Evolutionary adaptations that enable enzymes to tolerate oxidative stress

James A Imlay, Ramakrishnan Sethu, Sanjay Kumar Rohaun

Research output: Contribution to journalReview article

Abstract

Biochemical mechanisms emerged and were integrated into the metabolic plan of cellular life long before molecular oxygen accumulated in the biosphere. When oxygen levels finaly rose, they threatened specific types of enzymes: those that use organic radicals as catalysts, and those that depend upon iron centers. Nature has found ways to ensure that such enzymes are still used by contemporary organisms. In some cases they are restricted to microbes that reside in anoxic habitats, but in others they manage to function inside aerobic cells. In the latter case, it is frequently true that the ancestral enzyme has been modified to fend off poisoning. In this review we survey a range of protein adaptations that permit radical-based and low-potential iron chemistry to succeed in oxic environments. In many cases, accessory domains shield the vulnerable radical or metal center from oxygen. In others, the structures of iron cofactors evolved to less oxidizable forms, or alternative metals replaced iron altogether. The overarching view is that some classes of biochemical mechanism are intrinsically incompatible with the presence of oxygen. The structural modification of target enzymes is an under-recognized response to this problem.

Original languageEnglish (US)
JournalFree Radical Biology and Medicine
DOIs
StatePublished - Jan 1 2019

Fingerprint

Oxidative stress
Oxidative Stress
Iron
Oxygen
Enzymes
Metals
Molecular oxygen
Accessories
Poisoning
Ecosystem
Catalysts
Proteins

Keywords

  • Hydrogen peroxide
  • Iron-sulfur clusters
  • Obligate anaerobiosis
  • Radical enzymes
  • Superoxide

ASJC Scopus subject areas

  • Biochemistry
  • Physiology (medical)

Cite this

Evolutionary adaptations that enable enzymes to tolerate oxidative stress. / Imlay, James A; Sethu, Ramakrishnan; Rohaun, Sanjay Kumar.

In: Free Radical Biology and Medicine, 01.01.2019.

Research output: Contribution to journalReview article

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N2 - Biochemical mechanisms emerged and were integrated into the metabolic plan of cellular life long before molecular oxygen accumulated in the biosphere. When oxygen levels finaly rose, they threatened specific types of enzymes: those that use organic radicals as catalysts, and those that depend upon iron centers. Nature has found ways to ensure that such enzymes are still used by contemporary organisms. In some cases they are restricted to microbes that reside in anoxic habitats, but in others they manage to function inside aerobic cells. In the latter case, it is frequently true that the ancestral enzyme has been modified to fend off poisoning. In this review we survey a range of protein adaptations that permit radical-based and low-potential iron chemistry to succeed in oxic environments. In many cases, accessory domains shield the vulnerable radical or metal center from oxygen. In others, the structures of iron cofactors evolved to less oxidizable forms, or alternative metals replaced iron altogether. The overarching view is that some classes of biochemical mechanism are intrinsically incompatible with the presence of oxygen. The structural modification of target enzymes is an under-recognized response to this problem.

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