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Bifunctional enzyme fusion of 3-hexulose-6-phosphate synthase and 6-phospho-3-hexuloisomerase


The formaldehyde-fixing enzymes, 3-Hexulose-6-phosphate synthase (HPS) and 6-phospho-3-hexuloisomerase (PHI), are the key enzymes catalyzing sequential reactions in the ribulose monophosphate (RuMP) pathway. In this study, we generated two fused gene constructs of the hps and phi genes (i.e., hpsphi and phihps) from a methylotrophic bacterium Mycobacterium gastri MB19. The gene product of hpsphi exhibited both HPS and PHI activities at room temperature and catalyzed the sequential reactions more efficiently than a simple mixture of the individual enzymes. The gene product of phihps failed to display any enzyme activity. Escherichia coli strains harboring the hpsphi gene consumed formaldehyde more efficiently and exhibited better growth in a formaldehyde-containing medium than the host strain. Our results demonstrate that the engineered fusion gene has the possibility to be used to establish a formaldehyde-resistance detoxification system in various organisms.

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This paper is supported in part by COE for Microbial-Process Development Pioneering Future Production Systems (COE program of the Ministry of Education, Culture, Sports, Science and Technology, Japan).

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Correspondence to Hiroya Yurimoto.

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Orita, I., Sakamoto, N., Kato, N. et al. Bifunctional enzyme fusion of 3-hexulose-6-phosphate synthase and 6-phospho-3-hexuloisomerase. Appl Microbiol Biotechnol 76, 439–445 (2007).

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  • 3-Hexulose-6-phosphate synthase
  • 6-phospho-3-hexuloisomerase
  • Ribulose monophosphate pathway
  • Mycobacterium gastri
  • Fusion enzyme