scholarly journals Entry of Amphotropic Murine Leukemia Virus Is Influenced by Residues in the Putative Second Extracellular Domain of Its Receptor, Pit2

1998 ◽  
Vol 72 (6) ◽  
pp. 4956-4961 ◽  
Author(s):  
Betsy D. Leverett ◽  
Karen B. Farrell ◽  
Maribeth V. Eiden ◽  
Carolyn A. Wilson
Keyword(s):  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Critical Role ◽  
Functional Characterization ◽  
Extracellular Domain ◽  
Receptor Function ◽  
Amphotropic Murine Leukemia Virus ◽  
Fold Reduction ◽  
Gibbon Ape Leukemia Virus ◽  
Murine Leukemia

ABSTRACT Human cells express distinct but related receptors for the gibbon ape leukemia virus (GALV) and the amphotropic murine leukemia virus (A-MuLV), termed Pit1 and Pit2, respectively. Pit1 is not able to function as a receptor for A-MuLV infection, while Pit2 does not confer susceptibility to GALV. Previous studies of chimeric receptors constructed by interchanging regions of Pit1 and Pit2 failed to clarify the determinants unique to Pit2 which correlate with A-MuLV receptor function. In order to identify which regions of Pit2 are involved in A-MuLV receptor function, we exchanged the putative second and third extracellular domains of Pit1, either individually or together, with the corresponding regions of Pit2. Our functional characterization of these receptors indicates a role for the putative second extracellular domain (domain II) in A-MuLV infection. We further investigated the influence of domain II with respect to A-MuLV receptor function by performing site-specific mutagenesis within this region of Pit2. Many of the mutations had little or no effect on receptor function. However, the substitution of serine for methionine at position 138 (S138M) in a Pit1 chimera containing domain II of Pit2 resulted in a 1,000-fold reduction in A-MuLV receptor function. Additional mutations made within domain II of the nonfunctional S138M mutant restored receptor function to nearly wild-type efficiency. The high degree of tolerance for mutations as well as the compensatory effect of particular substitutions observed within domain II suggests that an element of secondary structure within this region plays a critical role in the interaction of the receptor with A-MuLV.

scholarly journals Single Amino Acid Insertion in Loop 4 Confers Amphotropic Murine Leukemia Virus Receptor Function upon Murine Pit1

1998 ◽  
Vol 72 (5) ◽  
pp. 4524-4527 ◽  
Author(s):  
Mikkel D. Lundorf ◽  
Finn S. Pedersen ◽  
Bryan O’Hara ◽  
Lene Pedersen
Keyword(s):  
Amino Acid ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Feline Leukemia Virus ◽  
Single Amino Acid ◽  
Receptor Function ◽  
Amphotropic Murine Leukemia Virus ◽  
Gibbon Ape Leukemia Virus ◽  
Murine Leukemia

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.

scholarly journals Identification of an Extracellular Domain within the Human PiT2 Receptor That Is Required for Amphotropic Murine Leukemia Virus Binding

2004 ◽  
Vol 78 (2) ◽  
pp. 595-602 ◽  
Author(s):  
Steven A Feldman ◽  
Karen B. Farrell ◽  
Ravi K. Murthy ◽  
Jill L. Russ ◽  
Maribeth V. Eiden
Keyword(s):  
Murine Leukemia Virus ◽  
Sodium Phosphate ◽  
Leukemia Virus ◽  
Chinese Hamster ◽  
Extracellular Domain ◽  
Virus Binding ◽  
Type Iii ◽  
Amphotropic Murine Leukemia Virus ◽  
Critical Residue ◽  
Murine Leukemia

ABSTRACT Human PiT2 (PiT2) is a multiple-membrane-spanning protein that functions as a type III sodium phosphate cotransporter and as the receptor for amphotropic murine leukemia virus (A-MuLV). Human PiT1 (PiT1), another type III sodium phosphate cotransporter, is a highly related protein that functions as a receptor for gibbon ape leukemia virus but not for A-MuLV. The ability of PiT1 and PiT2 to function as discrete viral receptors with unique properties presumably is reflected in critical residue differences between these two proteins. Early efforts to map the region(s) within PiT2 that is important for virus binding and/or entry relied on infection results obtained with PiT1-PiT2 chimeric cDNAs expressed in Chinese hamster ovary (CHOK1) cells. These attempts to localize the PiT2 virus-binding site were hampered because they were based on infectivity, not binding, assays, and therefore, receptors that bound but failed to facilitate virus entry could not be distinguished from receptors that did not bind virus. Using a more accurate topological model for PiT2 as well as an A-MuLV receptor-binding assay, we have identified extracellular domain one (ECD1) of the human PiT2 receptor as being important for A-MuLV binding and infection.

scholarly journals The Central Half of Pit2 Is Not Required for Its Function as a Retroviral Receptor

2004 ◽  
Vol 78 (17) ◽  
pp. 9564-9567 ◽  
Author(s):  
Pernille Bøttger ◽  
Lene Pedersen
Keyword(s):  
Amino Acids ◽  
Murine Leukemia Virus ◽  
Deletion Mutant ◽  
Leukemia Virus ◽  
Receptor Function ◽  
Type Iii ◽  
Amphotropic Murine Leukemia Virus ◽  
Sodium Dependent ◽  
Retroviral Receptor ◽  
Murine Leukemia

ABSTRACT The type III sodium-dependent phosphate (NaPi) cotransporter, Pit2, is a receptor for amphotropic murine leukemia virus (A-MuLV) and 10A1 MuLV. In order to determine what is sufficient for Pit2 receptor function, a deletion mutant lacking about the middle half of the protein was made. The mutant supported entry for both viruses, unequivocally narrowing down the identification of the sequence that is sufficient to specify the receptor functions of Pit2 to its N-terminal 182 amino acids and C-terminal 170 amino acids.

scholarly journals Amphotropic Murine Leukemia Virus Entry Is Determined by Specific Combinations of Residues from Receptor Loops 2 and 4

1999 ◽  
Vol 73 (4) ◽  
pp. 3169-3175 ◽  
Author(s):  
Mikkel D. Lundorf ◽  
Finn S. Pedersen ◽  
Bryan O’Hara ◽  
Lene Pedersen
Keyword(s):  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Membrane Topology ◽  
Chimeric Proteins ◽  
Receptor Function ◽  
Amphotropic Murine Leukemia Virus ◽  
Extracellular Loops ◽  
Loop 2 ◽  
Murine Leukemia

ABSTRACT Pit2 is the human receptor for amphotropic murine leukemia virus (A-MuLV); the related human protein Pit1 does not support A-MuLV entry. Interestingly, chimeric proteins in which either the N-terminal or the C-terminal part of Pit2 was replaced by the Pit1 sequence all retained A-MuLV receptor function. A possible interpretation of these observations is that Pit1 harbors sequences which can specify A-MuLV receptor function when presented in a protein context other than Pit1, e.g., in Pit1-Pit2 hybrids. We reasoned that such Pit1 sequences might be identified if presented in the Neurospora crassa protein Pho-4. This protein is distantly related to Pit1 and Pit2, predicted to have a similar membrane topology with five extracellular loops, and does not support A-MuLV entry. We show here that introduction of the Pit1-specific loop 2 sequence conferred A-MuLV receptor function upon Pho-4. Therefore, we conclude that (i) a functional A-MuLV receptor can be constructed by combining sequences from two proteins each lacking A-MuLV receptor function and that (ii) a Pit1 sequence can specify A-MuLV receptor function when presented in another protein context than that provided by Pit1 itself. Previous results indicated a role of loop 4 residues in A-MuLV entry, and the presence of a Pit2-specific loop 4 sequence was found here to confer A-MuLV receptor function upon Pho-4. Moreover, the introduction of a Pit1-specific loop 4 sequence, but not of a Pit2-specific loop 4 sequence, abolished the A-MuLV receptor function of a Pho-4 chimera harboring the Pit1-specific loop 2 sequence. Together, these data suggest that residues in both loop 2 and loop 4 play a role in A-MuLV receptor function. A-MuLV is, however, not dependent on the specific Pit2 loop 2 and Pit2 loop 4 sequences for entry; rather, the role played by loops 2 and 4 in A-MuLV entry can be fulfilled by several different combinations of loop 2 and loop 4 sequences. We predict that the residues in loops 2 and 4, identified in this study as specifying A-MuLV receptor function, are to be found among those not conserved among Pho-4, Pit1, and Pit2.

scholarly journals 536. Dual-Vector Prodrug Activator Gene Therapy Using Retroviral Replicating Vectors Derived from Amphotropic Murine Leukemia Virus and Gibbon Ape Leukemia Virus

2015 ◽  
Vol 23 ◽  
pp. S215
Author(s):  
Shuji Kubo ◽  
Misato Takagi-Kimura ◽  
Christopher R. Logg ◽  
Kip Hermann ◽  
Noriyuki Kasahara
Keyword(s):  
Gene Therapy ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Dual Vector ◽  
Amphotropic Murine Leukemia Virus ◽  
Gibbon Ape Leukemia Virus ◽  
Murine Leukemia
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