Translational regulation of acetogenesis in Acetobacterium woodii

Acetogens synthesize acetyl-CoA via CO2 fixation, producing organic compounds. Despite ecological and industrial importance, their transcriptional and translational regulation has not been systematically studied. Here, we report the first systematic analysis of metabolism of model acetogen Acetobacterium woodii at the transcriptional and translational level, under heterotrophic and autotrophic conditions. Interestingly, Wood-Ljungdahl (WL) pathway and energy conservation system showed increased mRNA levels in the presence of CO2 and H2, but decreased translation efficiency. In particular, the members of methyl-branch and carbonyl-branch are produced at the similar translation level, while the enzymes of the carbonyl branch show more increased translation level than methyl-branch under heterotroph condition. Our data suggest that increased translation levels of the carbonyl-branch and glycine cleavage system under heterotrophic growth condition contribute to additional CO2 fixation and redox balancing. Global 5'-UTR analysis suggested that the 5'-UTR structure and SD sequences regulate the translational efficiency under autotrophic condition. Our findings provide potential strategies to optimize the metabolic process of syngas fermenting for better productivity.