scholarly journals Asymmetric Requirement for Cholesterol in Receptor-Bearing but Not Envelope-Bearing Membranes for Fusion Mediated by Ecotropic Murine Leukemia Virus

2002 ◽  
Vol 76 (13) ◽  
pp. 6701-6709 ◽  
Author(s):  
Xiongbin Lu ◽  
Ying Xiong ◽  
Jonathan Silver
Keyword(s):  
Murine Leukemia Virus ◽  
Mammalian Cells ◽  
Insect Cells ◽  
Leukemia Virus ◽  
Cell System ◽  
Membrane Rafts ◽  
Cell Physiology ◽  
Virus Envelope ◽  
Murine Leukemia

ABSTRACT We show that fusion mediated by ecotropic murine leukemia virus envelope is dependent on cholesterol in receptor-bearing membranes. The effect is >10 times larger in insect cells than mammalian cells, probably because the former can be more extensively depleted of cholesterol. The fact that cholesterol is apparently not needed in envelope-bearing membranes suggests that it plays a role in an asymmetric step in membrane fusion and argues against a class of models in which cholesterol is important in symmetric fusion intermediates. The insect cell system has promise for clarifying the role of membrane rafts in other aspects of cell physiology.

scholarly journals Role of intron-contained sequences in formation of moloney murine leukemia virus env mRNA.

1984 ◽  
Vol 4 (11) ◽  
pp. 2289-2297 ◽  
Author(s):  
L S Hwang ◽  
J Park ◽  
E Gilboa
Keyword(s):  
Splice Site ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Splice Junction ◽  
Moloney Murine Leukemia Virus ◽  
Expression Vectors ◽  
Virus Envelope ◽  
Cellular Genes ◽  
Murine Leukemia

Formation of the Moloney murine leukemia virus envelope mRNA involves the removal of a 5,185-base pair-long intron. Deletion analysis of two Moloney murine leukemia virus-derived expression vectors revealed the existence of two short regions within the viral intron which are required for the efficient formation of the spliced RNA species. One region was present upstream from the 3' splice junction, extended at least 85 nucleotides beyond the splice site, and was not more than 165 nucleotides long. As yeast polymerase II introns, the Moloney murine leukemia virus intron contains the sequence 5'-TACTAAC-3' 15 nucleotides upstream from the 3' splice site. A second region located in the middle of the intron, within a 560-nucleotide-long sequence, was also essential for formation of the spliced RNA species. The efficient splicing of the env mRNA in the absence of expression of viral genes raises the possibility that similar mechanisms are used to remove introns of (some) cellular genes.

Role of intron-contained sequences in formation of moloney murine leukemia virus env mRNA

1984 ◽  
Vol 4 (11) ◽  
pp. 2289-2297
Author(s):  
L S Hwang ◽  
J Park ◽  
E Gilboa
Keyword(s):  
Splice Site ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Splice Junction ◽  
Moloney Murine Leukemia Virus ◽  
Expression Vectors ◽  
Virus Envelope ◽  
Cellular Genes ◽  
Murine Leukemia

Formation of the Moloney murine leukemia virus envelope mRNA involves the removal of a 5,185-base pair-long intron. Deletion analysis of two Moloney murine leukemia virus-derived expression vectors revealed the existence of two short regions within the viral intron which are required for the efficient formation of the spliced RNA species. One region was present upstream from the 3' splice junction, extended at least 85 nucleotides beyond the splice site, and was not more than 165 nucleotides long. As yeast polymerase II introns, the Moloney murine leukemia virus intron contains the sequence 5'-TACTAAC-3' 15 nucleotides upstream from the 3' splice site. A second region located in the middle of the intron, within a 560-nucleotide-long sequence, was also essential for formation of the spliced RNA species. The efficient splicing of the env mRNA in the absence of expression of viral genes raises the possibility that similar mechanisms are used to remove introns of (some) cellular genes.

scholarly journals The Role of the Membrane-spanning Domain Sequence in Glycoprotein-mediated Membrane Fusion

1999 ◽  
Vol 10 (9) ◽  
pp. 2803-2815 ◽  
Author(s):  
Gwen M. Taylor ◽  
David Avram Sanders
Keyword(s):  
Membrane Fusion ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Envelope Proteins ◽  
Viral Fusion ◽  
Virus Envelope ◽  
Membrane Spanning ◽  
Membrane Spanning Domains ◽  
Murine Leukemia

The role of glycoprotein membrane-spanning domains in the process of membrane fusion is poorly understood. It has been demonstrated that replacing all or part of the membrane-spanning domain of a viral fusion protein with sequences that encode signals for glycosylphosphatidylinositol linkage attachment abrogates membrane fusion activity. It has been suggested, however, that the actual amino acid sequence of the membrane-spanning domain is not critical for the activity of viral fusion proteins. We have examined the function of Moloney murine leukemia virus envelope proteins with substitutions in the membrane-spanning domain. Envelope proteins bearing substitutions for proline 617 are processed and incorporated into virus particles normally and bind to the viral receptor. However, they possess greatly reduced or undetectable capacities for the promotion of membrane fusion and infectious virus particle formation. Our results imply a direct role for the residues in the membrane-spanning domain of the murine leukemia virus envelope protein in membrane fusion and its regulation. They also support the thesis that membrane-spanning domains possess a sequence-dependent function in other protein-mediated membrane fusion events.

scholarly journals Sequential activation of the three protomers in the Moloney murine leukemia virus Env

2017 ◽  
Vol 114 (10) ◽  
pp. 2723-2728 ◽  
Author(s):  
Mathilda Sjöberg ◽  
Robin Löving ◽  
Birgitta Lindqvist ◽  
Henrik Garoff
Keyword(s):  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Moloney Murine Leukemia Virus ◽  
Virus Envelope ◽  
Sequential Activation ◽  
Virus Envelope Protein ◽  
Membrane Fusion Proteins ◽  
Viral Membrane Fusion ◽  
Murine Leukemia

Viral membrane fusion proteins of class I are trimers in which the protomeric unit is a complex of a surface subunit (SU) and a fusion active transmembrane subunit (TM). Here we have studied how the protomeric units of Moloney murine leukemia virus envelope protein (Env) are activated in relation to each other, sequentially or simultaneously. We followed the isomerization of the SU-TM disulfide and subsequent SU release from Env with biochemical methods and found that this early activation step occurred sequentially in the three protomers, generating two asymmetric oligomer intermediates according to the scheme (SU-TM)3→ (SU-TM)2TM → (SU-TM)TM2→ TM3. This was the case both when activation was triggered in vitro by depleting stabilizing Ca2+from solubilized Env and when viral Env was receptor triggered on rat XC cells. In the latter case, the activation reaction was too fast for direct observation of the intermediates, but they could be caught by alkylation of the isomerization active thiol.

Heterogeneity of Murine Leukemia Virus in vitro DNA; Detection of Viral DNA in Mammalian Cells

Science ◽  
1971 ◽  
Vol 172 (3990) ◽  
pp. 1353-1355 ◽  
Author(s):  
L. D. Gelb ◽  
S. A. Aaronson ◽  
M. A. Martin
Keyword(s):  
Murine Leukemia Virus ◽  
Mammalian Cells ◽  
Dna Detection ◽  
Leukemia Virus ◽  
Viral Dna ◽  
Murine Leukemia
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