Non-metabolic role of alpha-enolase in virus replication.

Viruses are extremely complex and highly evolving microorganisms; thus, it is difficult to analyse them in detail. The virion is believed to contain all the essential components required from its entry to the establishment of a successful infection in a susceptible host cell. Hence, the virion composition is the principal source for its transmissibility and immunogenicity. A virus is completely dependent on a host cell for its replication and progeny production. Occasionally, they recruit and package host proteins into mature virion. These incorporated host proteins are believed to play crucial roles in the subsequent infection, although the significance and the molecular mechanism regulated are poorly understood. One such host protein which is hijacked by several viruses is the glycolytic enzyme, Enolase (Eno-1) and is also packaged into mature virion of several viruses. This enzyme exhibits a highly flexible nature of functions, ranging from metabolic to several non-metabolic activities. All the glycolytic enzymes are known to be moonlighting proteins including enolase. The non-metabolic functions of this moonlighting protein are also highly diverse with respect to its cellular localization. Although very little is known about the virological significance of this enzyme, several of its non-metabolic functions have been observed to influence the virus replication cycle in infected cells. In this review, we have attempted to provide a comprehensive picture of the non-metabolic role of Eno-1, its significance in the virus replication cycle and to stimulate interest around its scope as a therapeutic target for treating viral pathologies.