Virus yoga: the role of flexibility in virus host cell recognition

Viral capsid proteins and their receptors interact in the context of the virus particle and the plasma membrane to initiate virus entry. For the non-enveloped adenovirus, flexibility in its receptor-binding protein permits receptor binding to occur while avoiding steric constraints that are imposed by the large virus capsids and the cell surface and might also facilitate interaction with secondary receptors. Such flexibility in capsid protein structure is shared by the structurally related reovirus. The presence of hinges in the virus attachment molecule suggests that proper orientation of the receptor-binding site for viral adhesion depends on the flexibility of the receptor or viral ligand, especially for viruses that require the use of multiple receptors.