Bioprospecting potential of halogenases from Arctic marine actinomycetes

Li Liao, Ruiqin Chen, Ming Jiang, Xiaoqing Tian, Huan Liu, Yong Yu, Chenqi Fan, Bo Chen

Halometabolites, an important group of natural products, generally require halogenases for their biosynthesis. Actinomycetes from the Arctic Ocean have rarely been investigated for halogenases and their gene clusters associated, albeit great potential of halometabolite production has been predicted. Therefore, we initiated this research on the screening of halogenases from Arctic marine actinomycetes isolates to explore their genetic potential of halometabolite biosynthesis. Nine halogenase genes were discovered from sixty Arctic marine actinomycetes using in-house designed or previously reported PCR primers. Four representative genotypes were further cloned to obtain full coding regions through genome walking. The resulting halogenases were predicted to be involved in halogenation of indole groups, antitumor agent ansamitocin-like substrates, or unknown peptide-like compounds. Genome sequencing revealed a potential gene cluster containing the halogenase predicted to catalyze peptide-like compounds. However, the gene cluster was probably silent under the current conditions. PCR-based screening of halogenase genes is a powerful and efficient tool to conduct bioprospecting of halometabolite-producing actinomycetes from the Arctic. Genome sequencing can also identify cryptic gene clusters potentially producing new halometabolites, which might be easily missed by traditional isolation and chemical characterization. In addition, our study indicates that great genetic potential of new halometabolites can be expected from mostly untapped actinomycetes from the polar regions.