Summary
The SARS related Coronavirus genome contains a variety of novel accessory genes. One of these, called ORF7a or ORF8, code for a protein, known as 7a, U122 or X4. We set out to determine the three-dimensional structure of the soluble ectodomain of this type-I transmembrane protein by nuclear magnetic resonance spectroscopy. The fold of the protein is the first member of a further variation of the immunoglobulin like beta-sandwich fold. Because X4 does not reveal significant sequence homologies to proteins in the data bases, we carried out a structure based similarity search for proteins with known function. High structural similarity to Dl domains of ICAM-1 and ICAM-2, and common features in amino acid sequence between X4 and ICAM-1, suggest X4 to possess binding activity for the \(\alpha_{\rm L}\) integrin I domain of LFA-1. Further, based on this structure based prediction, potential functions of X4 in virus replication and pathogenesis are discussed.
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The authors Karen Hänel and Thomas Stangler contributed equally to work.
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Hänel, K., Stangler, T., Stoldt, M. et al. Solution structure of the X4 protein coded by the SARS related coronavirus reveals an immunoglobulin like fold and suggests a binding activity to integrin I domains. J Biomed Sci 13, 281–293 (2006). https://doi.org/10.1007/s11373-005-9043-9
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DOI: https://doi.org/10.1007/s11373-005-9043-9