Secretion and maturation of multiheme cytochromes in iron-reducing bacteria

• Project/Area Number: 26850052
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Applied microbiology
• Research Institution: University of Miyazaki
• Principal Investigator: Inoue Kengo 宮崎大学, 農学部, 准教授 (70581304)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Project Status: Completed (Fiscal Year 2015)
• Budget Amount: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000); Fiscal Year 2015: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000); Fiscal Year 2014: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
• Keywords: 鉄還元菌 / Geobacter / 細胞外電子伝達 / Ⅱ型分泌システム / シトクロムc / ヘム修飾 / c型シトクロム

Outline of Final Research Achievements

Geobacter sulfurreducens is a key player in current production by mixed-culture microbial fuel cells. Among known essential genes for optimal current production, omcZ is the only c-type cytochrome. To reveal the molecular mechanisms of OmcZ secretion and maturation process, we have investigated type-II secretion system (T2SS) by which OmcZ is proposed to be secreted. In G. sulfurreducens genome, there are two T2SS gene clusters (T2SS-I and -II, respectively). We generated disruption mutants of these T2SS-related genes and investigated their cytochrome production and capability of current production in microbial fuel cell. According to the cytochrome production profile results, T2SS-I disrupted mutant could not produce maturated OmcZ but T2SS-II disrupted mutant did not show difference from wild-type G. sulfurreducens strain. However, both mutants could produce current in microbial fuel cell as well as wild-type.

Research Products

• [Journal Article] Uptake of self-secreted flavins as bound cofactors for extracellular electron transfer in Geobacter species (2014)
  • Author(s): Akihiro Okamoto, Koichiro Saito, Kengo Inoue, Kenneth H. Nealson, Kazuhito Hashimoto, Ryuhei Nakamura
  • Journal Title: Energy Environ. Sci. Volume: 7 Issue: 4 Pages: 1357-1361
  • DOI: 10.1039/c3ee43674h
  • Peer Reviewed / Open Access
• [Journal Article] Structural Basis of the Divergent Oxygenation Reactions Catalyzed by the Rieske Nonheme Iron Oxygenase Carbazole 1,9a-Dioxygenase (2014)
  • Author(s): Kengo Inoue, Yusuke Usami, Yuji Ashikawa, Haruko Noguchi, Takashi Umeda, Aiko Yamagami-Ashikawa, Tadafumi Horisaki, Hiromasa Uchimura, Tohru Terada, Shugo Nakamura, Kentaro Shimizu, Hiroshi Habe, Hisakazu Yamane, Zui Fujimoto and Hideaki Nojiri
  • Journal Title: Applied and Environmental Microbiology Volume: Volume 80 Issue: 9 Pages: 2821-2832
  • DOI: 10.1128/aem.04000-13
  • Peer Reviewed / Open Access