Tailspike

Tailspike refers to a structural component found at the distal end of many tailed bacteriophages (viruses that infect bacteria). Tailspikes project from the tail tip and are involved in recognizing and interacting with the surface of bacterial cells. They can function as receptor-binding proteins and, in many cases, as enzymes that modify or degrade surface polysaccharides such as capsules, O-antigens, or other extracellular coatings.

Structure and function often overlap in tailspikes. They are typically produced as separate protein subunits that assemble into spike-like projections at the tail tip. In many phages, tailspikes contain enzymatic domains, classifying them as polysaccharide depolymerases. These enzymatic activities facilitate access to the bacterial cell surface by removing or weakening protective layers, thereby aiding adsorption and genome injection. In other instances, tailspikes primarily mediate specific receptor recognition without strong enzymatic activity.

Impact on host range and infection is significant. Because tailspike proteins determine which bacterial surface features are compatible with successful infection, variation in tailspike genes can expand or shift a phage’s host range. Tailspike genes are often modular and subject to genetic exchange, contributing to phage diversity and adaptation.

Applications and relevance include research into phage therapy and bacterial typing. Tailspike depolymerases have potential use as diagnostic tools to identify bacterial serotypes and as antimicrobial agents that disrupt protective capsules or biofilms. Ongoing studies explore how tailspike diversity shapes phage–bacteria interactions and how tailspikes can be harnessed in biotechnology.