Revision as of 03:45, 8 October 2023

MtrC (outer-membrane decaheme c-type cytochrome)

Outer-membrane decaheme c-type cytochrome (MtrC), is involved in the metal reduction with MtrA (periplasmic decaheme c-type cytochrome) and MtrB (outer-membrane porin). All together they form a complex on the outer-membrane surface of the cell which transfers the electrons to the metal oxides. This part is used to catalyze the electron transfer from the outer membrane to the medium.

Usage and Biology

CUG-China 2023--Contribution

We found some interesting information from the articles that explain the function of MtrC in the process of S. oneidensis extracellcular electron transfer. S. oneidensis MR-1 was among the first identified microorganisms capable of using minerals that contain Fe(iii), Mn(iii) or Mn(iv) as terminal electron acceptors3. Genetic studies of this bacterium revealed the direct involvement of six multihaem c-Cyts CymA, Fcc3 (also known as FccA), MtrA, MtrC, OmcA and small tetrahaem cytochrome (STC) — and the porin-like outer membrane protein MtrB in the extracellular reduction of minerals that contain Fe(iii). Functional characterization has confirmed that CymA oxidizes quinol in the cytoplasmic membrane and transfers the released electrons to the periplasmic c-Cyts Fcc3 and STC. Because a mutant without Fcc3 and STC has an impaired ability to reduce Fe(iii) oxides or oxyhydroxides, both Fcc3 and STC are proposed to transport electrons from CymA to MtrA. MtrA, MtrB and MtrC form a trans-outer membrane protein complex that transfers electrons from the periplasmic proteins to the bacterial surface. Finally, on the bacterial surface, MtrC and OmcA can physically interact with each other and transfer electrons directly to minerals that contain Fe(iii), probably through solvent-exposed haems. Notably, MtrC and OmcA also associate with extracellular structures that were previously referred to as ‘nanowires’ . Recent results have demonstrated that nanowires are extensions of the outer membrane that contain MtrC and OmcA and which can make physical connections with neighbouring cells. These outer membrane extensions are proposed to mediate the transfer of electrons to minerals and other S. oneidensis MR-1 cells through a multistep hopping mechanism.

This contribution was added by CUG-China 2023.

Fig. Metal reducing pathways (Mtr) of S. oneidensis

[1] Yidan Hu, Wang Yinghui, Han Xi, et al. Biofilm Biology and Engineering of Geobacter and Shewanella spp. for Energy Applications[J]. Frontiers in Bioengineering and Biotechnology, 2021, 9. [2] Liang Shi, Dong Hailiang, Reguera Gemma, et al. Extracellular electron transfer mechanisms between microorganisms and minerals[J]. Nature Reviews Microbiology, 2016, 14(10): 651-662.

Sequence and Features