Orita Izumi, Sakamoto Naoki, Kato Nobuo, Yurimoto Hiroya, Sakai Yasuyoshi
Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, 606-8502 Kyoto, Japan.
Appl Microbiol Biotechnol. 2007 Aug;76(2):439-45. doi: 10.1007/s00253-007-1023-8. Epub 2007 May 23.
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., hps-phi and phi-hps) from a methylotrophic bacterium Mycobacterium gastri MB19. The gene product of hps-phi 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 phi-hps failed to display any enzyme activity. Escherichia coli strains harboring the hps-phi 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.
甲醛固定酶，即6-磷酸-3-己酮糖合酶（HPS）和6-磷酸-3-己酮糖异构酶（PHI），是催化核糖单磷酸（RuMP）途径中连续反应的关键酶。在本研究中，我们从甲基营养型细菌胃分枝杆菌MB19中构建了hps和phi基因的两个融合基因构建体（即hps-phi和phi-hps）。hps-phi的基因产物在室温下同时表现出HPS和PHI活性，并且比单独酶的简单混合物更有效地催化连续反应。phi-hps的基因产物未显示任何酶活性。携带hps-phi基因的大肠杆菌菌株比宿主菌株更有效地消耗甲醛，并且在含甲醛的培养基中表现出更好的生长。我们的结果表明，工程化融合基因有可能用于在各种生物体中建立抗甲醛解毒系统。
