title: Selection for Protein Kinetic Stability Connects Denaturation Temperatures to Organismal Temperatures and Provides Clues to Archaean Life.
abstract: The relationship between the denaturation temperatures of proteins (Tm values) and the living temperatures of their host organisms (environmental temperatures: TENV values) is poorly understood. Since different proteins in the same organism may show widely different Tm's, no simple universal relationship between Tm and TENV should hold, other than Tm≥TENV. Yet, when analyzing a set of homologous proteins from different hosts, Tm's are oftentimes found to correlate with TENV's but this correlation is shifted upward on the Tm axis. Supporting this trend, we recently reported Tm's for resurrected Precambrian thioredoxins that mirror a proposed environmental cooling over long geological time, while remaining a shocking ~50°C above the proposed ancestral ocean temperatures. Here, we show that natural selection for protein kinetic stability (denaturation rate) can produce a Tm↔TENV correlation with a large upward shift in Tm. A model for protein stability evolution suggests a link between the Tm shift and the in vivo lifetime of a protein and, more specifically, allows us to estimate ancestral environmental temperatures from experimental denaturation rates for resurrected Precambrian thioredoxins. The TENV values thus obtained match the proposed ancestral ocean cooling, support comparatively high Archaean temperatures, and are consistent with a recent proposal for the environmental temperature (above 75°C) that hosted the last universal common ancestor. More generally, this work provides a framework for understanding how features of protein stability reflect the environmental temperatures of the host organisms.
authors.affiliation: Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Granada, 18071, Granada, Spain.
authors.forename: M Luisa
authors.initials: ML
authors.lastname: Romero-Romero
authors.affiliation: Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Granada, 18071, Granada, Spain.
authors.forename: Valeria A
authors.initials: VA
authors.lastname: Risso
authors.affiliation: Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Granada, 18071, Granada, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: Martinez-Rodriguez
authors.affiliation: Georgia Institute of Technology, School of Biology, School of Chemistry and Biochemistry, and Parker H. Petit Institute for Bioengineering and Biosciences, Atlanta, Georgia, 30332, United States of America.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Gaucher
authors.affiliation: Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Granada, 18071, Granada, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Ibarra-Molero
authors.affiliation: Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Granada, 18071, Granada, Spain.
authors.forename: Jose M
authors.initials: JM
authors.lastname: Sanchez-Ruiz
mesh_terms: D001105:Archaea / Q000378:metabolism*; D002152:Calorimetry, Differential Scanning; D003198:Computer Simulation; D007700:Kinetics; D008954:Models, Biological; D011489:Protein Denaturation; D055550:Protein Stability; D058767:Protein Unfolding; D013696:Temperature; D013879:Thioredoxins / Q000737:chemistry* / Q000378:metabolism; D013997:Time Factors
chemical_list: D013879:Thioredoxins