Trehalose protects Escherichia coli against carbon stress manifested by protein acetylation and aggregation.

The disaccharide trehalose is widely distributed in nature and can serve as a carbon reservoir, a signaling molecule for controlling glucose metabolism and a stress protectant. We demonstrated that in Escherichia coli Delta otsA cells, which are unable to synthesize trehalose, the aggregation of endogenous proteins during the stationary phase was increased in comparison to wild-type cells. The lack of trehalose synthesis boosted N epsilon-lysine acetylation of proteins, which in turn enhanced their hydrophobicity and aggregation. This increased N epsilon-lysine acetylation could result from carbon overflow and the accumulation of acetyl phosphate caused by the Delta otsA mutation. These findings provide a better understanding of the previously reported protective functions of trehalose in protein stabilization and the prevention of protein aggregation. Our results indicate that trehalose may participate in proteostasis not only as a chemical chaperone but also as a metabolite that indirectly counteracts detrimental protein acetylation. We propose that trehalose protects E. coli against carbon stress - the synthesis and storage of trehalose can prevent carbon overflow, which otherwise is manifested by protein acetylation and aggregation.