Journal article
Genetic, biochemical, and crystallographic characterization of Fhit-substrate complexes as the active signaling form of Fhit
Proceedings of the National Academy of Sciences of the United States of America, Vol.95(10), pp.5484-5489
1998
DOI: 10.1073/pnas.95.10.5484
PMID: 9576908
Abstract
Alterations in the FHIT gene at 3p14.2 occur as early and frequent events in the development of several common human cancers. The ability of human Fhit-negative cells to form tumors in nude mice is suppressed by stable reexpression of Fhit protein. Fhit protein is a diadenosine P1,P3-triphosphate (ApppA) hydrolase whose fungal and animal homologs form a branch of the histidine triad (HIT) superfamily of nucleotide-binding proteins. Because the His-96 --> Asn substitution of Fhit, which retards ApppA hydrolase activity by seven orders of magnitude, did not block tumor-suppressor activity in vivo, we determined whether this mutation affected ApppA binding or particular steps in the ApppA catalytic cycle. Evidence is presented that His-96 --> Asn protein binds ApppA well and forms an enzyme-AMP intermediate extremely poorly, suggesting that Fhit-substrate complexes are the likely signaling form of the enzyme. The cocrystal structure of Fhit bound to Ado-p-CH2-p-ps-Ado (IB2), a nonhydrolyzable ApppA analog, was refined to 3.1 A, and the structure of His-96 --> Asn Fhit with IB2 was refined to 2.6 A, revealing that two ApppA molecules bind per Fhit dimer; identifying two additional adenosine-binding sites on the dimer surface; and illustrating that His-98 is positioned to donate a hydrogen bond to the scissile bridging oxygen of ApppA substrates. The form of Fhit bound to two ApppA substrates would present to the cell a dramatically phosphorylated surface, prominently displaying six phosphate groups and two adenosine moieties in place of a deep cavity lined with histidines, arginines, and glutamines.
Details
- Title: Subtitle
- Genetic, biochemical, and crystallographic characterization of Fhit-substrate complexes as the active signaling form of Fhit
- Creators
- Helen C PaceAlexandra DraganescuZurab SiprashviliCarlo M CroceKay HuebnerCharles BrennerPreston N GarrisonAngela K RobinsonLarry D BarnesAngelika RöslerG. Michael Blackburn
- Resource Type
- Journal article
- Publication Details
- Proceedings of the National Academy of Sciences of the United States of America, Vol.95(10), pp.5484-5489
- DOI
- 10.1073/pnas.95.10.5484
- PMID
- 9576908
- NLM abbreviation
- Proc Natl Acad Sci U S A
- ISSN
- 0027-8424
- eISSN
- 1091-6490
- Language
- English
- Date published
- 1998
- Academic Unit
- Biochemistry and Molecular Biology; Internal Medicine
- Record Identifier
- 9983788432202771
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