|
Basic Characteristics of Mutations
|
|
Mutation Site
|
G431A |
|
Mutation Site Sentence
|
However, when an alternative neutral amino acid (alanine which is the most analogous amino acid to the endogenous glycine;G431A) was introduced into the wild-type virus, replication and syncytia formation was re-established. |
|
Mutation Level
|
Amino acid level |
|
Mutation Type
|
Nonsynonymous substitution |
|
Gene/Protein/Region
|
Env |
|
Standardized Encoding Gene
|
Env
|
|
Genotype/Subtype
|
HIV-1 |
|
Viral Reference
|
gp160 and gp41 HxB2
|
|
Functional Impact and Mechanisms
|
|
Disease
|
Cell line
|
|
Immune
|
Y |
|
Target Gene
|
CD4
|
|
Clinical and Epidemiological Correlations
|
|
Clinical Information
|
- |
|
Treatment
|
- |
|
Location
|
- |
|
Literature Information
|
|
PMID
|
17134507
|
|
Title
|
Second site escape of a T20-dependent HIV-1 variant by a single amino acid change in the CD4 binding region of the envelope glycoprotein
|
|
Author
|
Baldwin CE,Berkhout B
|
|
Journal
|
Retrovirology
|
|
Journal Info
|
2006 Nov 29;3:84
|
|
Abstract
|
BACKGROUND: We previously described the selection of a T20-dependent human immunodeficiency virus type-1 (HIV-1) variant in a patient on T20 therapy. The fusion inhibitor T20 targets the viral envelope (Env) protein by blocking a conformational switch that is critical for viral entry into the host cell. T20-dependent viral entry is the result of 2 mutations in Env (GIA-SKY), creating a protein that undergoes a premature conformational switch, and the presence of T20 prevents this premature switch and rescues viral entry. In the present study, we performed 6 independent evolution experiments with the T20-dependent HIV-1 variant in the absence of T20, with the aim to identify second site compensatory changes, which may provide new mechanistic insights into Env function and the T20-dependence mechanism. RESULTS: Escape variants with improved replication capacity appeared within 42 days in 5 evolution cultures. Strikingly, 3 cultures revealed the same single amino acid change in the CD4 binding region of Env (glycine at position 431 substituted for arginine: G431R). This mutation was sufficient to abolish the T20-dependence phenotype and restore viral replication in the absence of T20. The GIA-SKY-G431R escape variant produces an Env protein that exhibits reduced syncytia formation and reduced cell-cell fusion activity. The escape variant was more sensitive to an antibody acting on an early gp41 intermediate, suggesting that the G431R mutation helps preserve a pre-fusion Env conformation, similar to T20 action. The escape variant was also less sensitive to soluble CD4, suggesting a reduced CD4 receptor affinity. CONCLUSION: The forced evolution experiments indicate that the premature conformational switch of the T20-dependent HIV-1 Env variant (GIA-SKY) can be corrected by a second site mutation in Env (GIA-SKY-G431R) that affects the interaction with the CD4 receptor.
|
|
Sequence Data
|
-
|