Amsacta moorei entomopoxvirus encodes a functional esterase (amv133) with protease activity

Lipolytic genes have been investigated in several viral genomes, and some of them show enzyme activity which can be used for various functions including the production of DNA replication metabolites, rescue from endosomes, and membrane fusion. Amsacta moorei entomopoxvirus (AMEV) replicates in nearly the entire insect body, especially in the adipose tissue. One of the open reading frames (ORFs) in the AMEV genome, amv133, encodes a putative lipase enzyme. In this study, we therefore investigate the enzyme activity of amv133.

amv133 was aligned with known lipase genes and their homologs in entomopoxviruses. Expressed proteins were partially purified and assayed for lipase, esterase and protease.

We found that amv133 contains all the domains required for a functional lipase enzyme and that it shows a significant similarity with homologs in other entomopoxviruses. Since there is a similarity of the catalytic triad between lipases and serine proteases, we also investigated the protease activity of amv133. Lipase, esterase and protease assays showed that amv133 encodes a functional esterase enzyme with protease activity.

The current data show that amv133 is a conserved gene in all entomopoxvirus genomes sequenced so far and might contribute greatly to degrading the lipids or proteins and hence improve the virus infection.