[P004] Poster

1:00 PM - 1:50 PM JST(4:00 AM - 4:50 AM UTC)

[P02-250] Identification of a riboflavin transporter from the hyperthermophilic archaeon Thermococcus kodakarensis

○Kodai Shiotsu¹, Yuko Murayama¹, Yuta Michimori¹, Haruyuki Atomi¹ (1. Kyoto Univ. (Japan))

Keywords:

archaea,transporter,riboflavin

Archaea constitute the third domain of life, and display characteristics not found in bacteria and eukaryotes. Archaea have a unique membrane structure consisting of membrane lipids based on isoprenoids instead of fatty acids. Thermococcus kodakarensis is a hyperthermophilic archaeon that grows optimally at 85℃. Our group has previously sequenced the genome, and also developed a gene manipulation system through which gene disruption, insertion and modification is possible. Although a wealth of information has accumulated on the intracellular metabolism of T. kodakarensis, insight on how transporters contribute to metabolism is still limited. In this study, we focused on riboflavin transport. Riboflavin, a member of the vitamin B group, is converted into active cofactors, such as flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). Flavoproteins that utilize FMN or FAD as coenzymes are found in all domains of life and often play important roles in redox reactions. T. kodakarensis possesses genes related to riboflavin biosynthesis, but the presence of a mechanism to take up riboflavin-related compounds remains unclear.
Within the promoter regions of genes related to riboflavin biosynthesis, a conserved palindromic motif was identified, that might be a binding site for a common transcriptional regulator. A genome-wide search for this motif on the T. kodakarensis genome revealed a similar motif in the promoter region of a gene encoding a hypothetical membrane protein. This hypothetical membrane protein gene, along with a gene encoding a member of the riboflavin biosynthesis pathway, were disrupted and phenotypes were evaluated. Growth properties of these disruption strains in synthetic media with or without riboflavin raised the possibility that the hypothetical membrane protein is involved in the uptake of riboflavin.