RESUMO
Halotolerant species are adapted to dealing continually with hyperosmotic environments, having evolved strategies that are uncommon in other organisms. The HOG pathway is the master system that regulates the cellular adaptation under these conditions; nevertheless, apart from the importance of Debaryomyces hansenii as an organism representative of the halotolerant class, its HOG1 pathway has been poorly studied, due to the difficulty of applying conventional recombinant DNA technology. Here we describe for the first time the phenotypic characterisation of a null HOG1 mutant of D. hansenii. Dhhog1Δ strain was found moderately resistant to 1 M NaCl and sensitive to higher concentrations. Under hyperosmotic shock, DhHog1 fully upregulated transcription of DhSTL1 and partially upregulated that of DhGPD1. High osmotic stress lead to long-term inner glycerol accumulation that was partially dependent on DhHog1. These observations indicated that the HOG pathway is required for survival under high external osmolarity but dispensable under low and mid-osmotic conditions. It was also found that DhHog1 can regulate response to alkali stress during hyperosmotic conditions and that it plays a role in oxidative and endoplasmic reticulum stress. Taken together, these results provide new insight into the contribution of this MAPK in halotolerance of this yeast.
Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas de Membrana Transportadoras/genética , Osmorregulação/genética , Proteínas de Saccharomyces cerevisiae/genética , Saccharomycetales/genética , Álcalis/efeitos adversos , Regulação Fúngica da Expressão Gênica , Glicerol/metabolismo , Pressão Osmótica/fisiologia , Fosforilação , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomycetales/metabolismo , Saccharomycetales/fisiologia , Transdução de Sinais/genéticaRESUMO
Debaryomyces hansenii is a halotolerant yeast with a high biotechnological potential, particularly in the food industry. However, research in this yeast is limited by its molecular peculiarities. In this review we summarize the state of the art of research in this microorganisms, describing both pros and cons. We discuss (i) its halotolerance, (ii) the molecular factors involved in saline and osmotic stress, (iii) its high gene density and ambiguous CUG decoding, and (iv) its biotechnological and medical interests. We trust that all the bottlenecks in its study will soon be overcome and D. hansenii will become a fundamental organism for food biotechnological processes. Copyright © 2016 John Wiley & Sons, Ltd.