PDBsum entry 3gi4

Hydrolase/hydrolase inhibitor

PDB id: 3gi4

Contents

Protein chains

99 a.a. *

Ligands

K60

PO4 ×2

ACT ×2

Waters ×140

* Residue conservation analysis

PDB id:

3gi4

Name:

Hydrolase/hydrolase inhibitor

Title:

Crystal structure of protease inhibitor, kb60 in complex with wild type HIV-1 protease

Structure:

Protease. Chain: a, b. Engineered: yes

Source:

Human immunodeficiency virus 1. Organism_taxid: 11676. Strain: sf2. Gene: pol. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.85Å R-factor: 0.172 R-free: 0.221

Authors:

M.N.L.Nalam,C.A.Schiffer

Key ref:

M.N.Nalam et al. (2010). Evaluating the substrate-envelope hypothesis: structural analysis of novel HIV-1 protease inhibitors designed to be robust against drug resistance. J Virol, 84, 5368-5378. PubMed id: 20237088

Date:

05-Mar-09 Release date: 09-Mar-10

Protein chains

P03369  (POL_HV1A2) -  Gag-Pol polyprotein from Human immunodeficiency virus type 1 group M subtype B (isolate ARV2/SF2)

Seq: 1437 a.a.

Struc: 99 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Enzyme reactions

• Enzyme class 1: E.C.2.7.7.- - ?????
• Enzyme class 2: E.C.2.7.7.49 - RNA-directed Dna polymerase.
• Reaction: DNA(n) + a 2'-deoxyribonucleoside 5'-triphosphate = DNA(n+1) + diphosphate

DNA(n) + 2'-deoxyribonucleoside 5'-triphosphate = DNA(n+1) (Bound ligand (Het Group name = PO4) matches with 55.56% similarity) + diphosphate

• Enzyme class 3: E.C.2.7.7.7 - DNA-directed Dna polymerase.
• Reaction: DNA(n) + a 2'-deoxyribonucleoside 5'-triphosphate = DNA(n+1) + diphosphate

DNA(n) + 2'-deoxyribonucleoside 5'-triphosphate = DNA(n+1) (Bound ligand (Het Group name = PO4) matches with 55.56% similarity) + diphosphate

• Enzyme class 4: E.C.3.1.-.-
• Enzyme class 5: E.C.3.1.13.2 - exoribonuclease H.
• Reaction: Exonucleolytic cleavage to 5'-phosphomonoester oligonucleotides in both 5'- to 3'- and 3'- to 5'-directions.
• Enzyme class 6: E.C.3.1.26.13 - retroviral ribonuclease H.
• Enzyme class 7: E.C.3.4.23.16 - HIV-1 retropepsin.
• Reaction: Specific for a P1 residue that is hydrophobic, and P1' variable, but often Pro.

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

J Virol 84:5368-5378 (2010)

PubMed id: 20237088

Evaluating the substrate-envelope hypothesis: structural analysis of novel HIV-1 protease inhibitors designed to be robust against drug resistance.

M.N.Nalam, A.Ali, M.D.Altman, G.S.Reddy, S.Chellappan, V.Kairys, A.Ozen, H.Cao, M.K.Gilson, B.Tidor, T.M.Rana, C.A.Schiffer.

ABSTRACT

Drug resistance mutations in HIV-1 protease selectively alter inhibitor binding without significantly affecting substrate recognition and cleavage. This alteration in molecular recognition led us to develop the substrate-envelope hypothesis which predicts that HIV-1 protease inhibitors that fit within the overlapping consensus volume of the substrates are less likely to be susceptible to drug-resistant mutations, as a mutation impacting such inhibitors would simultaneously impact the processing of substrates. To evaluate this hypothesis, over 130 HIV-1 protease inhibitors were designed and synthesized using three different approaches with and without substrate-envelope constraints. A subset of 16 representative inhibitors with binding affinities to wild-type protease ranging from 58 nM to 0.8 pM was chosen for crystallographic analysis. The inhibitor-protease complexes revealed that tightly binding inhibitors (at the picomolar level of affinity) appear to "lock" into the protease active site by forming hydrogen bonds to particular active-site residues. Both this hydrogen bonding pattern and subtle variations in protein-ligand van der Waals interactions distinguish nanomolar from picomolar inhibitors. In general, inhibitors that fit within the substrate envelope, regardless of whether they are picomolar or nanomolar, have flatter profiles with respect to drug-resistant protease variants than inhibitors that protrude beyond the substrate envelope; this provides a strong rationale for incorporating substrate-envelope constraints into structure-based design strategies to develop new HIV-1 protease inhibitors.