PMID- 10413516
OWN - NLM
STAT- MEDLINE
DCOM- 19990915
LR  - 20171116
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 38
IP  - 29
DP  - 1999 Jul 20
TI  - Conformational changes of gp120 in epitopes near the CCR5 binding site are
      induced by CD4 and a CD4 miniprotein mimetic.
PG  - 9405-16
AB  - Binding of the T-cell antigen CD4 to human immunodeficiency virus type 1 (HIV-1) 
      envelope glycoprotein gp120 has been reported to induce conformational
      rearrangements in the envelope complex that facilitate recognition of the CCR5
      coreceptor and consequent viral entry into cells. To better understand the
      mechanism of virus docking and cell fusion, we developed a three-component
      gp120-CD4-17b optical biosensor assay to visualize the CD4-induced conformational
      change of gp120 as seen through envelope binding to a neutralizing human
      antibody, 17b, which binds to epitopes overlapping the CCR5 binding site. The 17b
      Fab fragment was immobilized on a dextran sensor surface, and kinetics of gp120
      binding were evaluated by both global and linear transformation analyses. Adding 
      soluble CD4 (sCD4) increased the association rate of full-length JR-FL gp120 by
      25-fold. This change is consistent with greater exposure of the 17b binding
      epitope on gp120 when CD4 is bound and correlates with CD4-induced conformational
      changes in gp120 leading to higher affinity binding to coreceptor. A smaller
      enhancement of 17b binding by sCD4 was observed with a mutant of gp120,
      DeltaJR-FL protein, which lacks V1 and V2 variable loops and N- and C-termini.
      Biosensor results for JR-FL and DeltaJR-FL argue that CD4-induced conformational 
      changes in the equilibrium state of gp120 lead both to movement of V1/V2 loops
      and to conformational rearrangement in the gp120 core structure and that both of 
      these lead to greater exposure of the coreceptor-binding epitope in gp120. A 17b 
      binding enhancement effect on JR-FL also was observed with a 32-amino acid
      charybdotoxin miniprotein construct that contains an epitope predicted to mimic
      the Phe 43/Arg 59 region of CD4 and that competes with CD4 for gp120 binding.
      Results with this construct argue that CD4-mimicking molecules with surrogate
      structural elements for the Phe 43/Arg 59 components of CD4 are sufficient to
      elicit a similar gp120 conformational isomerization as expressed by CD4 itself.
FAU - Zhang, W
AU  - Zhang W
AD  - Department of Medicine, School of Medicine, University of Pennsylvania,
      Philadelphia 19104, USA.
FAU - Canziani, G
AU  - Canziani G
FAU - Plugariu, C
AU  - Plugariu C
FAU - Wyatt, R
AU  - Wyatt R
FAU - Sodroski, J
AU  - Sodroski J
FAU - Sweet, R
AU  - Sweet R
FAU - Kwong, P
AU  - Kwong P
FAU - Hendrickson, W
AU  - Hendrickson W
FAU - Chaiken, I
AU  - Chaiken I
LA  - eng
GR  - 1PO1 GM 56550-01/GM/NIGMS NIH HHS/United States
GR  - AI28691/AI/NIAID NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (CD4 Antigens)
RN  - 0 (Epitopes, T-Lymphocyte)
RN  - 0 (HIV Envelope Protein gp120)
RN  - 0 (Immunoglobulin Fab Fragments)
RN  - 0 (Peptide Fragments)
RN  - 0 (Receptors, CCR5)
RN  - 115422-61-2 (Charybdotoxin)
SB  - IM
SB  - X
MH  - Amino Acid Sequence
MH  - Binding Sites, Antibody/genetics
MH  - Binding, Competitive/genetics
MH  - Biosensing Techniques
MH  - CD4 Antigens/chemistry/metabolism/*pharmacology
MH  - Charybdotoxin/chemical synthesis/chemistry/metabolism
MH  - Epitopes, T-Lymphocyte/chemistry/*metabolism
MH  - HIV Envelope Protein gp120/genetics/immunology/*metabolism
MH  - *HIV-1
MH  - Humans
MH  - Immunoglobulin Fab Fragments/metabolism
MH  - *Molecular Mimicry
MH  - Molecular Sequence Data
MH  - Peptide Fragments/genetics/metabolism
MH  - Protein Binding/genetics
MH  - Protein Conformation
MH  - Receptors, CCR5/*metabolism
MH  - Sequence Deletion
MH  - Solubility
EDAT- 1999/07/22 00:00
MHDA- 1999/07/22 00:01
CRDT- 1999/07/22 00:00
PHST- 1999/07/22 00:00 [pubmed]
PHST- 1999/07/22 00:01 [medline]
PHST- 1999/07/22 00:00 [entrez]
AID - 10.1021/bi990654o [doi]
AID - bi990654o [pii]
PST - ppublish
SO  - Biochemistry. 1999 Jul 20;38(29):9405-16. doi: 10.1021/bi990654o.