Agrocinopine C, a Ti-plasmid-coded enzyme-product, is a 2-O, 6-O linked phosphodiester of D-Glucose and sucrose

Abstract

Agrocinopine C is a small molecule found in crown gall tumours induced by pathogenic Agrobacterium radiobacter carrying the tumour-inducing plasmid pTi Bo542. This phosphodiester opine was isolated (at 0.02 g/100 g fresh wt.) from sunflower (Helianthus annuus L.) galls. It is structurally related to agrocinopine A and is a glucose-2-phosphodiester linked to the C6-hydroxy-methyl group of the glucose moiety of sucrose. Sugar-2-phosphates are uncommon in plant tissues, whether transformed by Agrobacterium or not. ¹H and ³¹P NMR signal multiplicity indicates five-fold anomeric complexity of agrocinopine C in solution, implying that the permeases taking up these sucrose-phosphodiesters could recognise any one of the five anomers. Data suggests that the open chain aldehyde forms of the 2-phosphorylated opines agrocinopine C and agrocinopine A and the corresponding phosphorylated glucose-2-phosphoramidate component of the antibiotic agrocin 84 play a central role in agrocin's selective toxicity to certain strains of Agrobacterium after uptake via Ti plasmid-encoded permeases.

Keywords: Acyclic aldehyde-anomers; Agrocinopine; Crown gall; Permease induction; Plant biochemistry; Sucrose phospho-diester; Sugar transport; Ti plasmid.