S-adenosyl-L-methionine-dependent protein-cysteine S-methyltransferase with broad substrate specificity. Methylates trehalose-6-phosphate synthase (TPS), enhancing its enzymatic activity and promoting trehalose synthesis upon entry of cells into stationary phase. [trehalose-6-phosphate synthase]-L-cysteine + S-adenosyl-L-methionine = [trehalose-6-phosphate synthase]-S-methyl-L-cysteine + H(+) + S-adenosyl-L-homocysteine Optimum pH is 7. Optimum temperature is 30 degrees Celsius. Exhibits almost 50% reduction in intracellular trehalose concentration.