2FHI

SUBSTRATE ANALOG (IB2) COMPLEX WITH THE HIS 96 ASN SUBSTITUTION OF THE FRAGILE HISTIDINE TRIAD PROTEIN, FHIT

Summary for 2FHI

• Entry DOI: 10.2210/pdb2fhi/pdb
• Descriptor: FRAGILE HISTIDINE TRIAD PROTEIN, P1-P2-METHYLENE-P3-THIO-DIADENOSINE TRIPHOSPHATE (3 entities in total)
• Functional Keywords: nucleotide-binding protein, cancer, diadenosine triphosphate hydrolase, active site substitution, histidine triad, tumor suppressor
• Biological source: Homo sapiens (human)
• Cellular location: Cytoplasm: P49789
• Total number of polymer chains: 1
• Total formula weight: 17632.66

Authors

Pace, H.C.,Garrison, P.N.,Robinson, A.K.,Barnes, L.D.,Draganescu, A.,Rosler, A.,Blackburn, G.M.,Siprashvili, Z.,Croce, C.M.,Heubner, K.,Brenner, C. (deposition date: 1998-04-01, release date: 1998-06-17, Last modification date: 2024-05-29)

Primary citation

Pace, H.C.,Garrison, P.N.,Robinson, A.K.,Barnes, L.D.,Draganescu, A.,Rosler, A.,Blackburn, G.M.,Siprashvili, Z.,Croce, C.M.,Huebner, K.,Brenner, C.
Genetic, biochemical, and crystallographic characterization of Fhit-substrate complexes as the active signaling form of Fhit.
Proc.Natl.Acad.Sci.USA, 95:5484-5489, 1998

PubMed 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.

PubMed: 9576908
DOI: 10.1073/pnas.95.10.5484

Experimental method

X-RAY DIFFRACTION (2.6 Å)