TABLE 2.
Phenotypes of TRIM5α B-box 2 mutants
TRIM5αrh variant | Restrictiona
|
Mean reverse transcription (%) ± SDb,h | Dimerizationc,h | Higher-order association (%)d,h
|
Mean binding to HIV-1 CA-NC complexes ± SDe,h | Localizationf | Half-life (min)g | ||
---|---|---|---|---|---|---|---|---|---|
HIV-1 | N-MLV | Association with wild type | Self-association | ||||||
Wild type | ++++ | ++ | 0 | Yes | 100 | 100 | 1 ± 0 | Wild-type | 48 |
E120D | ++++ | + | 0 | ND | 100 | ND | 1.26 ± 0.05 | L reticular | 80 |
L104E | ++++ | + | 0 | Yes | ND | ND | 1.09 ± 0.29 | L reticular | >1,000 |
K93A | ++++ | + | 0 | Yes | ND | ND | 1.23 ± 0.04 | Wild-type | 60 |
Q92A | ++++ | + | 0 | Yes | ND | ND | 1.14 ± 0.12 | Wild-type | 65 |
F131E | ++++ | + | ND | ND | ND | ND | 0.84 ± 0.06 | L reticular | 60 |
Q123E | ++++ | - | ND | ND | ND | 73 | 1.00 ± 0.30 | Wild-type | 70 |
R121K | ++++ | - | 0 | ND | 7 | 81 | 1.34 ± 0.07 | Wild-type | 42 |
R99E | ++++ | - | 0 | Yes | ND | 85 | 0.95 ± 0.23 | L reticular | 240 |
K103E | ++++ | - | 0 | ND | ND | ND | 0.90 ± 0.08 | L reticular | >1,000 |
L105E | +++ | - | ND | ND | ND | ND | 1.04 ± 0.16 | Reticular | >1,000 |
E120R/R121E | +++ | - | 56.5 ± 10 | Yes | ND | 15 | 0.76 ± 0.15 | Reticular | >1,000 |
E120D/R121K | +++ | - | 25 ± 11 | ND | 3 | ND | 1.12 ± 0.24 | Reticular | 400 |
E120K/R121K | +++ | - | ND | ND | 0 | 70 | 0.71 ± 0.12 | L reticular | 110 |
L132E | +++ | - | 63.5 ± 7 | ND | 0 | 0 | 0.84 ± 0.13 | L reticular | 120 |
E102R | +++ | - | ND | ND | ND | ND | 0.97 ± 0.23 | M reticular | 400 |
E102R/R121E | +++ | - | 81.5 ± 26 | Yes | 0 | 28 | 0.86 ± 0.04 | M reticular | 600 |
E120R | ++ | - | ND | ND | 6 | ND | 0.45 ± 0.12 | M reticular | ND |
E120R/R121K | ++ | - | ND | ND | 0 | 80* | 0.45 ± 0.06 | L reticular | 240 |
E120K | ++ | - | 5 ± 5 | ND | 0 | 14 | 0.84 ± 0.10 | L reticular | 300 |
E102R/E120R/R121E | ++ | - | ND | ND | 0 | ND | ND | L reticular | 400 |
E120D/R121D | ++ | - | ND | Yes | 0 | ND | 0.85 ± 0.06 | L reticular | 360 |
E120R/R121D | ++ | - | 19 ± 11 | ND | 0 | ND | 0.72 ± 0.10 | Reticular | 400 |
E120K/R121E | + | - | ND | Yes | 0 | 5 | 0.73 ± 0.07 | L reticular | >1,000 |
E120K/R121D | + | - | ND | Yes | 0 | 0 | 0.42 ± 0.00 | Reticular | >1,000 |
E120D/R121E | + | - | ND | ND | 0 | 0 | 0.55 ± 0.06 | L reticular | >1,000 |
R121S | + | - | 49 ± 8 | Yes | ND | ND | 0.48 ± 0.13 | Reticular | 340 |
R121Q | + | - | 55 ± 5 | Yes | 0 | ND | 0.54 ± 0.07 | Reticular | 300 |
L118E | + | - | 100 | Yes | 0 | 10 | 0.4 ± 0.03 | Reticular | 240 |
W117E | + | - | 60 | Yes | 6 | 0* | 0.43 ± 0.08 | Reticular | 300 |
R121E | - | - | 100 | Yes | 0 | 0* | 0.43 ± 0.05 | Reticular | >1,000 |
R121D | - | - | 100 | Yes | 0 | 0* | 0.55 ± 0.06 | Reticular | 173 |
Restriction was measured by infecting cells expressing the indicated TRIM5αrh variants with HIV-1 and N-MLV expressing the GFP protein. After 48 h, the percentage of GFP-positive cells (infected cells) was determined by flow cytometry. For HIV-1: ++++, 100% restriction; +++, ∼75% restriction; ++, ∼50% restriction; +, ∼25% restriction; and −, <25% or no restriction. For N-MLV: ++, ∼50% restriction; +, ∼25% restriction; and −, <25% restriction. Experiments were performed at least three times, and typical results are shown.
HIV-1 reverse transcription was measured by real-time PCR 6 h after infection as described in Materials and Methods. The number represents the percentage of late reverse transcripts observed in cells expressing the indicated TRIM5αrh variant relative to the level of late reverse transcripts in control HIV-1-infected cells transduced with the empty LPCX vector. Experiments were performed at least two times.
Dimerization of TRIM5αrh variants was measured by the use of the cross-linker EGS as described in Materials and Methods.
Each TRIM5αrh variant was assayed for higher-order association with wild-type TRIM5αrh (association with wild type) or with itself (self-association), as described in Materials and Methods. In the case of association with wild-type TRIM5αrh, the percentage represents the fraction of the TRIM5αrh variant coprecipitated with wild-type TRIM5αrh relative to the amount of wild-type TRIM5αrh coprecipitated with itself. For self-association, the percentage represents the fraction of the TRIM5αrh variant coprecipitated with itself relative to the coprecipitation of wild-type TRIM5αrh with itself. *, A high background was observed for the TRIM5αrh variant in the control sample without a TRIM5α target protein. The reported values may be less reliable as a result of this background.
Binding to the HIV-1 capsid complexes was determined for each TRIM5αrh variant as described in Materials and Methods. Binding is expressed as the amount of the TRIM5αrh variant bound to HIV-1 capsid complexes divided by the amount of bound wild-type TRIM5αrh at a similar input level. Experiments were repeated at least three times. Note that, because the binding ratios are calculated at input levels at which some binding of the mutant TRIM5αrh protein to the HIV-1 capsid complexes can be detected, these ratios overestimate the relative capsid-binding affinities of the mutant proteins.
The localization of each TRIM5αrh variant was determined as described in Materials and Methods. For each TRIM5αrh variant, cytoplasmic bodies were counted for five independent cells and compared to the number in cells expressing wild-type TRIM5αrh. “L” means fewer cytoplasmic bodies than wild-type TRIM5αrh; “M” means more cytoplasmic bodies than the wild type, and “reticular” indicates a diffuse, reticular pattern of staining throughout the cytoplasm.
The half-life of each TRIM5αrh variant was estimated by pulse-chase experiments. Every experiment was repeated at least two times.
ND, not determined.