Biology subjects

Nicoll, C. R.

Publications and source records attributed to Nicoll, C. R..

3 recordsLinked to original sources

bioRxiv2026

L-2-hydroxyglutarate recycling is linked to coenzyme Q biosynthesis

The mitochondrial COQ metabolon catalyzes the late stages of the biosynthesis of coenzyme Q, an essential and ubiquitous cofactor. Here, by integrating coevolution, coexpression, colocalization and domain-fusion analyses, we identify L-2-hydroxyglutarate dehydrogenase (L2HGDH) as an integral component of this assembly. By acting in physical proximity to the COQ metabolon, L2HGDH sustains coenzyme Q production by maintaining the biosynthetic intermediates in their catalytically-active reduced state. Consistently, analysis of fibroblasts and urine samples from patients with primary coenzyme Q deficiency displayed marked accumulation of L-2-hydroxyglutarate. Cryo-electron microscopy reveals that L2HGDH forms a stable complex with COQ3 and COQ6, defining a heterotrimeric assembly that organizes catalytic sites on a shared membrane-facing surface thereby enabling localized quinone reduction. Together, these findings identify L2HGDH as a previously unrecognized component of the COQ metabolon, establish a direct link between central carbon metabolism and coenzyme Q biosynthesis, and expand the functional roles of metabolons in coordinating metabolic flux across distinct pathways.

biochemistry↗

bioRxiv2026

COQ8 chaperones coenzyme Q lipid intermediates through ATP-driven structural gating

Coenzyme Q biosynthesis requires the atypical kinase-like COQ8 proteins, whose ATPase activity streamlines the membrane-associated COQ metabolon, yet its molecular mechanism has remained unclear. Taking advantage of the tetrapod ancestral coenzyme Q biosynthetic machinery and liposomes mimicking the inner mitochondrial membrane, we show that COQ8A and COQ8B act as a streamlining factor for the coenzyme Q metabolon by engaging in loose protein-protein interactions and delivering insoluble biosynthetic intermediates. Structural bioinformatics and pathological-variant-driven mutagenesis reveal that coenzyme Q intermediates are recognized via their head-groups in a pocket whose access is gated by long-range conformational changes controlled by ATP hydrolysis. Finally, it is demonstrated that excess coenzyme Q suppresses binding of early-stage intermediates and thereby abolishes the streamlining effect of COQ8 on the metabolon. Together, these results support a model in which COQ8 functions as a biochemical coenzyme Q sensor that tunes coenzyme Q biosynthesis by coupling ATPase-driven intermediate chaperoning with feedback regulation by the final product. TeaserCOQ8 enhances coenzyme Q metabolic flux via ATP hydrolysis-driven chaperoning of biosynthetic intermediates.

biochemistry↗

bioRxiv2025

Complete Enzyme Clustering Enhances Coenzyme Q Biosynthesisvia Substrate Channeling

Metabolons - transient assemblies of sequential metabolic enzymes - facilitate the reactions of multi-step metabolic pathways, yet, how they mechanistically bolster metabolic flux remains unknown. Here, we investigate the molecular determinants of metabolon formation in coenzyme Q (CoQ) biosynthesis using coarse-grained molecular dynamics simulations and biochemical experiments. We show that the COQ metabolon forms at the critical region of a phase transition, where both metabolon clustering and metabolic flux exhibit coordinated sigmoidal responses to changes in protein-protein interaction strength. These complete metabolons enable substrate channeling between sequential enzymes, leading to a crucial enhancement of CoQ production efficiency. Selectively disrupting protein-protein interactions and randomly shuffling the interaction network demonstrate that protein-proximity rather than fine structure of the metabolon clusters is imperative for substrate channeling. Grounded in both experiment and simulation, these findings provide a framework for understanding the organization and function of metabolons across diverse metabolic pathways.

biophysics↗