11] Methylated polysaccharide activators of fatty acid synthase from Mycobacterium phlei

Abstract

This chapter discusses the methylated polysaccharide activators of fatty acid synthase from Mycobacterium phlei. Mycobacterium species contain in the cytosol two highly methylated polysaccharides, both of them are shown to activate the fatty acid synthase complex of Mycobacterium phlei in a manner leading to a reduction in the Km for acetyl-CoA. The most active substance is composed of 10 3-O-methyl-D-mannose units in α(1→ 4) linkage, forming a chain to which is attached at position 6 of one of the 3-O-methyhnannose units a side chain of two D-mannose units in α(1 → 2) linkage. It is called MMP for methylmannose polysaccharide. The other substance is a lipopolysaccharide containing 7 moles of D-glucose, 10 moles of 6-O-methyl-D-glucose and 1 mole of 3-O-methyl-D-glucose. The polymer is linked to D-glyceric acid and is acylated by acetyl, propionyl, isobutyryl, octanoyl, and succinyl groups. Four forms of the lipopolysaccharide can be isolated depending on the net negative charge, which reflects different contents of succinic acid. These are called MGLP-I, II, III, and IV for methylglucose lipopolysaccharide.