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Updated: Feb 14, 2026

Measurement of Heme Synthesis Levels in Mammalian Cells
Published on: July 9, 2015
Multi-heme cytochromes provide a pathway for survival in energy-limited environments
Xiao Deng1, Naoshi Dohmae2, Kenneth H Nealson3
1Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656, Japan.
Abstract:
Bacterial reduction of oxidized sulfur species (OSS) is critical for energy production in anaerobic marine subsurfaces. In organic-poor sediments, H2 has been considered as a major energy source for bacterial respiration. We identified outer-membrane cytochromes (OMCs) that are broadly conserved in sediment OSS-respiring bacteria and enable cells to directly use electrons from insoluble minerals via extracellular electron transport. Biochemical, transcriptomic, and microscopic analyses revealed that the identified OMCs were highly expressed on the surface of cells and nanofilaments in response to electron donor limitation. This electron uptake mechanism provides sufficient but minimum energy to drive the reduction of sulfate and other OSS. These results suggest a widespread mechanism for survival of OSS-respiring bacteria via electron uptake from solid minerals in energy-poor marine sediments.
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