Glycosylated triterpenoid saponin: A specific inhibitor of diguanylate cyclase from Acetobacter xylinum. Biological activity and distribution

Patricia Ohana*, Deborah P. Delmer, Gail Volman, Moshe Benziman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

In a recent paper (Ohana et al. 1998), we described the purification and structural characterization of a novel glycosidic triterpenoid saponin (GTS), a specific inhibitor of diguanylate cyclase (dgc), the key regulatory enzyme of the cellulose synthesizing apparatus of the bacterium Acetobacter xylinum. This compound and an identical or very similar one were isolated from pea (Pisum sativum), and A. xylinum respectively. We now present the effects of GTS on the kinetic properties of dgc. The observed inhibition is non-competitive with respect to the substrate GTP, is decreased by 50% in the presence of 20 μM c-di-GMP, and is not observed in the presence of various detergents. Photo-affinity labeling studies using [32P]c-di-GMP and purified enzyme showed that the inhibitor affects binding of c-diGMP to dgc. It was ascertained that GTS, or at least a very similar compound, is present in other plant systems. The antibiotic Papulacandin B also inhibits dgc, although less efficiently than GTS (Ki = 70 μM vs. 5 μM). In in situ assays, highly purified GTS inhibits bacterial cellulose synthesis and dgc activity. Similarly, digitonin permeabilized tobacco cell cultures display inhibition of glucan synthesis in the presence of GTS.

Original languageEnglish
Pages (from-to)153-159
Number of pages7
JournalPlant and Cell Physiology
Volume39
Issue number2
DOIs
StatePublished - Feb 1998
Externally publishedYes

Keywords

  • Acetobacter xylinum
  • c-di-GMP
  • dgc
  • GTS
  • Pisum sativum

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