The multiple effects of REG1 deletion and SNF1 overexpression improved the production of S-adenosyl-L-methionine in Saccharomyces cerevisiae.

BACKGROUND: Saccharomyces cerevisiae is often used as a cell factory for the production of S-adenosyl-L-methionine (SAM) for diverse pharmaceutical applications. However, SAM production by S. cerevisiae is negatively influenced by glucose repression, which is regulated by a serine/threonine kinase SNF1 complex. Here, a strategy of alleviating glucose repression by deleting REG1 (encodes the regulatory subunit of protein phosphatase 1) and overexpressing SNF1 (encodes the catalytic subunit of the SNF1 complex) was applied to improve SAM production in S. cerevisiae. SAM production, growth conditions, glucose consumption, ethanol accumulation, lifespan, glycolysis and amino acid metabolism were analyzed in the mutant strains. RESULTS: The results showed that the multiple effects of REG1 deletion and/or SNF1 overexpression exhibited a great potential for improving the SAM production in yeast. Enhanced the expression levels of genes involved in glucose transport and glycolysis, which improved the glucose utilization and then elevated the levels of glycolytic intermediates. The expression levels of ACS1 (encoding acetyl-CoA synthase I) and ALD6 (encoding aldehyde dehydrogenase), and the activity of alcohol dehydrogenase II (ADH2) were enhanced especially in the presence of excessive glucose levels, which probably promoted the conversion of ethanol in fermentation broth into acetyl-CoA. The gene expressions involved in sulfur-containing amino acids were also enhanced for the precursor amino acid biosynthesis. In addition, the lifespan of yeast was extended by REG1 deletion and/or SNF1 overexpression. As expected, the final SAM yield of the mutant YREG1ΔPSNF1 reached 8.28 g/L in a 10-L fermenter, which was 51.6% higher than the yield of the parent strain S. cerevisiae CGMCC 2842. CONCLUSION: This study showed that the multiple effects of REG1 deletion and SNF1 overexpression improved SAM production in S. cerevisiae, providing new insight into the application of the SNF1 complex to abolish glucose repression and redirect carbon flux to nonethanol products in S. cerevisiae.

The efficacy and safety of remimazolam tosylate versus propofol in patients undergoing colonoscopy: a multicentered, randomized, positive-controlled, phase III clinical trial.

This study aimed to evaluate the efficacy and safety of remimazolam tosylate versus propofol in patients undergoing colonoscopy. In this multicentered, blinded, randomized, active-controlled, non-inferior phase III trial, 384 eligible patients who were about to undergo colonoscopy were randomized as a ratio of 1:1 into remimazolam and propofol group. Procedure success was assessed and defined as the completion of colonoscopy without administration of rescue sedative agent or more than 5 top-ups of trial drug in any 15 minute-period after initial administration of trial drug. Sedation quality was evaluated by Modified Observer's Assessment of Alertness/Sedation score. Treatment-emergent adverse events were recorded. Procedure success rate was 96.91% (188/194) in remimazolam group and 100% (190/190) in propofol group, and the difference in rate was -3.09% with 95% confidence interval (CI) of -5.53%~-0.66%. Since the lower limit of 95% CI was greater than the non-inferiority margin of -8.00%, the efficacy of remimazolam tosylate was non-inferior to propofol. Besides, induction time of sedation was increased (P<0.001), while hypotension and respiratory depression was decreased in remimazolam group compared to propofol group; however, time to fully alert (P>0.05) or time to discharge (P>0.05) were unchanged. For safety assessment, total treatment-emergent adverse events were decreased in remimazolam group compared to propofol group (P<0.001); specifically, administration site pain (P<0.001), increased bilirubin (P=0.019), decreased respiratory rate (P<0.001) and decreased SpO2 (P<0.001) were less frequent in remimazolam group compared with propofol group. In conclusion, remimazolam tosylate is non-inferior in sedation efficacy while safer than propofol in patients undergoing colonoscopy.