astB

UniProt ID: O50175
Organism: Pseudomonas aeruginosa PAO1
Review Status: COMPLETE
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Gene Description

AstB (AruB, PA0899) is N2-succinylarginine dihydrolase, the second enzyme of the arginine succinyltransferase (AST) pathway, the main route of aerobic arginine and ornithine utilization in Pseudomonas aeruginosa. It hydrolyses N2-succinylarginine to N2-succinylornithine, ammonia and CO2. The gene lies in the ArgR-controlled aruCFGDB operon with the genes for the succinylornithine transaminase, the two succinyltransferase subunits and the succinylglutamate semialdehyde dehydrogenase. The enzyme belongs to the AstB (succinylarginine dihydrolase) family and is expected to be a cytoplasmic homodimer.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0006525 arginine metabolic process
IEA
GO_REF:0000002 		TOO GENERAL
Summary: InterPro2GO mapping to the general arginine metabolism term.
Reason: True, but GO:0006527 L-arginine catabolic process, accepted in this review, is_a GO:0006525 and entails it.
Supporting Evidence:
PMID:9393691
The aruR, aruC, aruD, aruB, and aruE genes specify the ArgR regulatory protein, N2-succinylornithine 5-aminotransferase, N-succinylglutamate 5-semialdehyde dehydrogenase, N2-succinylarginine dihydrolase, and N-succinylglutamate desuccinylase, respectively
GO:0006527 L-arginine catabolic process
IBA
GO_REF:0000033 		ACCEPT
Summary: IBA from PTN000764516, the PTHR30420 node spanning the AstB dihydrolases and the AstA/AruG succinyltransferases, seeded by E. coli AstB and the three P. aeruginosa AST enzymes.
Reason: Both subfamilies catalyse steps of the AST arginine catabolic pathway, so the process term suits the whole node. Self-seed is expected; the IBD stands without it on E. coli AstB (IMP PMID:9696779).
Supporting Evidence:
PMID:9393691
The aruR, aruC, aruD, aruB, and aruE genes specify the ArgR regulatory protein, N2-succinylornithine 5-aminotransferase, N-succinylglutamate 5-semialdehyde dehydrogenase, N2-succinylarginine dihydrolase, and N-succinylglutamate desuccinylase, respectively
GO:0006527 L-arginine catabolic process
IDA
PMID:16593724
N-Succinylated intermediates in an arginine catabolic pathwa... 		ACCEPT
Summary: PseudoCAP IDA and a seed of PTN000764516. The paper established the AST pathway, including the dihydrolase step, by extract enzyme assays and aru mutants.
Reason: Seed verdict SOUND. The term is correct for AstB, which catalyses step 2 of the pathway; gene assignment is from PMID:9393691. Abstract only.
Supporting Evidence:
PMID:16593724
Enzyme assays with crude P. aeruginosa extracts established the following pathway
PMID:9393691
The aruR, aruC, aruD, aruB, and aruE genes specify the ArgR regulatory protein, N2-succinylornithine 5-aminotransferase, N-succinylglutamate 5-semialdehyde dehydrogenase, N2-succinylarginine dihydrolase, and N-succinylglutamate desuccinylase, respectively
GO:0006527 L-arginine catabolic process
IEA
GO_REF:0000120 		ACCEPT
Summary: Combined automated annotation (UniRule/HAMAP); consistent with the IDA.
Reason: Consistent with the experimental and IBA rows on the same term.
Supporting Evidence:
file:PSEAE/astB/astB-uniprot.txt
MF_01172; AstB
GO:0009015 N-succinylarginine dihydrolase activity
IBA
GO_REF:0000033 		ACCEPT
Summary: IBA from PTN000764516, seeded only by E. coli AstB (IDA PMID:15703173).
Reason: Correct for AstB, an ortholog of the seed in the dihydrolase subfamily (SF2). The node is placed too deep, so the same IBA also reaches the AstA/AruG succinyltransferases; that node-level defect is recorded on astA, not here.
Supporting Evidence:
PMID:9393691
The aruR, aruC, aruD, aruB, and aruE genes specify the ArgR regulatory protein, N2-succinylornithine 5-aminotransferase, N-succinylglutamate 5-semialdehyde dehydrogenase, N2-succinylarginine dihydrolase, and N-succinylglutamate desuccinylase, respectively
file:PSEAE/astB/astB-uniprot.txt
PF04996; AstB
GO:0009015 N-succinylarginine dihydrolase activity
IEA
GO_REF:0000120 		ACCEPT
Summary: Combined automated annotation (InterPro, HAMAP, Rhea); consistent.
Reason: Consistent with the gene assignment in PMID:9393691 and with the IBA row.
Supporting Evidence:
file:PSEAE/astB/astB-uniprot.txt
MF_01172; AstB

Core Functions

N2-succinylarginine dihydrolase, step 2 of the arginine succinyltransferase (AST) pathway of aerobic arginine catabolism.

Molecular Function:
N-succinylarginine dihydrolase activity
Directly Involved In:
L-arginine catabolic process
Supporting Evidence:
  • PMID:9393691
    The aruR, aruC, aruD, aruB, and aruE genes specify the ArgR regulatory protein, N2-succinylornithine 5-aminotransferase, N-succinylglutamate 5-semialdehyde dehydrogenase, N2-succinylarginine dihydrolase, and N-succinylglutamate desuccinylase, respectively
  • file:PSEAE/astB/astB-uniprot.txt
    MF_01172; AstB

References

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Suggested Experiments

Experiment: Purify P. aeruginosa AruB and measure N2-succinylarginine hydrolysis kinetics, confirming the products (N2-succinylornithine, NH3, CO2), since activity has so far been shown only in extracts and for the E. coli ortholog.

📚 Additional Documentation

Notes

(astB-notes.md)

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