vFLIP-IKKg Blocker

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vFLIP-IKKg Blocker

• Edith Chan
• WIBR

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NF-kB Pathway

• The Nf-kB pathway is related to inflammatory
  responses, cell death, and oncogenesis.
• Kaposis sarcoma herpesvirus (KSHV) encoded FLIP
  (vFLIP) binds to IKKg to activate NFkB.
• Similarly, in human, cFLIP can associated with
  IKKg and thus has a wider application in cancer
  therapies.

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Work Study

• The study focuses on using X-ray crystal
  structures, biophysical screening and structure
  based design to identify blockers of the
  vFLIP-IKKg and p22-cFLIP-IKKg interaction,
  conducting lead optimisation and identifying a
  development candidate.
• My immediate actions are
• Understanding of the interaction of the
  vFLIP-IKKg complex using X-ray crystal structure
• Selection of compounds mimicking the IKKg
  interaction of the complex

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X-ray crystal structure

• Our collaborators at BBK have solved the
  structure between vFLIP-IKKg (3cl3).
• Full length IKKg is 419aa long mulitdomain
  protein
• Both proteins are truncated
• ks-vFLIP (aa1-178) 188aa
• IKKg (aa150-272) 419aa
• The X-ray structure comprised of a dimer of two
  ks-vFLIP-IKKg complex.
• The two vFLIP molecules come together solely
  through interactions between the two IKKg chains.

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Protein-Protein Interactions

• Each of the IKKg helix is interacting with a copy
  of the vFLIP via two adjacent vertical clefts
  (cleft 1 and 2)
• Cleft 1 involved more interactions between the
  complex, the hottest spot seems to be around
  Phe238 (of IKKg)

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Peptide tool compound
vFLIP

• Full length IKKg is 419aa long mulitdomain
  protein. In the X-ray structure, only the HLX2
  (helix) domains (aa193-253) are co-crystallized
  with ks-vFLIP.
• As seen from the picture, only a portion of the
  IKKg is interacting with vFLIP. They are about
  20aa long as highlighted in a pink box.
• Our first step is to use of peptide as proof of
  concept tool in further experiments
• Can a shorter peptide of IKKg be sufficient to
  bind with vFLIP?
• Can a shorter peptide adopt helical conformation
  on its own or by recognition to vFLIP?

C-terminus
N-terminus
IKKg
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Proposed tool Peptides

• 
  Length AA
  spin
• Longer peptide include C-terminus 30aa aa224-253
  
• Spin the entire interaction with
  vFLIP 21aa aa226-246
• Peptide that covers cleft1 interaction 16aa aa231
  -246
• Peptide that covers cleft2 interaction 15aa aa226
  -240
• Peptide that covers all essential interaction
  12aa aa231-242