title: Unraveling the genetic basis of xylose consumption in engineered Saccharomyces cerevisiae strains.
abstract: The development of biocatalysts capable of fermenting xylose, a five-carbon sugar abundant in lignocellulosic biomass, is a key step to achieve a viable production of second-generation ethanol. In this work, a robust industrial strain of Saccharomyces cerevisiae was modified by the addition of essential genes for pentose metabolism. Subsequently, taken through cycles of adaptive evolution with selection for optimal xylose utilization, strains could efficiently convert xylose to ethanol with a yield of about 0.46 g ethanol/g xylose. Though evolved independently, two strains carried shared mutations: amplification of the xylose isomerase gene and inactivation of ISU1, a gene encoding a scaffold protein involved in the assembly of iron-sulfur clusters. In addition, one of evolved strains carried a mutation in SSK2, a member of MAPKKK signaling pathway. In validation experiments, mutating ISU1 or SSK2 improved the ability to metabolize xylose of yeast cells without adaptive evolution, suggesting that these genes are key players in a regulatory network for xylose fermentation. Furthermore, addition of iron ion to the growth media improved xylose fermentation even by non-evolved cells. Our results provide promising new targets for metabolic engineering of C5-yeasts and point to iron as a potential new additive for improvement of second-generation ethanol production.
authors.affiliation: Laboratório de Genômica e Expressão, Departamento de Genética e Evolução, UNICAMP, Campinas, São Paulo 13083-970, Brazil.|GranBio/BioCelere, Campinas, Brazil.
authors.forename: Leandro Vieira
authors.initials: LV
authors.lastname: Dos Santos
authors.affiliation: Laboratório de Genômica e Expressão, Departamento de Genética e Evolução, UNICAMP, Campinas, São Paulo 13083-970, Brazil.
authors.forename: Marcelo Falsarella
authors.initials: MF
authors.lastname: Carazzolle
authors.affiliation: Laboratório de Genômica e Expressão, Departamento de Genética e Evolução, UNICAMP, Campinas, São Paulo 13083-970, Brazil.
authors.forename: Sheila Tiemi
authors.initials: ST
authors.lastname: Nagamatsu
authors.affiliation: Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins-CO, 80523-1618, USA.
authors.forename: Nádia Maria Vieira
authors.initials: NM
authors.lastname: Sampaio
authors.affiliation: GranBio/BioCelere, Campinas, Brazil.
authors.forename: Ludimila Dias
authors.initials: LD
authors.lastname: Almeida
authors.affiliation: GranBio/BioCelere, Campinas, Brazil.
authors.forename: Renan Augusto Siqueira
authors.initials: RA
authors.lastname: Pirolla
authors.affiliation: Laboratório de Genômica e Expressão, Departamento de Genética e Evolução, UNICAMP, Campinas, São Paulo 13083-970, Brazil.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Borelli
authors.affiliation: Laboratório de Genômica e Expressão, Departamento de Genética e Evolução, UNICAMP, Campinas, São Paulo 13083-970, Brazil.
authors.forename: Thamy Lívia Ribeiro
authors.initials: TL
authors.lastname: Corrêa
authors.affiliation: Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins-CO, 80523-1618, USA.
authors.forename: Juan Lucas
authors.initials: JL
authors.lastname: Argueso
authors.affiliation: Laboratório de Genômica e Expressão, Departamento de Genética e Evolução, UNICAMP, Campinas, São Paulo 13083-970, Brazil.|GranBio/BioCelere, Campinas, Brazil.
authors.forename: Gonçalo Amarante Guimarães
authors.initials: GA
authors.lastname: Pereira
mesh_terms: D001483:Base Sequence; D004171:Diploidy; D019143:Evolution, Molecular; D005285:Fermentation / Q000187:drug effects; D005818:Genetic Engineering / Q000379:methods*; D016681:Genome, Fungal; D006579:Heterozygote; D006720:Homozygote; D007501:Iron / Q000494:pharmacology; D059785:Karyotype; D060847:Metabolic Engineering; D009711:Nucleotides / Q000235:genetics; D017354:Point Mutation / Q000235:genetics; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D014170:Transformation, Genetic; D014994:Xylose / Q000378:metabolism*
chemical_list: D009711:Nucleotides; D029701:Saccharomyces cerevisiae Proteins; D014994:Xylose; D007501:Iron