Expression, purification and functional characterization of IκB kinase-2 (IKK-2) mutants

Sumathy Mathialagan, Gennadiy I. Poda, Ravi G. Kurumbail, Shaun R. Selness, Troii Hall, Beverly A. Reitz, Robin A. Weinberg, Nandini Kishore, Gabriel Mbalaviele

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4 Scopus citations


NF-κB signaling plays a pivotal role in a variety of pathological conditions. Because of its central role in the overall NF-κB regulation, IKK-2 is a viable target for drug discovery. In order to enable structure-based design of IKK-2 inhibitors, we carried out a rational generation of IKK-2 mutants based on induced-fit docking of a selective IKK-2 inhibitor, PHA-408, into the homology model of IKK-2. One mutant we have characterized is a catalytically inactive form of IKK-2, D145A IKK-2, wherein the catalytic aspartic acid, D145 was replaced with alanine. Unlike the WT enzyme, D145A IKK-2 is devoid of kinase activity despite its ability to bind ATP with high affinity and is not phosphorylated at the T loop. In addition, this mutant binds a diverse collection of inhibitors with comparable binding affinities to WT IKK-2. Another interesting mutant we have characterized is F26A IKK-2 (F26 is an aromatic residue located at the very tip of the Gly-rich loop). Pre-incubation of F26A IKK-2 with PHA-408 revealed the role of F26 in the time-dependent binding of this inhibitor. Thus, functional characterization of these mutants provides the first evidence showing the role of a Gly-rich loop residue of a kinase in binding kinetics. These two mutants along with others that we have identified could be used to validate homology models and probe the interactions of IKK-2 with a variety of inhibitors.

Original languageEnglish
Pages (from-to)254-261
Number of pages8
JournalProtein Expression and Purification
Issue number2
StatePublished - Aug 2010


  • IKK-2
  • NEMO
  • NF-κB
  • PHA-408


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