第1128回生物科学セミナー

The Role of Hydrogen Sulfide in Evolution, Oxygen Sensing and Redox Signaling

Prof. Kenneth R. Olson(Indiana University School of Medicine South Bend)

2017年02月16日(木)    16:50-18:35  理学部2号館 講堂   

In this talk I will make the case that hydrogen sulfide (H2S) is one of the
most versatile and necessary molecules for life. H2S emanating from
hydrothermal vents provided energy, catalytic activity and the structural
backbone for the origin of life in an anoxic world 3.8 billion years ago (bya).
Within a few hundred million years organisms developed the capacity for
anoxigenic photosynthesis and a strong case can be made that H2S was
the first substrate. Eukaryotes appeared around 1.5 bya and evolved in
anoxic-sulfidic oceans for nearly another billion years before oxigenic
photosynthesis oxidized the oceans and the atmosphere to present day
levels. Oxygen toxicity during this period is often regarded as a threat to all
life, necessitating development of elaborate antioxidant mechanisms
against reactive oxygen species (ROS). However, I will make the case that
“antioxidant” mechanisms evolved shortly after life’s origin to deal with
reactive sulfide species (RSS) and they have retained this capacity to the
present. I will show that ROS and RSS are chemically and biologically
similar and I will propose that the current concepts of ROS signaling and
toxicity may actually be due to RSS and that the fad of antioxidant
supplementation by humans is not only useless but may have adverse
consequences. Modern animals have retained the capacity to metabolize
H2S and I will show how this is utilized to detect and respond to oxygen
availability.

参考文献
Olson, KR, Staub, KD. The Role of Hydrogen Sulfide in Evolution and the Evolution of Hydrogen
Sulfide in Metabolism and Signaling Physiology 31: 60-72. DOI: 10.1152/physiol.00024.2015
Olson, KR. Hydrogen Sulfide as an Oxygen Sensor. Antioxidant Redox Signaling 22:377-397.
DOI: 10.1089/ars.2014.5930