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Volume 2013 (2013), Article ID 680436, 9 pages
Research Article

Comparative Analysis of Barophily-Related Amino Acid Content in Protein Domains of Pyrococcus abyssi and Pyrococcus furiosus

1Evolutionary Bioinformatics Laboratory, Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
2National Center for Supercomputing Applications, Urbana, IL 61801, USA
3Laboratory of Molecular Evolution, Institute of Genetics and Biophysics “Adriano Buzzati-Traverso”, CNR, 80131 Napoli, Italy

Received 4 July 2013; Revised 21 August 2013; Accepted 23 August 2013

Academic Editor: Kyung Mo Kim

Copyright © 2013 Liudmila S. Yafremava et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Amino acid substitution patterns between the nonbarophilic Pyrococcus furiosus and its barophilic relative P. abyssi confirm that hydrostatic pressure asymmetry indices reflect the extent to which amino acids are preferred by barophilic archaeal organisms. Substitution patterns in entire protein sequences, shared protein domains defined at fold superfamily level, domains in homologous sequence pairs, and domains of very ancient and very recent origin now provide further clues about the environment that led to the genetic code and diversified life. The pyrococcal proteomes are very similar and share a very early ancestor. Relative amino acid abundance analyses showed that biases in the use of amino acids are due to their shared fold superfamilies. Within these repertoires, only two of the five amino acids that are preferentially barophilic, aspartic acid and arginine, displayed this preference significantly and consistently across structure and in domains appearing in the ancestor. The more primordial asparagine, lysine and threonine displayed a consistent preference for nonbarophily across structure and in the ancestor. Since barophilic preferences are already evident in ancient domains that are at least ~3 billion year old, we conclude that barophily is a very ancient trait that unfolded concurrently with genetic idiosyncrasies in convergence towards a universal code.