The latest on budding

Abstract

The final stage of assembly of enveloped viruses is release of the particle from the cell surface. A short region within Gag proteins of retroviruses, the late (L) domain, has recently been shown to be required for the late steps of budding. The L domain contains a critical proline-rich sequence [PPPPY in Rous sarcoma virus (RSV)] that mediates binding to proteins containing a WW domain (a 40-residue motif with two conserved tryptophans). Two new reports now document the presence of a functionally related L domain within the M Protein of rhabdoviruses. Harty et al.1xA proline-rich motif within the matrix protein of vesicular stomatitis virus and rabies virus interacts with WW domains of cellular proteins: implications for viral budding. Harty, R.N. et al. J. Virol. 1999; 73: 2921–2929PubMedSee all References1 identify a conserved PPXY motif in the M proteins of vesicular stomatitis virus (VSV) and rabies virus. This motif can bind to WW domains of two cellular proteins (YAP and Nedd4) in vitro. Mutations within the PPXY motif block interaction with WW domains and decrease exocytosis of M proteins in a pseudo-budding assay. Moreover, the amino-terminal region of VSV M protein containing the PPXY motif can replace the L domain of RSV Gag in conferring release of virus-like particles2xLate domain function identified in the vesicular stomatitis virus M protein by use of rhabdovirus–retrovirus chimeras. Craven, R.C. et al. J. Virol. 1999; 73: 3359–3365PubMedSee all References2. These findings highlight similarities between assembly of retroviruses and rhabdoviruses and suggest that interactions with host cell proteins might be involved in the late steps of virus particle budding.