title: Oligomeric interface modulation causes misregulation of purine 5´-nucleotidase in relapsed leukemia.
abstract: Relapsed acute lymphoblastic leukemia (ALL) is one of the main causes of mortality in childhood malignancies. Previous genetic studies demonstrated that chemoresistant ALL is driven by activating mutations in NT5C2, the gene encoding cytosolic 5´-nucleotidase (cN-II). However, molecular mechanisms underlying this hyperactivation are still unknown. Here, we present kinetic and structural properties of cN-II variants that represent 75 % of mutated alleles in patients who experience relapsed ALL (R367Q, R238W and L375F).
  
  
  
  Enzyme kinetics measurements revealed that the mutants are consitutively active without need for allosteric activators. This shows that hyperactivity is not caused by a direct catalytic effect but rather by misregulation of cN-II. X-ray crystallography combined with mass spectrometry-based techniques demonstrated that this misregulation is driven by structural modulation of the oligomeric interface within the cN-II homotetrameric assembly. These specific conformational changes are shared between the studied variants, despite the relatively random spatial distribution of the mutations.
  
  
  
  These findings define a common molecular mechanism for cN-II hyperactivity, which provides a solid basis for targeted therapy of leukemia. Our study highlights the cN-II oligomerization interface as an attractive pharmacological target.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, Prague 6, 166 10, Czech Republic. hnizda@uochb.cas.cz.
authors.forename: Aleš
authors.initials: A
authors.lastname: Hnízda
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, Prague 6, 166 10, Czech Republic.
authors.forename: Jana
authors.initials: J
authors.lastname: Škerlová
authors.affiliation: Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083, Prague 4, 142 20, Czech Republic.
authors.forename: Milan
authors.initials: M
authors.lastname: Fábry
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, Prague 6, 166 10, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Pachl
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, Prague 6, 166 10, Czech Republic.
authors.forename: Martina
authors.initials: M
authors.lastname: Šinalová
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, Prague 6, 166 10, Czech Republic.
authors.forename: Lukáš
authors.initials: L
authors.lastname: Vrzal
authors.affiliation: Institute of Microbiology, Academy of Sciences of the Czech Republic, Videnska 1083, Prague 4, 142 20, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Man
authors.affiliation: Institute of Microbiology, Academy of Sciences of the Czech Republic, Videnska 1083, Prague 4, 142 20, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Novák
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, Prague 6, 166 10, Czech Republic.|Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083, Prague 4, 142 20, Czech Republic.
authors.forename: Pavlína
authors.initials: P
authors.lastname: Řezáčová
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, Prague 6, 166 10, Czech Republic. veverka@uochb.cas.cz.
authors.forename: Václav
authors.initials: V
authors.lastname: Veverka
mesh_terms: D015720:5'-Nucleotidase / Q000235:genetics* / Q000378:metabolism; D000483:Alleles; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D009154:Mutation; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000201:enzymology / Q000235:genetics*; D011487:Protein Conformation; D012008:Recurrence
chemical_list: D015720:5'-Nucleotidase; C508048:NT5C2 protein, human
keywords: Allosteric regulation; Cancer mutations; Nucleotidase; Purine metabolism; Relapsed ALL