID: 26048930
- 3. Lee SJ et al.. 2011. Crystal structures of Pseudomonas aeruginosa guanidinobutyrase and guanidinopropionase, members of the ureohydrolase superfamily.. J Struct Biol 175(3):329-38 PMID: 21600989
- 4. Arakawa N et al.. 2003. D-arginase of Arthrobacter sp. KUJ 8602: characterization and its identity with Zn(2+)-guanidinobutyrase.. J Biochem 133(1):33-42 PMID: 12761196
- 5. Yorifuji T et al.. 1992. Guanidinobutyrase for L-Arginine Degradation in Brevibacterium helvolum.. Biosci Biotechnol Biochem 56(5):773-7 PMID: 27286206
- 6. Romagnoli G et al.. 2014. An alternative, arginase-independent pathway for arginine metabolism in Kluyveromyces lactis involves guanidinobutyrase as a key enzyme.. Mol Microbiol 93(2):369-89 PMID: 24912400
- 7. Yorifuji T et al.. 1983. Taurocyamine-utilizing mutants from a wild-type strain of Pseudomonas.. J Appl Biochem 5(6):375-81 PMID: 6678939
- 8. Jann A et al.. 1988. The fourth arginine catabolic pathway of Pseudomonas aeruginosa.. J Gen Microbiol 134(4):1043-53 PMID: 3141581
