Disease relevance of ackA

• The Bacillus subtilis gene encoding acetate kinase was identified on the basis of sequence similarity to the Escherichia coli ackA gene and to a second E. coli gene closely related to ackA [1].
• Our laboratory previously studied the interaction between nuo and the acetate-producing pathway encoded by ackA-pta in Escherichia coli [2].
• Recent work in this laboratory has shown that the gene coding for acetate kinase (ackA) in Sinorhizobium meliloti is up-regulated in response to phosphate limitation [3].

High impact information on ackA

• Indeed, the ability to synthesize acetyl phosphate, an intermediate of the pathway, appears to be indispensable for glucose-starved cells as pta and pta-ackA double mutants were found to be impaired in their ability to survive glucose starvation [4].
• We propose that cells regulate intracellular acetyl phosphate concentrations relative to growth phase and temperature by modulating the availability of acetyl-CoA, the expression of ackA, and the activity of phosphotransacetylase [5].
• We isolated insertions in ackA and pta, which comprise a two-gene operon responsible for the acetate<-->acetyl coenzyme A interconversion [6].
• An ackA mutant, lacking the ability to generate ATP from acetyl phosphate, also failed to grow in xylose minimal medium under anaerobic conditions, confirming the need for the ATP produced by acetate kinase for anaerobic growth on xylose [7].
• Since arabinose transport by AraE, the low-affinity, high-capacity, arabinose/H+ symport, conserves the ATP expended in pentose transport by the ABC transporter, both pfl and ackA mutants grew anaerobically with arabinose [7].

Biological context of ackA

• Nucleotide sequence analysis and enzyme assays revealed that the DNA fragment contained the ackA gene, which codes for acetate kinase [8].
• The pta gene was found to be downstream of ackA by a combination of restriction analysis and plasmid subcloning [9].
• Conditional ackA silencing reduced carbon flux to acetate and increased heterologous gene expression [10].
• PTasRNAs targeted against the ackA gene within the acetate kinase-phosphotransacetylase operon (ackA-pta) triggered target mRNA decay and a 78% reduction in AckA activity with high genetic penetrance [10].
• Mutations in either ackA alone or both pta and ackA did not affect the nodulation or nitrogen fixation phenotype of S. meliloti [3].

Associations of ackA with chemical compounds

• A similar benefit was obtained by inactivation of acetate kinase (ackA), reducing the production of acetate (and ATP) and sparing acetyl-CoA for biosynthetic needs [11].
• The ackA-pta mutant has a pfl::lacZ expression level much higher than that of the wild-type strain, and cultures also exhibit the highest ethanol production [2].
• The cell yield and lactate productivity were increased by a further mutation in the acetate kinase gene (ackA) [12].
• Earlier we have shown that acetate pathway deletion (ackA-pta) increases isoamyl acetate production [13].

References