Viral membrane proteins

Abstract

This special issue on ‘Viral membrane proteins’ incorporates a series of research articles that were presented at the ‘Conference on Viral Membrane Proteins’, held at the University of Heidelberg, Germany, on 12–14 December 2008. The aim of the symposium was to involve all areas of research in this emerging Weld focusing on biophysical and clinically relevant approaches as well as on the fundamental science. The interest in viral membrane proteins has diVerent foundations. The most obvious is that viral membrane proteins can serve as targets for a new generation of antiviral drugs. But in addition to this, viral membrane proteins reveal many unique structural and functional features that can provide a blueprint for developing molecular tools for bioand nanotechnology as well as biomedicine. Whilst the membrane proteins of the host comprise up to 50% of all drug targets, this frequency is not yet the case for viral membrane proteins. Today most antiviral drugs target globular proteins with only a few targeting membrane proteins. To highlight some of these membrane proteins: they include entry inhibitors for HIV-1 and inXuenza as well as channel blockers for the latter virus. A better understanding of the role and also of the structure of viral membrane proteins can be anticipated to be directly relevant for the assessment of these proteins as potential drug targets in the very near future. At the current state of knowledge, viral membrane proteins in particular are very likely to become very important drug targets, as an increasing number of companies are dealing with this type of protein. Apart from their role as drug targets, viral membrane proteins also have many other interesting features. They may, for example, serve as templates for unique techniques for proteinaceous systems which enable the delivery of large cargo across the lipid membrane. The “technology” used by the viruses includes fusion and transduction. Some viruses have coupled membrane protein-based sensor systems including proteins that ultimately perform the fusion event. One such coupled protein system is the neuraminidase (sensor)/hemaglutinin (fusion) system of inXuenza. Other viruses such as HIV-1 have non-covalently linked their fusion machinery, gp41, with a sensor protein, gp120, with the latter placed like a backpack on top of the former. A completely diVerent strategy relies on formation of channels and pores that facilitate the Xux of the viral genome into the cell (polio virus, tobacco mosaic virus). In the case of transduction, certain sequences of viral proteins are highly enriched with positively charged amino acids known to facilitate transduction. Used as a short sequence, these positively charged peptides may work as artiWcial vehicles for cargo delivery across the lipid membrane. Whatever one’s interest in viral membrane proteins is, whether it is as a drug target or a shuttle system, the Wrst, most essential step is to achieve a profound understanding of the structural and functional aspects of these proteins. To achieve the necessary level of understanding, a broad range of techniques has to be employed in the investigation of the proteins. Since all techniques cover speciWc time and size W. B. Fischer (&) Institute of Biophotonics, School of Biomedical Science and Engineering, National Yang-Ming University, 155, Sec. 2, Li-Nong St., Taipei 112, Taiwan e-mail: wWscher@ym.edu.tw