Studies on molecular mechanisms involved in the nicotinamide-cofactor homeostasis in thermophiles and their application to in vitro metabolic engineering

2016 Fiscal Year Final Research Report

• Project/Area Number: 26450088
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Applied microbiology
• Research Institution: Osaka University
• Principal Investigator: Honda Kohsuke 大阪大学, 工学研究科, 准教授 (90403162)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: ニコチンアミド補酵素 / NAD(H) / 好熱菌 / Thermus thermophilus / サルベージ合成

Outline of Final Research Achievements

Nicotinamide cofactors are involved in a wide variety of enzymatic redox reactions and ubiquitously present in all organisms. Although thermophiles also use these cofactors, nicotinamide cofactors are readily degraded at high temperatures where thermophiles preferably grow. To address this discrepancy, we have characterized enzymes composing the salvage synthesis of NAD+ in a thermophilic bacterium, Thermus thermophilus, and evaluated their importance in the bacterial growth at high temperatures. As a result, we newly identified the gene encoding nicotinamidase, which is engaged in the first step of the salvage synthesis of NAD+, of T. thermophilus. Disruption of this gene resulted in a marked decrease in the bacterial growth at 80°C. In addition, we reconstituted the NAD+ salvage pathway in vitro using thermophilic enzymes. In the presence of reconstituted pathway, NAD+ concentration could be kept almost constant at 60°C for 15 h.

Free Research Field

酵素工学