scholarly journals The Hypervariable Domain of the Murine Leukemia Virus Surface Protein Tolerates Large Insertions and Deletions, Enabling Development of a Retroviral Particle Display System

1999 ◽  
Vol 73 (3) ◽  
pp. 1802-1808 ◽  
Author(s):  
Samuel C. Kayman ◽  
Han Park ◽  
Maya Saxon ◽  
Abraham Pinter
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Single Chain ◽  
Virus Surface ◽  
Insertions And Deletions ◽  
N Terminus ◽  
Murine Leukemia

ABSTRACT The surface proteins (SU) of murine type-C retroviruses have a central hypervariable domain devoid of cysteine and rich in proline. This 41-amino-acid region of Friend ecotropic murine leukemia virus SU was shown to be highly tolerant of insertions and deletions. Viruses in which either the N-terminal 30 amino acids or the C-terminal 22 amino acids of this region were replaced by the 7-amino-acid sequence ASAVAGA were fully infectious. Insertions of this 7-amino-acid sequence at the N terminus, center, and the C terminus of the hypervariable domain had little effect on envelope protein (Env) function, while this insertion at a position 10 amino acids following the N terminus partially destabilized the association between the SU and transmembrane subunits of Env. Large, complex domains (either a 252-amino-acid single-chain antibody binding domain [scFv] or a 96-amino-acid V1/V2 domain of HIV-1 SU containing eight N-linked glycosylation sites and two disulfides) did not interfere with Env function when inserted in the center or C-terminal portions of the hypervariable domain. The scFv domain inserted into the C-terminal region of the hypervariable domain was shown to mediate binding of antigen to viral particles, demonstrating that it folded into the active conformation and was displayed on the surface of the virion. Both positive and negative enrichment of virions expressing the V1/V2 sequence were achieved by using a monoclonal antibody specific for a conformational epitope presented by the inserted sequence. These results indicated that the hypervariable domain of Friend ecotropic SU does not contain any specific sequence or structure that is essential for Env function and demonstrated that insertions into this domain can be used to extend particle display methodologies to complex protein domains that require expression in eukaryotic cells for glycosylation and proper folding.

Amino-terminal amino acid sequence and carboxyl-terminal analysis of Rauscher murine leukemia virus glycoproteins

Virology ◽  
1978 ◽  
Vol 85 (1) ◽  
pp. 319-322 ◽  
Author(s):  
Louis E. Henderson ◽  
Terry D. Copeland ◽  
Gary W. Smythers ◽  
Hans Marquardt ◽  
Stephen Oroszlan
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Terminal Amino Acid ◽  
Amino Terminal ◽  
Terminal Amino ◽  
Carboxyl Terminal ◽  
Murine Leukemia ◽  
Terminal Amino Acid Sequence

scholarly journals Characterizing the Murine Leukemia Virus Envelope Glycoprotein Membrane-Spanning Domain for Its Roles in Interface Alignment and Fusogenicity

2015 ◽  
Vol 89 (24) ◽  
pp. 12492-12500 ◽  
Author(s):  
Daniel J. Salamango ◽  
Marc C. Johnson
Keyword(s):  
Amino Acids ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Tail Domain ◽  
Virus Envelope ◽  
C Terminus ◽  
Viral Glycoproteins ◽  
N Terminus ◽  
Membrane Spanning ◽  
Murine Leukemia

ABSTRACTThe membrane-proximal region of murine leukemia virus envelope (Env) is a critical modulator of its functionality. We have previously shown that the insertion of one amino acid (+1 leucine) within the membrane-spanning domain (MSD) abolished protein functionality in infectivity assays. However, functionality could be restored to this +1 leucine mutant by either inserting two additional amino acids (+3 leucine) or by deleting the cytoplasmic tail domain (CTD) in the +1 leucine background. We inferred that the ectodomain and CTD have protein interfaces that have to be in alignment for Env to be functional. Here, we made single residue deletions to the Env mutant with the +1 leucine insertion to restore the interface alignment (gain of functionality) and therefore define the boundaries of the two interfaces. We identified the glycine-proline pairs near the N terminus (positions 147 and 148) and the C terminus (positions 159 and 160) of the MSD as being the boundaries of the two interfaces. Deletions between these pairs restored function, but deletions outside of them did not. In addition, the vast majority of the single residue deletions regained function if the CTD was deleted. The exceptions were four hydroxyl-containing amino acid residues (T139, T140, S143, and T144) that reside in the ectodomain interface and the proline at position 148, which were all indispensable for functionality. We hypothesize that the hydroxyl-containing residues at positions T139 and S143 could be a driving force for stabilizing the ectodomain interface through formation of a hydrogen-bonding network.IMPORTANCEThe membrane-proximal external region (MPER) and membrane-spanning domains (MSDs) of viral glycoproteins have been shown to be critical for regulating glycoprotein fusogenicity. However, the roles of these two domains are poorly understood. We report here that point deletions and insertions within the MPER or MSD result in functionally inactive proteins. However, when the C-terminal tail domain (CTD) is deleted, the majority of the proteins remain functional. The only residues that were found to be critical for function regardless of the CTD were four hydroxyl-containing amino acids located at the C terminus of the MPER (T139 and T140) and at the N terminus of the MSD (S143 and T144) and a proline near the beginning of the MSD (P148). We demonstrate that hydrogen-bonding at positions T139 and S143 is critical for protein function. Our findings provide novel insights into the role of the MPER in regulating fusogenic activity of viral glycoproteins.

scholarly journals Retroviral Capsid Determinants of Fv1 NB and NR Tropism

2004 ◽  
Vol 78 (18) ◽  
pp. 9592-9598 ◽  
Author(s):  
Anthony Stevens ◽  
Michael Bock ◽  
Scott Ellis ◽  
Paul LeTissier ◽  
Kate N. Bishop ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Naturally Occurring ◽  
Binding Surface ◽  
Loss Of Susceptibility ◽  
Murine Leukemia ◽  
Specificity Determinants ◽  
Ca Protein

ABSTRACT The specificity determinants for susceptibility to resistance by the Fv1 n and b alleles map to amino acid 110 of the murine leukemia virus CA protein. To study the interaction between Fv1 and CA, we examined changes in CA resulting in the loss of susceptibility to Fv1 resistance in naturally occurring NB- and NR-tropic viruses. A variety of amino acid changes affecting Fv1 tropism were identified, at CA positions 82, 92 to 95, 105, 114, and 117, and they all were mapped to the apparent exterior of virion-associated CA. These amino acids may form a binding surface for Fv1.

scholarly journals Mutant murine leukemia virus Gag proteins lacking proline at the N-terminus of the capsid domain block infectivity in virions containing wild-type Gag

Virology ◽  
2006 ◽  
Vol 347 (2) ◽  
pp. 364-371 ◽  
Author(s):  
S.J. Rulli ◽  
D. Muriaux ◽  
K. Nagashima ◽  
J. Mirro ◽  
M. Oshima ◽  
...  
Keyword(s):  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Wild Type ◽  
Gag Proteins ◽  
N Terminus ◽  
Domain Block ◽  
Murine Leukemia
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