A novel bacterial Water Hypersensitivity-like protein shows in vivo protection against cold and freeze damage.

Metagenomic library screening， by functional or sequence analysis， has become an established method for the identification of novel genes and gene products， including genetic elements implicated in microbial stress response and adaptation. We have identified， using a sequence-based approach， a fosmid clone from an Antarctic desert soil metagenome library containing a novel gene which codes for a protein homologous to a Water Hypersensitivity domain (WHy). The WHy domain is typically found as a component of specific LEA (Late Embryogenesis Abundant) proteins， particularly the LEA-14 (LEA-8) variants， which occur widely in plants， nematodes， bacteria and archaea and which are typically induced by exposure to stress conditions. The novel WHy-like protein (165 amino acid， 18.6 kDa) exhibits a largely invariant NPN motif at the N-terminus and has high sequence identity to genes identified in Pseudomonas genomes. Expression of this protein in Escherichia coli significantly protected the recombinant host against cold and freeze stress.