Modulation of retroviral restriction and proteasome inhibitor-resistant turnover by changes in the TRIM5alpha B-box 2 domain.
An intact B-box 2 domain is essential for the antiretroviral activity of TRIM5alpha. We modeled the structure of the B-box 2 domain of TRIM5alpha based on the existing three-dimensional structure of the B-box 2 domain of human TRIM29. Using this model, we altered the residues predicted to be exposed on the surface of this globular structure. Most of the alanine substitutions in these residues exerted little effect on the antiretroviral activity of human TRIM5alphahu or rhesus monkey TRIM5alpharh. However, alteration of arginine 119 of TRIM5alphahu or the corresponding arginine 121 of TRIM5alpharh diminished the abilities of the proteins to restrict retroviral infection without affecting trimerization or recognition of the viral capsid. The abilities of these functionally defective TRIM5alpha proteins to accelerate the uncoating of the targeted retroviral capsid were abolished. Removal of the positively charged side chain from B-box 2 arginines 119/120/121 resulted in diminished proteasome-independent turnover of TRIM5alpha and the related restriction factor TRIMCyp. However, testing of an array of mutants revealed that the rapid turnover and retroviral restriction functions of this B-box 2 region are separable.
Diaz-Griffero
Felipe
F
Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA.
Kar
Alak
A
Perron
Michel
M
Xiang
Shi-Hua
SH
Javanbakht
Hassan
H
Li
Xing
X
Sodroski
Joseph
J
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D000090103:Antiviral Restriction Factors; D001120:Arginine / Q000737:chemistry / Q000235:genetics; D002213:Capsid / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D008253:Macaca mulatta; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011480:Protease Inhibitors / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D061988:Proteasome Inhibitors; D017434:Protein Structure, Tertiary; D012190:Retroviridae / Q000378:metabolism*; D000070584:Tripartite Motif Proteins; D044767:Ubiquitin-Protein Ligases
D000090103:Antiviral Restriction Factors; D002352:Carrier Proteins; D011480:Protease Inhibitors; D061988:Proteasome Inhibitors; D000070584:Tripartite Motif Proteins; D001120:Arginine; C477346:TRIM5 protein, human; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex