Name: Thomas Schoenfeld

Email: tschoenfeld@lucigen.com

Author: Thomas Schoenfeld (1), Nicholas Hermersmann (1), Brian Hedlund (2), Jeremy Dodsworth (2), Vinay Dhodda (1), David Mead (1)

Author affiliation: 1) Lucigen Corporation, Middleton, WI; 2) UNLV, Las Vegas, NV.

Abstract title: Molecular and biochemical diversity of viral replicases from thermal environment

Absstract:

Metagenomic analysis of viral populations has provided a first glimpse into their considerable diversity and has been an important thrust of viral ecology. However, homology-based inferences into the activity of gene products identified in these libraries have generally not been tested biochemically on expressed proteins. In recent work, functional and sequence-based screens of metagenomic libraries from thermal springs in Yellowstone, California and Nevada have identified hundreds of genes for viral replicases, dozens of which have been expressed to produce thermostable enzymes. Several families of viral DNA polymerases have been identified. Although most of these are distinct from knownviral or microbial enzymes, there is unexpected evidence of lateral gene transfer between the viruses and certain Aquificales strains. In some cases, apparent replication operons encoding DNA polymerases and subunits have been isolated on single metagenomic clones. Remarkable biochemical properties of these viral polymerases include reverse transcription activity, high fidelity, proficient strand displacement, and initiation at nicks. Variants of these genes provide insight into adaptationsto high temperatures. For example, significant differences in thermostability among the variants can be attributed to amino acid sequence differences of as little as 3%. Sequence similarities between genes from the viral metagenome and genes of unknown function previously identified in cultivated viruses may reveal the role of the latter. Also abundant in the libraries are helicase and primase genes, the diversity of which will also be discussed.