Marchi, M. | Search bioRxiv

bioRxiv2023

COQ4 is required for the oxidative decarboxylation of the C1 carbon of Coenzyme Q in eukaryotic cells

Coenzyme Q (CoQ) is a redox lipid that fulfills critical functions in cellular bioenergetics and homeostasis. CoQ is synthesized by a multi-step pathway that involves several COQ proteins. Two steps of the eukaryotic pathway, the decarboxylation and hydroxylation of position C1, have remained uncharacterized. Here, we provide evidence that these two reactions occur in a single oxidative decarboxylation step catalyzed by COQ4. We demonstrate that COQ4 complements an Escherichia coli strain deficient for C1 decarboxylation and hydroxylation and that COQ4 displays oxidative decarboxylation activity in the non-CoQ producer Corynebacterium glutamicum. Overall, our results substantiate that COQ4 contributes to CoQ biosynthesis, not only via its previously proposed structural role, but also via oxidative decarboxylation of CoQ precursors. These findings fill a major gap in the knowledge of eukaryotic CoQ biosynthesis, and shed new light on the pathophysiology of human primary CoQ deficiency due to COQ4 mutations.

biochemistry↗

bioRxiv2023

Germination timing under climate change: warmer springs favor early germination of range-wide cork oak populations

Climate change is favoring the northward shift of Mediterranean species which are expanding their ranges at their leading edges, becoming natural candidates for increasing forest biodiversity in these regions. However, current knowledge on tree populations responses to climate change is mostly based on adult trees, even if tree early developmental stages are far more sensitive to climate and tightly linked to fitness. To fill this knowledge gap, we investigated the potential adaptation of cork oak range-wide populations to increasing spring temperature in germination and post-germination traits. We sowed 701 acorns from 11 populations at 15, 20 and 25{degrees}C, monitored germination daily and measured post-germination traits. We model germination timing through Coxs proportional-hazards models, assess populations adaptation to spring temperature transfer distances and quantify the effect of acorn mass and storage duration on all considered traits with fixed-effects models. We predict germination and post-germination climate niches under current and RCP 8.5 2080 scenarios. Large differences in germination timing are due to both the population origin and temperature treatment; germination and survival rates showed a sub-optimality towards warmer-than-origin temperatures and heavier acorns produced faster growing seedlings. The timing of germination is the early stage trait most affected by increasing spring temperatures, with germination in 2080 predicted to be 12 days earlier than to date in the northern part of the species range. Warmer spring temperatures will significantly accelerate the germination of other recalcitrant Mediterranean species, which could alter seedlings developmental environment and ultimately populations regeneration and species composition. As such, germination timing should receive more attention by scientists and stakeholders, and should be included in forest vulnerability assessments and assisted migration programs aiming at long-term forest regeneration to adapt forests to climate change.

ecology↗