Polyamine N-acetyltransferase in Leishmania amazonensis

Abstract

N-Acetyltransferase, which is suggested to be responsible for the production of N1-acetylspermidine in Leishmania amazonensis and to be involved in the process of inactivation and degradation of excessive polyamines, was partially purified and characterized. Among the substrates tested, sym-norspermidine, sym-norspermine, and 1,3-diaminopropane had the highest reaction rates, but the naturally occurring polyamines spermine and spermidine were also acetylated at considerable rates, whereas putrescine was a poor substrate. The Michaelis constants (Km values) for spermine and spermidine were 0.66 and 3.3 mM, respectively. The Km value for acetylcoenzyme A (acetyl-CoA) was determined to be 34 microM. CoA inhibited the reaction in a competitive manner; the inhibition constant was 5 microM. The enzyme showed an apparent relative molecular mass of 35,000.

Functions and Biosynthesis of O-Acetylated Sialic Acids

“…Extensive work from the author's group (CM) has convincingly demonstrated that these parasites lack an active machinery for the biosynthesis of this unique sialoglycotope as corroborated by the absence of activity of UDP-GlcNAc 2-epimerase which catalyzes the first step of sialic acid synthesis [77,79]. The presence of N-acetyltransferase in L. amazonensis has indicated the presence of enzymes for acetylation [84]. However, any such claim for the presence of O-acetyltransferase requires the identification of the respective genes that, at present, is lacking.…”

A Perspective on the Emergence of Sialic Acids as Potent Determinants AffectingLeishmaniaBiology

“…Recently reported genome sequences of L. major , L. braziliensis, and L. infantum show conserved gene sequences [66]. N -acetyl transferase producing N 1-acetylspermidine in L. amazonensis indicates the presence of enzymes for acetylation [67]. However, any such claim for the presence of O -acetyltransferase requires the identification of the respective genes which at present is lacking.…”

Leishmania major thialysine Nε‐acetyltransferase: Identification of amino acid residues crucial for substrate binding

“…Based on studies with polyamine synthesis null mutants, it was suggested that at least the species Leishmania donovani does not contain a polyamine interconversion pathway [16]. However, N ‐acetylated forms of spermidine and a polyamine N ‐acetyltransferase activity have been previously determined in Leishmania amazonensis [17,18].…”