Researchers at the University Of Colorado Denver School Of Medicine have suggested that new understanding about the adaptive evolution in snake proteins may give scientists an insight into human metabolic function and physiology.
They said that their findings may enable researchers to understand how other animals including humans accomplish aerobic respiration, and may also reveal details about protein function and evolution important for human health.
Earlier snakes were recommended as an ideal model system to study evolution, and results of this new study also support that idea, showing that their use as a model system can even extend to the molecular level.
In the last decade, it was shown that snakes have remarkable abilities to regulate heart and digestive system development and they endure among the most extreme shifts in aerobic metabolism known in vertebrates. This clearly makes snakes an excellent model for studying organ development, as well as physiological and metabolic regulation. But, this uniqueness of snakes has not been reasoned previously at the molecular level.
In this study, David Pollock, PhD, associate professor of biochemistry and molecular genetics at the UC Denver School of Medicine, and his colleagues provide evidence that the major evolutionary changes that have occurred in snakes, such as adaptations for their extreme physiology and metabolic demands, loss of limbs and the evolution of deadly venoms, was accompanied by massive functional redesign of core metabolic proteins.
While molecular explanations for physiological adaptations have been rare, the researchers have shown that some proteins in snakes have endured a remarkable process of evolutionary redesign that may explain why snakes have such special metabolism and physiology. This resulted in alteration of amino acids that are normally highly conserved in these proteins, affecting key molecular functions.
Besides an accelerated burst of amino acid replacements, evidence for adaptation comes from very high levels of molecular co-evolution and convergence at the functional core of these proteins.
"The molecular evolutionary results are remarkable, and set a new precedence for extreme protein evolutionary adaptive redesign. This represents the most dramatic burst of protein evolution in an otherwise highly conserved protein that I know of," said Pollock.
By integrating analyses of molecular evolution with protein structural data, it was shown that critical functions of mitochondrial proteins have been fundamentally altered during the evolution of snakes.
"Snakes are an invaluable resource for evolutionary biologists, structural biologists and biochemists who can use comparative genomics to generate hypotheses for how proteins function, and how these functions may be altered and redesigned. From what we have seen so far, snakes may be the single best model system for studying extreme adaptive evolution in vertebrates," said Todd Castoe, PhD, UC Denver School of Medicine, and a lead author on the paper.
The study is published in Public Library of Science (PLoS) ONE journal.