Dinitrogenase-Driven Photobiological Hydrogen Production Combats Oxidative Stress in Cyanothece sp Strain ATCC 51142

作者：Sadler Natalie C; Bernstein Hans C; Melnicki Matthew R; Charania Moiz A; Hill Eric A; Anderson Lindsey N; Monroe Matthew E; Smith Richard D; Beliaev Alexander S; Wright Aaron T

来源：Applied and Environmental Microbiology, 2016, 82(24): 7227-7235.

DOI：10.1128/AEM.02098-16

<jats:title>ABSTRACT</jats:title><jats:p>Photobiologically synthesized hydrogen (H<jats:sub>2</jats:sub>) gas is carbon neutral to produce and clean to combust, making it an ideal biofuel.<jats:named-content content-type="genus-species">Cyanothece</jats:named-content>sp. strain ATCC 51142 is a cyanobacterium capable of performing simultaneous oxygenic photosynthesis and H<jats:sub>2</jats:sub>production, a highly perplexing phenomenon because H<jats:sub>2</jats:sub>evolving enzymes are O<jats:sub>2</jats:sub>sensitive. We employed a system-level<jats:italic>in vivo</jats:italic>chemoproteomic profiling approach to explore the cellular dynamics of protein thiol redox and how thiol redox mediates the function of the dinitrogenase NifHDK, an enzyme complex capable of aerobic hydrogenase activity. We found that NifHDK responds to intracellular redox conditions and may act as an emergency electron valve to prevent harmful reactive oxygen species formation in concert with other cell strategies for maintaining redox homeostasis. These results provide new insight into cellular redox dynamics useful for advancing photolytic bioenergy technology and reveal a new understanding for the biological function of NifHDK.</jats:p><jats:p><jats:bold>IMPORTANCE</jats:bold>Here, we demonstrate that high levels of hydrogen synthesis can be induced as a protection mechanism against oxidative stress via the dinitrogenase enzyme complex in<jats:named-content content-type="genus-species">Cyanothece</jats:named-content>sp. strain ATCC 51142. This is a previously unknown feature of cyanobacterial dinitrogenase, and we anticipate that it may represent a strategy to exploit cyanobacteria for efficient and scalable hydrogen production. We utilized a chemoproteomic approach to capture the<jats:italic>in situ</jats:italic>dynamics of reductant partitioning within the cell, revealing proteins and reactive thiols that may be involved in redox sensing and signaling. Additionally, this method is widely applicable across biological systems to achieve a greater understanding of how cells navigate their environment and how redox chemistry can be utilized to alter metabolism and achieve homeostasis.</jats:p>

• 出版日期2016-12