Probing the promiscuity of the HIV1 neutralizing 2F5 antibody

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Probing the promiscuity of the HIV-1 neutralizing
2F5 antibody

• Julien, J.P., Bryson, S., Hynes, R.C.,
  Cunningham, A., Dong, A., Kunert, R., Katinger,
  H., Klein, M., Pai, E.F.
• Department of Biochemistry

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Model of the HIV-1 Env Protein

• Most widely studied neutralizing antibodies
  against gp41
• 2F5
• 4E10

Burton et al. (2004)
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Localization of 2F5 epitope on gp41
Adapted from Zwick et al. (2004)

• Location of epitope is between the C-heptad
  repeat and TM domain
• Core linear sequence
• Glu(E)-Leu(L)-Asp(D)-Lys(K)-Trp(W)-Ala(A)

Adapted from Sanders et al. (2002)
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Experimental Design

• Co-crystallization of 2F5 with peptides mimicking
  the Glu(E)-Leu(L)-Asp(D)-Lys(K)-Trp(W)-Ala(A)-Ser(
  S) epitope
• Structures of 2F5 and peptides with mutations at
  the Asp (D), Lys (K), Trp (W) positions
• Structures of 2F5 and peptides in a different
  crystal form

Zwick et al. (2001)
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Structure of 2F5 and ELDKWAS core epitope
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Structure of 2F5 and peptides with D664E mutation
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Structure of 2F5 and peptides with K665R, K665H
mutations
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Structure of 2F5 and peptides with W666F, W666Y,
W666H mutations
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Conclusions 1

• Importance of negative charge at the Asp(D)
  position (ELDKWA)
• Importance of positive charge at the Lys(K)
  position (ELDKWA)
• Importance of ring at the Trp(W) position
  (ELDKWA)
• Significant in attempt to design molecules
  mimicking 2F5 epitope

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Structure of 2F5 and core peptide in a different
crystal form
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Knowledge gained about structure of 2F5 from new
crystal form

• the CDR3 loop and the C-terminus of the epitope

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Knowledge gained about structure of 2F5 from new
crystal form

• the CDR3 loop and the C-terminus of the epitope

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Structure of 2F5 and elongated peptide LELDKWASLW
N-capped
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Structure of 2F5 and elongated peptide LELDKWASLW
N-capped
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Conclusions 2

• Residues at C-terminus of the DKW core do not
  have specific conformation when complexed with
  2F5 antibody
• 2F5 binding to its epitope does not lock the CDR3
  extended loop in a specific conformation
• CDR3 extended loop might be more flexible than
  previously thought which could allow it to
  interact with a dynamic membrane

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Acknowledgments

• University of Toronto
• Pai Lab
• Dr. Steve Bryson
• Dr. Rosi Hynes
• Annie Cunningham
• Aiping Dong
• Daisy Li
• Dr. Emil F. Pai
• Dr. David Isenman

• Collaborators
• Dr. Hermann Katinger
• Dr. Renate Kunert
• Dr. Michel Klein