An invariant surface patch on the TRIM5alpha PRYSPRY domain is required for retroviral restriction but dispensable for capsid binding.
TRIM5alpha is a retrovirus restriction factor in the host cell cytoplasm that blocks infection before provirus establishment. Restriction activity requires capsid (CA)-specific recognition by the PRYSPRY domain of TRIM5alpha. To better understand the restriction mechanism, nine charge-cluster-to-triple-alanine mutants in the TRIM5alpha PRYSPRY domain were assessed for CA-specific restriction activity. Five mutants distributed along the TRIM5alpha PRYSPRY primary sequence disrupted restriction activity against N-tropic murine leukemia virus and equine infectious anemia virus. Modeling of the TRIM5alpha PRYSPRY domain based on the crystal structures of PRYSPRY-19q13.4.1, GUSTAVUS, and TRIM21 identified a surface patch where disruptive mutants clustered. All mutants in this patch retained CA-binding activity, a reticular distribution in the cytoplasm, and steady-state protein levels comparable to those of the wild type. Residues in the essential patch are conserved in TRIM5alpha orthologues and in closely related paralogues. The same surface patch in the TRIM18 and TRIM20 PRYSPRY domains is the site of mutants causing Opitz syndrome and familial Mediterranean fever. These results indicate that, in addition to CA-specific binding, the PRYSPRY domain possesses a second function, possibly binding of a cofactor, that is essential for retroviral restriction activity by TRIM5alpha.
Sebastian
Sarah
S
Department of Microbiology, Columbia University, New York, New York 10032, USA.
Grütter
Christian
C
Strambio de Castillia
Caterina
C
Pertel
Thomas
T
Olivari
Silvia
S
Grütter
Markus G
MG
Luban
Jeremy
J
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D000090103:Antiviral Restriction Factors; D001665:Binding Sites; D036022:Capsid Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D006801:Humans; D004860:Infectious Anemia Virus, Equine / Q000276:immunology*; D009052:Leukemia Virus, Murine / Q000276:immunology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D000070584:Tripartite Motif Proteins; D044767:Ubiquitin-Protein Ligases
D000090103:Antiviral Restriction Factors; D036022:Capsid Proteins; D002352:Carrier Proteins; D000070584:Tripartite Motif Proteins; C477346:TRIM5 protein, human; D044767:Ubiquitin-Protein Ligases