Introduction: The substitution of F (S40F), where TCC = S to TTC = F, does not alter the sequence of the overlapping pol frame (TTC = F in the WT to TTT = F) but had an impact on several aspects of gag function.
Introduction: Two substitutions that occurred at the same residue, S40F and S40A, were further investigated by engineering the individual substitutions into an HIV genome (pNL4-3).
Method: Plasmids encoding pNL4-3 Env, pNL4-3-S40A or pNL4-3-S40F, and l-maltose binding protein (MBP)-FLAG-p6*-PR-HA have been previously described.
Result: As noted above, the S40F mutation does not alter
Mutation of the highly conserved Ser-40 of the HIV-1 p6 gag protein to Phe causes the formation of a hydrophobic patch, enhances membrane association, and polyubiquitination of Gag.
Result: Furthermore, these results confirm that these K48-linked polyubiquitinated Gag species even participate in Gag assembly process for all variants, wt, PTAP, S40F, though at different levels.
Result: HeLa cells stably expressing the murine MHC-I allotype H2-Kb (HeLa-Kb,) were transfected with expression plasmids coding for Gag-SL, PTAP-SL, S40F-SL and S40F/ PTAP-SL.
Result: However, analyses of the cell-associated Gag ubiquitination revealed that none of the conservative mutants, S40N or S40D, can increase Gag ubiquitination as it was observed for the S40F mutant (Figure 3A).
Re-visiting the functional Relevance of the highly conserved Serine 40 Residue within HIV-1 p6(Gag).
Result: Furthermore, enhanced membrane binding affinity of a synthetic p6 C-terminal fragment was observed in vitro upon substitution of Ser40 by Phe or upon adding a phosphate group to this residue.
Result: However, wild-type release, polyprotein processing and infectivity of all variants studied here except for S40F suggest that neither S40 nor its phosphorylation is needed for fully functional membrane binding of Gag.
Result: In contrast, previous studies had reported that an S40F change in p6Gag impaired proteolytic maturation of Gag, reduced viral infectivity and delayed replication in T-cell lines.
Result: In line with published results, infectivity was severely decreased for the S40F variant with a similar reduction as obser
The S40 residue in HIV-1 Gag p6 impacts local and distal budding determinants, revealing additional late domain activities.
Abstract: S40F mutation also resulted in stronger Gag-Alix interaction, as detected by yeast 2-hybrid assay.
Abstract: Interestingly, introduction of S40F partially rescued the negative effects on budding of CA NTD mutations EE75,76AA and P99A, which both prevent membrane curvature and therefore block budding at an early stage.
Abstract: The S40F-mediated release defects were exacerbated when the viral-encoded protease (PR) was inactivated or when L domain-1 function was disrupted or when budding was almost completely obliterated by the disruption of both L domain-1 and -2.
Introduction: In this report, we confirm that the S40F mutation results in defects in p
Highly conserved serine residue 40 in HIV-1 p6 regulates capsid processing and virus core assembly.
Figure: (A) 293T cells were cotransfected with HIV-1DeltaPTAP or HIV-1DeltaPTAP/S40F and increasing amount of ALIX plasmid.
Figure: (A) Electron micrographs showing thin sections of HeLa SS6 derived extra cellular particles of HIV-1NL-43 wt, the S40F mutant, the CA-SP1 Gag cleavage deficient mutant CA5, and the ALIX binding site mutant DeltaYP.
Figure: (A) Phosphorimages of SDS-PAGE gels of immunoprecipitations of 35S pulse-chase-labeled Gag protein immunoprecipitates are presented for cell and viral lysates from HeLa cells transiently transfected with either pNLenv or pNLenv S40F.
Figure: (B) Overexpression of ALIX does not rescue infectivity of the S40F
HIV mutation literature information.
PMID: 
2016
Retrovirology
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