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Single amino acid insertion in loop 4 confers amphotropic murine leukemia virus receptor function upon murine Pit1
M D Lundorf1, F S Pedersen, B O'Hara
1Department of Molecular and Structural Biology, University of Aarhus, Aarhus C, Denmark.
Abstract:
Pit1 is the human receptor for gibbon ape leukemia virus (GALV) and feline leukemia virus subgroup B (FeLV-B), while the related human protein Pit2 is a receptor for amphotropic murine leukemia virus (A-MuLV). The A-MuLV-related isolate 10A1 can utilize both Pit1 and Pit2 as receptors. A stretch of amino acids named region A was identified in Pit1 (residues 550 to 558 in loop 4) as critical for GALV and FeLV-B receptor function. We have here investigated the role of region A in A-MuLV and 10A1 entry. Insertion of a single amino acid in region A of mouse Pit1 resulted in a functional A-MuLV receptor, showing that region A plays a role in A-MuLV infection. Moreover, the downregulation of 10A1 receptor function by changes in region A of human Pit1 indicates that this region is also involved in 10A1 entry. Therefore, region A seems to play a role in infection by all viruses utilizing Pit1 and/or Pit2 as receptors.
Insights
Region A in Pit1 receptors is crucial for viral entry. Modifications in this region affect infection by gibbon ape leukemia virus (GALV), feline leukemia virus subgroup B (FeLV-B), and amphotropic murine leukemia virus (A-MuLV).
Area of Science:
- Virology
- Molecular Biology
- Cellular Receptors
Background:
- Pit1 and Pit2 are human receptors for various retroviruses, including gibbon ape leukemia virus (GALV), feline leukemia virus subgroup B (FeLV-B), and amphotropic murine leukemia virus (A-MuLV).
- A specific amino acid sequence, region A (residues 550-558 in loop 4 of Pit1), was previously identified as essential for GALV and FeLV-B receptor function.
Purpose of the Study:
- To investigate the role of region A in the viral entry mediated by Pit1 and Pit2.
- To determine if region A is involved in the infection of amphotropic murine leukemia virus (A-MuLV) and the related isolate 10A1.
Main Methods:
- Site-directed mutagenesis was used to introduce a single amino acid insertion into region A of mouse Pit1.
- Functional assays were performed to assess the impact of region A modifications on A-MuLV and 10A1 viral entry into cells expressing Pit1 and Pit2.
Main Results:
- Insertion of a single amino acid in region A of mouse Pit1 rendered it a functional receptor for A-MuLV.
- Alterations within region A of human Pit1 led to reduced receptor function for the 10A1 isolate, indicating its involvement in 10A1 entry.
Conclusions:
- Region A plays a significant role in the viral entry process for all viruses that utilize Pit1 and/or Pit2 as receptors.
- This finding highlights region A as a key determinant of host-virus interactions involving Pit1 and Pit2 receptors.