Role of acetyl CoA: deacetylcephalosporin C acetyltransferase in cephalosporin C biosynthesis by Cephalosporium acremonium.

Abstract

Existence of an acetyltransferase, which catalizes acetylation of deacetylcephalosporin C to cephalosporin C, was demonstrated for the first time in cell-free extracts of Cephalosporium acremonium.The pH optimum of the enzyme appeared to be 7.0 to 7 .5 and the enzyme required essentially Mg2+ as a cofactor for its reaction. The activity of this enzyme was not observed in the cell-free extracts of deacetylcephalosporin C-producing mutants Nos. 20, 29, 36 and 40, but was recovered in a revertant obtained from the mutant No. 40. These results indicate that deacetylcephalosporin C accumulation by these mutants was due to the lack of the acetyltransferase and made it reasonable that the terminal reaction of cephalosporin C biosynthesis in Cephalosporium acremonium proceeded by the catalytic action of acetyltrans ferase.

Purification of Acetyl Coenzyme A: Deacetylacephalosporin CO-Acetyltransferase fromAcremonium chrysogenum

“…The enzyme followed Michaelis-Menten kinetics, and the Kms for acetyl CoA and DCPC were 1.05 mM and 0.29 mM, respectively. The effect of Mg2 + on DCPC-ATF activity reported by Fujisawa et al 2 ) was not observed (data not shown).…”

“…The DCPC-ATF activity was first reported by Fujisawa et al in cell-free extracts from Acremonium chrysogenum. 2 ) Subsequently the enzyme has been partially purified by Scheidegger et al,3) further purification and characterization have been held up by its extreme instability and the enzyme has been left poorly understood. In this communication, we describe our studies on the stabilization and purification of DCPC-ATF.…”

The cefG gene of Cephalosporium acremonium is linked to the cefEF gene and encodes a deacetylcephalosporin C acetyltransferase closely related to homoserine O-acetyltransferase

“…The last step of the cephalosporin biosynthetic pathway involves the conversion of DAC to cephalosporin C by the enzyme acetyl coenzyme A (acetyl-CoA):DAC acetyltransferase (DAC-acetyltransferase) (13,14) (Fig. 1).…”

Biotechnical Genetics of Antibiotic Biosynthesis

“…In the last step of the cephalosporin C biosynthesis in the fungus C. acremonium, an acetyl moiety from acetyl coenzyme A is transferred to the OH group of DAC catalysed by acetyl coenzyme A: DAC acetyltransferase (Fujisawa and Kanzaki 1975;Felix et al 1980) (Sect. II.D.3.iii).…”

“…1). This reaction is catalysed by acetyl coenzyme A: DAC acetyltransferase (Fujisawa and Kanzaki 1975;Felix et al 1980). The corresponding gene ( cefG) of C. acremonium has been cloned and sequenced by two groups independently (Table 5).…”