What this entity is
Canonical name: Leucine. 1
Known aliases: No aliases were reported in the source document. 1
Stable external identifier: No stable external identifier was reported in the source document. 1
Leucine is an amino acid whose community biosynthetic pathway completeness was compared with ambient metabolite intensity using integrated NMDC community data and GTDB pangenome pathway records. 1
Evidence from community metabolomics and pangenomes
Community leucine-biosynthesis completeness was negatively correlated with ambient leucine metabolite intensity, with Spearman r = −0.390, q = 0.022, and n = 62. 1 The leucine result was one of two amino-acid pathway associations that remained significant after Benjamini-Hochberg false-discovery-rate correction at q < 0.05; the other was arginine biosynthesis. 1
The finding supports a weak but consistent community-scale Black Queen Hypothesis signal, in which greater community biosynthetic completeness is associated with lower ambient metabolite intensity, although the study did not establish that leucine biosynthesis was actively expressed. 1 Leucine was reported to require 37 ATP equivalents for biosynthesis, which the report offered as a possible energetic explanation for the negative association. 1
The leucine correlation strengthened from r = −0.326 to r = −0.390, and its q value changed from 0.045 to 0.022, after correction of an isoleucine/leucine compound-mapping collision. 1 All 62 leucine samples came from one NMDC study, which contributed 125 of 131 samples in the pathway–metabolomics dataset. 1 The report states that the leucine result was therefore not subject to cross-study LC-MS protocol heterogeneity within those 62 samples, although replication across additional studies remains necessary. 1
A separate species-scale analysis found all-gene leucine-biosynthesis completeness of 0.614 versus core-only completeness of 0.468, an exact gap of 0.146. 2 This refines the community-scale result by showing that leucine pathway potential can depend partly on genes outside the universally conserved core, consistent with accessory-dependent metabolic capacity. 2 The distribution is consistent with Black Queen dynamics and a potential basis for community sharing of leucine biosynthetic capacity, but it does not itself demonstrate metabolite exchange. 2
Interpretation and limitations
The analysis used GapMind pathway completeness as genomic potential rather than as evidence that leucine biosynthesis was active in the sampled communities. 1 The accessory-dependent completeness result supports retaining this distinction: genomic pathway completeness does not by itself establish expression, dependency, or metabolite exchange. 2
Abiotic measurements for pH, temperature, and total organic carbon were unavailable because all were NaN in the 174-sample analysis matrix, so partial correlations controlling for environmental gradients could not be performed. 1 The leucine association therefore remains compatible with confounding by unmeasured abiotic conditions, community composition, or metabolomics variation. 1
Metatranscriptomic data paired with metabolomics would be needed to test whether expressed leucine-biosynthesis completeness correlates more strongly with ambient leucine pools. 1
Related pages
This entity connects to multi-omics-integration, which covers the integration of community taxonomy, pangenome pathway potential, and metabolomics used in the study. 1
It also connects to metabolic-model-gapfilling, because the study extended GapMind pathway-completeness analysis from species-level annotation to community-weighted metabolic potential. 1 The species-scale completeness comparison is summarized in Metabolic Capability vs Dependency. 2
The negative association is relevant to condition-specific-fitness as an environmental-metabolism comparison involving pathway completeness and metabolite availability. 1
See the source summary at Community Metabolic Ecology via NMDC × Pangenome Integration. 1