Glutathione biosynthesis

A reusable two-reaction pathway that converts L-glutamate, L-cysteine, and glycine to glutathione through gamma-L-glutamyl-L-cysteine. The module represents the conserved GshA/GCLC and GshB/GSS reaction roles independently of genomic arrangement or enzyme regulation. Glutathione reduction, conjugation, peroxide detoxification, degradation, and the wider gamma-glutamyl cycle are outside the boundary.

MODULE:glutathione_biosynthesisDRAFTMetabolic Pathwaymodules/glutathione_biosynthesis.yaml
glutathione biosynthetic processGO:0006750
GO:0006750
glutathione biosynthetic process
GO:0006750 provides the biological-process context.
RHEA:13285
glutamate--cysteine ligase reaction
RHEA:13285 defines ATP-dependent formation of gamma-L-glutamyl-L-cysteine from L-glutamate and L-cysteine.
RHEA:13557
glutathione synthetase reaction
RHEA:13557 defines ATP-dependent addition of glycine to gamma-L-glutamyl-L-cysteine to form glutathione.
UniProtKB:Q9CM00
Pasteurella multocida bifunctional glutathione biosynthesis protein GshAB
The reviewed GshAB/GshF record contains both glutamate--cysteine ligase and glutathione synthetase activities, demonstrating a fused implementation of the same two ordered reaction roles.
PMID:16339152
Characterization of the bifunctional gamma-glutamate-cysteine ligase/glutathione synthetase (GshF) of Pasteurella multocida
Recombinant characterization establishes the two-domain GshF fusion as a bifunctional implementation of both ordered glutathione-biosynthesis reactions.
file:human/GCLC/GCLC-ai-review.yaml
Human GCLC gene review
P48506 provides a eukaryotic exemplar for the first catalytic reaction.
PMID:9895302
Overexpression of the regulatory subunit of gamma-glutamylcysteine synthetase in HeLa cells increases gamma-glutamylcysteine synthetase activity and confers drug resistance.
Experimental addition and overexpression of the human regulatory subunit increased GCL activity, supporting its treatment as an accessory modifier rather than a separate catalytic reaction in the pathway.
file:human/GSS/GSS-ai-review.yaml
Human GSS gene review
P48637 provides a eukaryotic exemplar for the second catalytic reaction.
file:modules/glutathione_biosynthesis-deep-research-openscientist.md
OpenScientist research for glutathione biosynthesis
The generic review evaluates the two conserved reaction roles, pathway boundary, family assignments, and lineage-dependent enzyme forms.
file:PSEPK/gshA/gshA-ai-review.yaml
PSEPK gshA gene review
Q88R90 supplies the glutamate--cysteine ligase step.
file:PSEPK/gshB/gshB-ai-review.yaml
PSEPK gshB gene review
Q88D35 supplies the glutathione synthetase step.
3Nodes
2Parts
0Variant Sets
0Variants
2Annotons
1Connections

Derived QC

Recommended-field compliance

100.0% recommended fields populated

All recommended fields populated.

Module deep research

✓ present

  • glutathione_biosynthesis-deep-research-openscientist.md (openscientist)

Leaf nodes lacking representative members

✓ every leaf node grounds to a representative protein.

Template conformance

✓ every declared conforms_to bundle matches its template motif.

Gene-review completeness (4/7 grounded genes reviewed)

4 complete review(s) · 2 with deep research · 3 missing review · 2 reviewed but lacking deep research

Gene Review Complete Deep research
GCLC P48506 ✓ ✓ ✓
gshA Q88R90 ✓ ✓ ✗
gshB Q88D35 ✓ ✓ ✗
GSS P48637 ✓ ✓ ✓
Escherichia coli K-12 GshB P04425 ✗ — —
Escherichia coli K-12 GshA P0A6W9 ✗ — —
Pasteurella multocida GshAB/GshF Q9CM00 ✗ — —

Details

Glutathione biosynthesisMetabolic Pathwayglutathione_biosynthesis
glutathione biosynthetic processGO:0006750

Exact bacterial and human UniProt exemplars delimit both reaction roles across prokaryotic GshA/GshB and eukaryotic GCLC/GSS families. The narrow subfamilies are used instead of parent families that include ligases with other substrates. The same reviewed GshAB/GshF exemplar appears under both leaf activities because a single bifunctional polypeptide can implement both ordered reactions; it does not collapse the pathway into one biological step. Mammalian GCLM can modify GCLC kinetics but is not a third catalytic reaction and is therefore not a required module part. Type 2/YbdK-family ligases are not an additional required step unless organism-specific physiological evidence establishes that they implement the first reaction. No molecular function or location is duplicated at module level, and no ancestral PTN node is asserted without verified PAINT IBD evidence.

Connections

GshA/GCLC supplies gamma-L-glutamyl-L-cysteine to GshB/GSS.
Part 1: gamma-L-glutamyl-L-cysteine formation
Glutamate--cysteine ligaseReactionglutamate_cysteine_ligase_step

Annotons

Glutamate--cysteine ligase
gshA_activity
Participant: Family: glutamate--cysteine ligases
Family:
glutamate--cysteine ligases
Representative Members: PSEPK GshAUniProtKB:Q88R90 Escherichia coli K-12 GshAUniProtKB:P0A6W9 Human GCLCUniProtKB:P48506 Pasteurella multocida GshAB/GshFUniProtKB:Q9CM00

Function

glutamate-cysteine ligase activityGO:0004357
Substrates: L-glutamate L-cysteine ATP
Products: gamma-L-glutamyl-L-cysteine ADP phosphate proton

Forms the gamma-glutamyl peptide bond in the first committed glutathione-biosynthesis reaction.

Part 2: glutathione formation
Glutathione synthetaseReactionglutathione_synthetase_step

Annotons

Glutathione synthetase
gshB_activity
Participant: Family: glutathione-forming ATP-grasp domains
Family:
glutathione-forming ATP-grasp domains
Representative Members: PSEPK GshBUniProtKB:Q88D35 Escherichia coli K-12 GshBUniProtKB:P04425 Human GSSUniProtKB:P48637 Pasteurella multocida GshAB/GshFUniProtKB:Q9CM00

Function

glutathione synthase activityGO:0004363
Substrates: gamma-L-glutamyl-L-cysteine glycine ATP
Products: glutathione ADP phosphate proton

Adds glycine to gamma-L-glutamyl-L-cysteine to complete glutathione synthesis.