Acetate kinase

Related Reading

Acetate kinase is a key enzyme in the process of acetic acid production, and it controls the final production of acetic acid. Organic acids such as acetic acid and lactic acid are used as the only carbon source for their metabolism to grow. The first thing in the metabolism of acetic acid is the activation of acetic acid, which needs to be catalyzed by the acetate kinase AK and the phosphotransacetylase PTA: catalyzed by the acetate kinase AK with the participation of ATP, the acetic acid is phosphorylated into acetyl phosphate: then acetyl phosphate is then catalyzed Acetyl-CoA is produced under the catalysis of phosphotransacetylase PTA and enters the tricarboxylic acid cycle for acetate metabolism.

Figure 1. Protein structure of acetate kinase.

Introductions

Acetate kinase is a member of the ASKHA (Acetate and Sugar Kinases, Hsp70, Actin) phosphotransferase superfamily. It is widely present in various organisms and is responsible for catalyzing the reversible reaction of acetyl phosphate and ADP to acetic acid and ATP. The body's carbon source metabolism and energy metabolism play an important role. Especially for lower prokaryotes living in anaerobic or microaerobic environment (such as ruminant rumen, deep rock), this enzyme and Phosphotransacetylase together constitute the key to the process of acetic acid production by organisms At the same time, the enzyme can also regulate other biological reactions in the body through the intermediate acetyl phosphate, which plays a pivotal role in the organism.

Research and significance

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.

Reference

1. Grundy FJ.; et al. Regulation of the Bacillus subtilis acetate kinase gene by CcpA. J. Bacteriol. 1993, 175 (22): 7348–55.