Biology subjects

Francois, J. M.

Publications and source records attributed to Francois, J. M..

2 recordsLinked to original sources

bioRxiv2023

Long-term phenotypic and genomic instability of an industrial ethanol-producing and C5-utilizing Saccharomyces cerevisiae strain

The performance of a microbial fermentation for the production of a bio-based product requires long-term robustness and stability of the producer strain. Here, we explored the genetic and metabolic stability of an industrial ethanol-producer Saccharomyces cerevisiae strain that was engineered by chromosomal integration of several copies of transgenes allowing co-fermentation of D-xylose and L-arabinose with glucose. Through sequential batch cultures in controlled bioreactor, it was found that this strain exhibited significant fluctuation of xylose and arabinose consumption starting at 50th generation and onward. Also, clones that have partly or completely lost the ability to assimilate arabinose or xylose were isolated, and this alteration was due to reduced copy number of the transgenes encoding the enzymes of the C5 sugar assimilation. However, subpopulation enriched with low or high RAD52 expression, whose expression level was reported to be proportional to homologous recombination rate did not exhibit defect in C5-sugar assimilation, arguing that other mechanisms may be responsible for copy number variation of transgenes. Overall, this work underscored genetic and metabolic instabilities, which although modest under our conditions, could in the longer term and under more stringent industrial conditions lead to a reduction of production performance.

bioengineering↗

bioRxiv2021

Physiological function of Flo11p domains and the particular role of amyloid core sequences of this adhesin in Saccharomyces cerevisiae

Flocculins are a family of glycosylated proteins that provide yeast cells with several properties such as biofilm formation, flocculation, invasive growth or formation of velum. These proteins are similarly organised with a N-terminal (adhesion) domain, a stalk-like central B-domain with several repeats and a C-terminal sequence carrying a cell wall anchor site. They also contain amyloid {beta}-aggregation-prone sequences whose functional role is still unclear. In this work, we show that Flo11p differs from other flocculins by the presence of unique amyloid-forming sequences, whose the number is critical in the formation of adhesion nanodomains under a physical shear force. Using a genome editing approach to identify the function of domains in Flo11p phenotypes, we show that the formation of cellular aggregates whose density increases with the number of amyloid sequences cannot be attributed to a specific domain of Flo11p. The same is true for plastic adhesion and surface hydrophobicity the intensity of which depends mainly on the abundance of Flo11p on the cell surface. In contrast, the N and C domains of Flo11p are essential for invasive growth in agar, whereas a reduction in the number of repeats of the B domain weakens this phenotype. However, expression of FLO11 alone is not sufficient to trigger this invasion phenotype. Finally, we show that this flocculin contributes to the integrity of the cell wall.

microbiology↗