Control of dinucleoside polyphosphates by the FHIT-homologous HNT2 gene, adenine biosynthesis and heat shock in Saccharomyces cerevisiae

• Main Authors: Rubio-Texeira, Marta (Contributor), Varnum, James M (Author), Bieganowski, Pawel (Author), Brenner, Charles (Author)
• Other Authors: Massachusetts Institute of Technology. Department of Biology (Contributor)
• Format: Article
• Language: English
• Published: BioMed Central Ltd, 2010-10-12T13:08:46Z.
• Subjects: Article
• Online Access: Get fulltext

 Background: The FHIT gene is lost early in the development of many tumors. Fhit possesses intrinsic ApppA hydrolase activity though ApppA cleavage is not required for tumor suppression. Because a mutant form of Fhit that is functional in tumor suppression and defective in catalysis binds ApppA well, it was hypothesized that Fhit-substrate complexes are the active, signaling form of Fhit. Which substrates are most important for Fhit signaling remain unknown. Results: Here we demonstrate that dinucleoside polyphosphate levels increase 500-fold to hundreds of micromolar in strains devoid of the Saccharomyces cerevisiae homolog of Fhit, Hnt2. Accumulation of dinucleoside polyphosphates is reversed by re-expression of Hnt2 and is active site-dependent. Dinucleoside polyphosphate levels depend on an intact adenine biosynthetic pathway and time in liquid culture, and are induced by heat shock to greater than 0.1 millimolar even in Hnt2+ cells. Conclusions: The data indicate that Hnt2 hydrolyzes both ApppN and AppppN in vivo and that, in heat-shocked, adenine prototrophic yeast strains, dinucleoside polyphosphates accumulate to levels in which they may saturate Hnt2.