Inducers gratuitous

Fom- title compounds, 5-deoxy KDG Me estw, 5-epi KDG Me ester, 4-0-Me KDG Me ester and 4-deoxy KDG Me ester were prepared either from D-glucono-l,5-lactone or from 1,2 5,6 di-O-isopropylidene-D-mannitol. Biological tests perfcHined rat these molecules have shown that the compounds modified on the C-5 position (5-deoxy KDG Me ester and 5-epi KDG Me ester) are gratuitous inducers of the e>q>ression of pectinase genes in the phytopathogenic bacteria Erwinia Chrysanthemi when the C-4 modified molecules (4-0-Me KDG Me ester and 4-deoxy KDG Me ester) are not inducers. 

Compounds 13 and 20 were obtained in five and seven steps respectively from the intermediate alcohol 6. They, as well as the acetylated derivative 12, were tested in vivo i and proved to be, as their free acids, gratuitous inducers of pectinases in Erwinia chiysanthemi. These results provide evidence that the hydroxyl function in C-5 is not required for the recognition between inducers and the KdgR repressor protein. Tharefore we can now envisage the preparation of affinity columns, by immoWlizing inducers on suppc rts using a spacer arm boimd to the C-5 hydroxyl. Such columns could then be used for the purification of the repressor protein. 

The common characteristic of compounds that elicit adaptation is the ability to serve as a growth substrate for bacteria. Thus it seems to be the response of a specific population of bacteria to a growth substrate that is responsible for the adaptation. To my knowledge, there are no reports of adaptation to compounds that do not serve as growth substrates. Gratuitous inducers are known but they are not degraded more rapidly as a result of adaptation. 

Dumam, D.M., Pahniter, R.D. 1984. Induction of metallothionein-I mRNA in cultured cells by heavy metals and iodoacetate evidence for gratuitous inducers. Mol. Cell. Biol. 4(3) 484—491. 

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