CobB1 deacetylase activity in Streptomyces coelicolor.

Silent information regulators are NAD(+)-dependent enzymes that display differential specificity toward acetylated substrates. This report provides first evidence for deacetylation activity of CobB1 in Streptomyces coelicolor. The protein is highly conserved in streptomycetes. The CobB1 protein catalytically removes the acetyl group from acetylated bovine serum albumin. In the absence of NAD+ or when NAD+ was substituted with nicotinamide, deacetylation was stopped. We isolated gene encoding AcetylCoA synthetaseA. The recombinant enzyme produces Acetyl-CoA from acetate. The highest acsA-mRNA level was detected in cells from the exponential phase of growth, and then decreased in transition and stationary phases of growth. Acetylated acsA loses the ability to transfer acetate to CoA. Deacetylation of the enzyme required CobB1, ATP-Mg2, and NAD+. Using specific antibodies against acetylated lys, CobB1, and acsA, we found relationship between level of CobB1 and acetylation of acsA, indicating that CobB1 is involved in regulating the acetylation level of acsA and consequently its activity. It was found that 1-acetyl-tetrahydroxy and 1-acetyl pentahydroxy antraquinone inhibit the deacetylation activity of CobB1.