アセテートキナーゼ

関連する読書

アセテートキナーゼは酢酸生成プロセスにおける重要な酵素であり、酢酸の最終生成を制御します。酢酸や乳酸などの有機酸は、成長のための代謝の唯一の炭素源として使用されます。酢酸の代謝において最初に行われるのは酢酸の活性化であり、これはアセテートキナーゼAKとホスホトランスアセチラーゼPTAによって触媒される必要があります。アセテートキナーゼAKがATPの参加を伴って触媒することで、酢酸はアセチルリン酸にリン酸化されます。次に、アセチルリン酸はホスホトランスアセチラーゼPTAの触媒の下でアセチルCoAに変換され、酢酸の代謝のために三カルボン酸回路に入ります。

図1. アセテートキナーゼのタンパク質構造。

はじめに

アセテートキナーゼはASKHA（アセテートおよび糖キナーゼ、Hsp70、アクチン）ホスホトランスファラーゼスーパーファミリーの一員です。さまざまな生物に広く存在し、アセチルリン酸とADPを酢酸とATPに可逆的に反応させる触媒の役割を担っています。体内の炭素源の代謝とエネルギー代謝は重要な役割を果たします。特に嫌気性または微好気性環境（反芻動物のルーメン、深い岩など）に生息する下等原核生物にとって、この酵素とホスホトランスアセチラーゼは、酢酸生成プロセスの鍵を構成します。同時に、この酵素は中間体アセチルリン酸を介して体内の他の生物反応を調節することもでき、生物において重要な役割を果たします。

研究と意義

参考文献

1. Grundy FJ.; et al. CcpAによるバチルス・サブチリスのアセテートキナーゼ遺伝子の調節. J. Bacteriol. 1993, 175 (22): 7348–55.

1. Acetic acid is one of the end products of energy metabolism of most facultative and strictly anaerobic microorganisms. Conversely, acetic acid also has the effect of regulating central metabolism and hydrogen production metabolism. During the operation of the biological hydrogen production reactor, the secretion of a large amount of acetic acid will cause the pH change in the reactor, and the pH change can change the type of fermentation of the microorganisms in the reactor, affect the stability of the reaction, and consequently inhibit the growth of bacteria. Growth reduces H₂ production; and the method of adjusting pH with alkali will increase production costs.
2. In the process of acetic acid production, acetate kinase is the key enzyme, which controls the final production of acetic acid. Therefore, clone the acetate kinase gene and study its physiological and biochemical effects in the metabolic pathway of hydrogen production, so as to provide a basis for optimizing the optimal hydrogen production metabolic process.
3. The enzyme activity regulation of PTA and AK in acetic acid metabolism is similar. Studies have also found that when wild Corynebacterium glutamicum grows on a medium that uses acetic acid (instead of glucose) as a carbon source, the enzyme activities of PTA and AK are significantly increased. This phenomenon is a concrete manifestation of the glucose effect in microbial carbon metabolism, which implies that these enzymes may have negative regulatory effects on the glucose substrate or positive regulatory effects on the acetic acid substrate in the link of gene expression.
4. In addition, when the amrGl gene is deleted or overexpressed, the regulation of PTA and AK enzyme activity has a certain change rule. According to the experimental results, the PTA and AK enzyme activities of the gene-deficient strains were significantly increased when they were grown on the glucose carbon source, and the basic medium containing the two carbon sources of glucose and acetic acid showed a single carbon source medium with acetate. The same enzyme activity. On the contrary, the overexpression strain of amrGl gene has a certain degree of reduction of PTA and AK enzyme activity on glucose medium.