Affiliation:
1. Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky 40536-0509
Abstract
ABSTRACT
Paramyxoviruses utilize both an attachment protein and a fusion (F) protein to drive virus-cell and cell-cell fusion. F exists functionally as a trimer of two disulfide-linked subunits: F
1
and F
2
. Alignment and analysis of a set of paramyxovirus F protein sequences identified three conserved blocks (CB): one in the fusion peptide/heptad repeat A domain, known to play important roles in fusion promotion, one in the region between the heptad repeats of F
1
(CBF
1
) (A. E. Gardner, K. L. Martin, and R. E. Dutch, Biochemistry
46
:5094-5105, 2007), and one in the F
2
subunit (CBF
2
). To analyze the functions of CBF
2
, alanine substitutions at conserved positions were created in both the simian virus 5 (SV5) and Hendra virus F proteins. A number of the CBF
2
mutations resulted in folding and expression defects. However, the CBF
2
mutants that were properly expressed and trafficked had altered fusion promotion activity. The Hendra virus CBF
2
Y79A and P89A mutants showed significantly decreased levels of fusion, whereas the SV5 CBF
2
I49A mutant exhibited greatly increased cell-cell fusion relative to that for wild-type F. Additional substitutions at SV5 F I49 suggest that both side chain volume and hydrophobicity at this position are important in the folding of the metastable, prefusion state and the subsequent triggering of membrane fusion. The recently published prefusogenic structure of parainfluenza virus 5/SV5 F (H. S. Yin et al., Nature
439:
38-44, 2006) places CBF
2
in direct contact with heptad repeat A. Our data therefore indicate that this conserved region plays a critical role in stabilizing the prefusion state, likely through interactions with heptad repeat A, and in triggering membrane fusion.
Publisher
American Society for Microbiology
Subject
Virology,Insect Science,Immunology,Microbiology
Reference59 articles.
1. Asano, K., and A. Asano. 1985. Why is a specific amino acid sequence of F glycoprotein required for the membrane fusion reaction between envelope of HVJ (Sendai virus) and target cell membranes? Biochem. Int.10:115-122.
2. Baker, K. A., R. E. Dutch, R. A. Lamb, and T. S. Jardetzky. 1999. Structural basis for paramyxovirus-mediated membrane fusion. Mol. Cell3:309-319.
3. CHEMOKINE RECEPTORS AS HIV-1 CORECEPTORS: Roles in Viral Entry, Tropism, and Disease
4. Bolt, G., and I. R. Pedersen. 1998. The role of subtilisin-like proprotein convertases for cleavage of the measles virus fusion glycoprotein in different cell types. Virology252:387-398.
5. Bossart, K. N., L.-F. Wang, B. Eaton, and C. C. Broder. 2001. Functional expression and membrane fusion tropism of the envelope glycoproteins of Hendra virus. Virology290:121-135.
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