Diphospho-myo-inositol phosphates in Dictyostelium and Polysphondylium:: identification of a new bisdiphospho-myo-inositol tetrakisphosphate

The two major diphospho inositol phosphates from the axenic strain Dictyostelium discoideum AX2 were previously investigated and identified as 6-PP-InsP(5) and 5,6-bis-PP-InsP(4). In order to examine whether these findings are representative of Dictyostelids in general, five non-axenic wild-type species of Dictyostelium and two of Polysphondylium were studied. It was found that all of the Dictyostelium species exhibit similar patterns of diphospho inositol phosphates, By contrast, both of the Polysphondylium species contain 5-PP-InsP(5) as the predominant isomer, Besides 5,6-bis-PP-InsP(4), a new bis-PP-InsP(4) was detected in Polysphondylium. This compound is either 1,5-bis-PP-InsP(4) or its corresponding enantiomer 3,5-bis-PP-InsP(5),. The structures were elucidated by two-dimensional H-1-H-1 and H-1-P-31 NMR analysis. Additionally, they were confirmed using a specific 6-PP-InsP(5)-5-kinase from D, discoideum AX2 as an enantio-specific tool and enantiomerically pure reference standards. (C) 1998 Federation of European Biochemical Societies.