Carbohydrate Hydrolysis, Transport and the Effect of Glycosylation on the Hot-acid Stability of a Hyperthermoacidophilic Archaeon Sulfolobus solfataricus.

摘要

Extremely thermoacidophilic microbes such as Sulfolobus solfataricus are strict chemoheterotrophs despite their geologic niche. Strain specific differences in genome structure implicated a unique role for one of three endogenous endoglucanases, which promoted the consumption of oligosaccharides including cellohexaose (G6) through cellonanaose (G9). Protein transporters required for cellodextrin uptake were identified through mutagenesis and complementation of an ABC transporter cassette including a putative oligosaccharide binding protein. In addition, ablation of the binding protein compromised growth on glucose and alpha-linked oligosaccharides while inactivation of a previously described glucose transporter had no apparent impact. These data demonstrate that S. solfataricus employs a redundant mechanism for soluble cellodextrin catabolism having both substrate uptake and extracytoplasmic hydrolytic components. Sso1354 is a membrane protein and is possibly glycosylated. The glycosylation pattern of proteins and the effect of a glycosyl transferase mutant on protein glycosylation and fitness of the organism were analyzed. The function of a glycosyl transferase Sso3241 was identified to be important for the transfer of hexose in both the O-linked and N-linked glycosylation of proteins. The mutation also resulted in hot-acid sensitivity to the organism. Further understanding of the effect of pH and temperature adaptation on the glycosylation pattern was obtained by analyzing the three proteins Sso0389, Sso2015, Sso1676 and the endoglucanase Sso1354. The results showed that the glycosylation pattern changed based on the growth pH and temperature and hence can be concluded as an adaptive response.