Disentangling the role of extracellular polysaccharides in desiccation tolerance in lichen-forming microalgae. First evidence of sulfated polysaccharides and ancient sulfotransferase genes

Autor(es)

Gonzalez-Hourcade, Maria ^[1] ; del Campo, Eva M. ^[1] ; Braga, Marcia R. ^[2] ; Salgado, Antonio ^[3] ; Casano, Leonardo M. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Alcala De Henares, Dept Life Sci, Madrid 28871 - Spain

^[2] Inst Bot, Dept Plant Physiol & Biochem, BR-04301012 Sao Paulo, SP - Brazil

^[3] Univ Alcala De Henares, Fac Pharm, Ctr Espectroscopia RMN CERMN, Madrid 28805 - Spain

• Tipo de documento: Artigo Científico
• Fonte: ENVIRONMENTAL MICROBIOLOGY; v. 22, n. 8 MAY 2020.
• Citações Web of Science: 0

Resumo

Trebouxia sp. TR9 and Coccomyxa simplex are desiccation-tolerant microalgae with flexible cell walls, which undergo species-specific remodelling during dehydration-rehydration (D/R) due to their distinct ultrastructure and biochemical composition. Here, we tested the hypothesis that extracellular polysaccharides excreted by each microalga could be quantitatively and/or qualitatively modified by D/R. Extracellular polysaccharides were analysed by size exclusion and anion exchange chromatography, specific stains after gel electrophoresis and gas chromatography/mass spectrometry of trimethylsilyl derivatives (to determine their monosaccharide composition). The structure of a TR9-sulfated polymer was deduced from nuclear magnetic resonance (NMR) analyses. In addition, sugar-sulfotransferase encoding genes were identified in both microalgae, and their expression was measured by RT-qPCR. D/R did not alter the polydispersed profile of extracellular polysaccharides in either microalga but did induce quantitative changes in several peaks. Furthermore, medium-low-sized uronic acid-containing polysaccharides were almost completely substituted by higher molecular mass carbohydrates after D/R. Sulfated polysaccharide(s) were detected, for the first time, in the extracellular polymeric substances of both microalgae, but only increased significantly in TR9 after cyclic D/R, which induced a sugar-sulfotransferase gene and accumulated sulfated ss-D-galactofuranan(s). Biochemical remodelling of extracellular polysaccharides in aeroterrestrial desiccation-tolerant microalgae is species-specific and seems to play a role in the response to changes in environmental water availability. (AU)

• Processo FAPESP: 17/50341-0 - Desafios para conservação da biodiversidade frente às mudanças climáticas, poluição e uso e ocupação do solo (PDIp)
• Beneficiário: Luiz Mauro Barbosa
• Modalidade de apoio: Auxílio à Pesquisa - Programa Modernização de Institutos Estaduais de Pesquisa