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Title: Solar powered biohydrogen production requires specific localization of the hydrogenase

Cyanobacteria contain a bidirectional [NiFe] hydrogenase which transiently produces hydrogen upon exposure of anoxic cells to light, potentially acting as a “valve” releasing excess electrons from the electron transport chain. However, its interaction with the photosynthetic electron transport chain remains unclear. By GFP-tagging the HoxF diaphorase subunit we show that the hydrogenase is thylakoid associated, comprising a population dispersed uniformly through the thylakoids and a subpopulation localized to discrete puncta in the distal thylakoid. Thylakoid localisation of both the HoxH and HoxY hydrogenase subunits is confirmed by immunogold electron microscopy. The diaphorase HoxE subunit is essential for recruitment to the dispersed thylakoid population, potentially anchoring the hydrogenase to the membrane, but aggregation to puncta occurs through a distinct HoxE-independent mechanism. Membrane association does not require NDH-1. Localization is dynamic on a scale of minutes, with anoxia and high light inducing a significant redistribution between these populations in favour of puncta. Lastly, since HoxE is essential for access to its electron donor, electron supply to the hydrogenase depends on a physiologically controlled localization, potentially offering a new avenue to enhance photosynthetic hydrogen production by exploiting localization/aggregation signals.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [2] ;  [2] ;  [6] ;  [4] ;  [4]
  1. Univ. of Warwick, Coventry (United Kingdom). Systems Biology Centre
  2. Imperial College, London (United Kingdom)
  3. National Renewable Energy Lab. (NREL), Golden, CO (United States); Univ. of Colorado, Boulder, CO (United States)
  4. Queen Mary Univ. of London, London (United Kingdom)
  5. King's College London (United Kingdom)
  6. Univ. of Kiel (Germany)
Publication Date:
OSTI Identifier:
1166649
Report Number(s):
NREL/JA--2700-60384
Journal ID: ISSN 1754-5692; EESNBY
Grant/Contract Number:
AC36-08-GO28308
Type:
Accepted Manuscript
Journal Name:
Energy & Environmental Science
Additional Journal Information:
Journal Volume: 7; Journal Issue: 11; Journal ID: ISSN 1754-5692
Publisher:
Royal Society of Chemistry
Research Org:
National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy Fuel Cell Technologies Office
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; 08 HYDROGEN Chemical and Biosciences; hydrogen; hydrogenase; cyanobacteria