Chemical modification of recombinant HIV-1 capsid protein p24 leads to the release of a hidden epitope prior to changes of the overall folding of the protein.


Abstract

It was found that the affinity of a monoclonal antibody directed against a recombinantly expressed HIV-1 capsid protein p24 (rp24) strongly increased after chemical modification of the Iysine residues of rp24 with different amounts of maleic anhydride. The extent and the sites of modification were analyzed by MALDI-TOF mass spectrometry. Unmodified rp24 and the differently modified rp24 samples were tested for binding the murine monoclonal antibody CB4-1 which recognizes the epitope GATPQDLNTML comprising residues 46-56 of rp24. An increase in the number of modified lysine residues led to enhanced binding affinity of CB4-1. Most pronounced effects were observed after substitution of the first amino groups: an average number of three modified residues per protein molecule increases the binding affinity by a factor of 23, but the substitution of the remaining nine residues increases the binding affinity only by a factor of 11. Fully modified rp24 variant proteins were bound by CB4-1 with Kd values comparable to that of the peptide epitope. Conformation and stability of the unmodified rp24, highly (rp24F, 9 residues; rp24G, 11 residues) modified, and fully modified protein (rp24I, 11 lysine residues and N-terminus) were analyzed by circular dichroism (CD) and fluorescence spectroscopy under different solvent conditions. Little difference in conformation and unfolding behavior was observed between the unmodified and highly modified rp24, which differ drastically in the antibody binding behavior. The fully modified sample, however, displayed a significant decrease in alpha-helical content. Thus, the epitope seems to be hidden (cryptotope) in the unmodified rp24 in a low-affinity binding conformation and becomes displayed at low levels of chemical modification which obviously induce subtle structural changes prior to changes of the overall folding observable by spectroscopic means. Study holds ProTherm entries: 4674 Extra Details: chemical modification; binding affinity; modified protein;,structural changes

Submission Details

ID: oka8e9r84

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:26 p.m.

Version: 1

Publication Details
Ehrhard B;Misselwitz R;Welfle K;Hausdorf G;Glaser RW;Schneider-Mergener J;Welfle H,Biochemistry (1996) Chemical modification of recombinant HIV-1 capsid protein p24 leads to the release of a hidden epitope prior to changes of the overall folding of the protein. PMID:8703914
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P
 

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)


Relevant PDB Entries

Structure ID Release Date Resolution Structure Title
1AAF 1992-04-06T00:00:00+0000 0 NUCLEOCAPSID ZINC FINGERS DETECTED IN RETROVIRUSES: EXAFS STUDIES ON INTACT VIRUSES AND THE SOLUTION-STATE STRUCTURE OF THE NUCLEOCAPSID PROTEIN FROM HIV-1
1FGL 1996-11-18T00:00:00+0000 1.8 Cyclophilin A complexed with a fragment of HIV-1 GAG protein
2FXE 2006-02-05T00:00:00+0000 1.8 X-ray crystal structure of HIV-1 protease CRM mutant complexed with atazanavir (BMS-232632)
2R05 2007-08-17T00:00:00+0000 2.55 Crystal Structure of ALIX/AIP1 in complex with the HIV-1 YPLASL Late Domain
1HHJ 1993-06-30T00:00:00+0000 2.5 THE ANTIGENIC IDENTITY OF PEPTIDE(SLASH)MHC COMPLEXES: A COMPARISON OF THE CONFORMATION OF FIVE PEPTIDES PRESENTED BY HLA-A2
3IXO 2009-09-04T00:00:00+0000 1.7 Crystal Structure of uncomplexed HIV_1 Protease Subtype A
1HVN 1992-12-08T00:00:00+0000 0 ZINC-AND SEQUENCE-DEPENDENT BINDING TO NUCLEIC ACIDS BY THE N-TERMINAL ZINC FINGER DOMAIN OF THE HIV-1 NUCLEOCAPSID PROTEIN: NMR STRUCTURE OF THE COMPLEX WITH THE PSI-SITE ANALOG, D/ACGCC
1HVO 1992-12-08T00:00:00+0000 0 ZINC-AND SEQUENCE-DEPENDENT BINDING TO NUCLEIC ACIDS BY THE N-TERMINAL ZINC FINGER DOMAIN OF THE HIV-1 NUCLEOCAPSID PROTEIN: NMR STRUCTURE OF THE COMPLEX WITH THE PSI-SITE ANALOG, D/ACGCC
1KJ4 2001-12-04T00:00:00+0000 2.9 SUBSTRATE SHAPE DETERMINES SPECIFICITY OF RECOGNITION RECOGNITION FOR HIV-1 PROTEASE: ANALYSIS OF CRYSTAL STRUCTURES OF SIX SUBSTRATE COMPLEXES
1KJ7 2001-12-04T00:00:00+0000 2.0 SUBSTRATE SHAPE DETERMINES SPECIFICITY OF RECOGNITION RECOGNITION FOR HIV-1 PROTEASE: ANALYSIS OF CRYSTAL STRUCTURES OF SIX SUBSTRATE COMPLEXES

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
90.7 Gag-Pol polyprotein Q1A249 POL_SIVEK
90.7 Gag-Pol polyprotein Q1A250 GAG_SIVEK
91.9 Gag-Pol polyprotein Q77373 POL_HV1AN
91.9 Gag-Pol polyprotein Q77372 GAG_HV1AN
91.9 Gag-Pol polyprotein Q9WC63 POL_HV1S9
91.9 Gag-Pol polyprotein Q9WC54 POL_HV1S2
91.9 Gag-Pol polyprotein Q9QBZ9 POL_HV197
91.9 Gag-Pol polyprotein O89290 POL_HV193
91.9 Gag-Pol polyprotein Q9WC62 GAG_HV1S9
91.9 Gag-Pol polyprotein Q9WC53 GAG_HV1S2
91.9 Gag-Pol polyprotein Q9QC00 GAG_HV197
91.9 Gag-Pol polyprotein O89291 GAG_HV193
91.9 Gag-Pol polyprotein Q9IDV9 POL_HV1YB
95.3 Gag-Pol polyprotein P05961 POL_HV1MN
91.9 Gag-Pol polyprotein O41798 POL_HV19N
91.9 Gag-Pol polyprotein Q9IDV8 GAG_HV1YB
91.9 Gag-Pol polyprotein P0C1K7 GAG_HV19N
91.9 Gag-Pol polyprotein O91080 POL_HV1YF
91.9 Gag-Pol polyprotein O91079 GAG_HV1YF
91.9 Gag-Pol polyprotein Q9QBZ1 POL_HV1M2
90.7 Gag-Pol polyprotein O12158 POL_HV192
91.9 Gag-Pol polyprotein Q9QBZ2 GAG_HV1M2
90.7 Gag-Pol polyprotein O12157 GAG_HV192
93.0 Gag-Pol polyprotein P05959 POL_HV1RH
91.9 Gag-Pol polyprotein Q9QBY3 POL_HV196
93.0 Gag-Pol polyprotein P05890 GAG_HV1RH
91.9 Gag-Pol polyprotein Q9QBY4 GAG_HV196
95.3 Gag-Pol polyprotein P12499 POL_HV1Z2
95.3 Gag-Pol polyprotein P12495 GAG_HV1Z2
95.3 Gag-Pol polyprotein P17283 POL_SIVCZ
95.3 Gag-Pol polyprotein P17282 GAG_SIVCZ
93.0 Gag-Pol polyprotein P24740 POL_HV1U4
95.3 Gag-Pol polyprotein P04589 POL_HV1EL
93.0 Gag-Pol polyprotein P24736 GAG_HV1U4
95.3 Gag-Pol polyprotein P04592 GAG_HV1EL
93.0 Gag-Pol polyprotein Q9QBZ5 POL_HV1MP
93.0 Gag-Pol polyprotein Q9QBZ6 GAG_HV1MP
95.3 Gag-Pol polyprotein P04588 POL_HV1MA
95.3 Gag-Pol polyprotein P04594 GAG_HV1MA
96.5 Gag-Pol polyprotein P18802 POL_HV1ND
96.5 Gag-Pol polyprotein P18800 GAG_HV1ND
96.5 Gag-Pol polyprotein P20875 POL_HV1JR
96.5 Gag-Pol polyprotein P20873 GAG_HV1JR
97.7 Gag-Pol polyprotein P05960 POL_HV1C4
97.7 Gag-Pol polyprotein P05887 GAG_HV1C4
97.7 Gag-Pol polyprotein P12498 POL_HV1J3
97.7 Gag-Pol polyprotein P05888 GAG_HV1MN
97.7 Gag-Pol polyprotein P12494 GAG_HV1J3
97.7 Gag-Pol polyprotein P20892 POL_HV1OY
97.7 Gag-Pol polyprotein P03369 POL_HV1A2
97.7 Gag-Pol polyprotein P05889 GAG_HV1W2
97.7 Gag-Pol polyprotein P20889 GAG_HV1OY
97.7 Gag-Pol polyprotein P03349 GAG_HV1A2
97.7 Gag-Pol polyprotein Q73368 POL_HV1B9
97.7 Gag-Pol polyprotein Q73367 GAG_HV1B9
98.8 Gag-Pol polyprotein P35963 POL_HV1Y2
98.8 Gag-Pol polyprotein P0C6F2 POL_HV1LW
98.8 Gag-Pol polyprotein P04585 POL_HV1H2
98.8 Gag-Pol polyprotein P03367 POL_HV1BR
98.8 Gag-Pol polyprotein P04587 POL_HV1B5
98.8 Gag-Pol polyprotein P03366 POL_HV1B1
98.8 Gag-Pol polyprotein P35962 GAG_HV1Y2
98.8 Gag-Pol polyprotein Q70622 GAG_HV1LW
98.8 Gag-Pol polyprotein P04591 GAG_HV1H2
98.8 Gag-Pol polyprotein P03348 GAG_HV1BR
98.8 Gag-Pol polyprotein P04593 GAG_HV1B5
98.8 Gag-Pol polyprotein P03347 GAG_HV1B1
100.0 Gag-Pol polyprotein P12497 POL_HV1N5
100.0 Gag-Pol polyprotein P12493 GAG_HV1N5