Birth of a pathway for sulfur metabolism in early amniote evolution.
Nat Ecol Evol
; 4(9): 1239-1246, 2020 09.
Article
in En
| MEDLINE
| ID: mdl-32601391
ABSTRACT
Among amniotes, reptiles and mammals are differently adapted to terrestrial life. It is generally appreciated that terrestrialization required adaptive changes of vertebrate metabolism, particularly in the mode of nitrogen excretion. However, the current paradigm is that metabolic adaptation to life on land did not involve synthesis of enzymatic pathways de novo, but rather repurposing of existing ones. Here, by comparing the inventory of pyridoxal 5'-phosphate-dependent enzymes in different amniotes, we identify in silico a pathway for sulfur metabolism present in chick embryos but not in mammals. Cysteine lyase contains haem and pyridoxal 5'-phosphate co-factors and converts cysteine and sulfite into cysteic acid and hydrogen sulfide, respectively. A specific cysteic acid decarboxylase produces taurine, while hydrogen sulfide is recycled into cysteine by cystathionine beta-synthase. This reaction sequence enables the formation of sulfonated amino acids during embryo development in the egg at no cost of reduced sulfur. The pathway originated around 300 million years ago in a proto-reptile by cystathionine beta-synthase duplication, cysteine lyase neofunctionalization and cysteic acid decarboxylase co-option. Our findings indicate that adaptation to terrestrial life involved innovations in metabolic pathways, and reveal the molecular mechanisms by which such innovations arose in amniote evolution.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Cystathionine gamma-Lyase
/
Hydrogen Sulfide
Type of study:
Prognostic_studies
Limits:
Animals
Language:
En
Journal:
Nat Ecol Evol
Year:
2020
Document type:
Article
Affiliation country: