TY - JOUR
T1 - Adaptive role of increase frequency of polypurine tracts in mRNA sequences of thermophilic prokaryotes
AU - Paz, Arnon
AU - Mester, David
AU - Baca, Ivan
AU - Nevo, Eviatar
AU - Korol, Abraham
PY - 2004/3/2
Y1 - 2004/3/2
N2 - The mechanism of an organism's adaptation to high temperatures has been investigated intensively in recent years. It was suggested that the macromolecules of thermophilic microorganisms (especially proteins) have structural features that enhance their thermostability. We compared mRNA sequences of 72 fully sequenced prokaryotic proteomes (14 thermophilic and 58 mesophilic species). Although the differences between the percentage of adenine plus guanine content of whole mRNAs of different prokaryotic species are much lower than those of guanine plus cytosine content, the thermophile purine-pyrimidine (R/Y) ratio within their mRNAs is significantly higher than that of the mesophiles. The first and third codon positions of both thermophiles and mesophiles are purine-biased, with the bias more pronounced by the thermophiles. Thermophile mRNAs that display the highest R/Y ratio (1.43-1.69) are those of the ribosomal proteins, histone-like proteins, DNA-dependent RNA polymerase subunits, and heat-shock proteins. Within mesophilic prokaryotes and five eukaryotic species, the R/Y ratio of the mRNAs of heat-shock proteins is higher than their average over coding part of the genome. Polypurine tracts (R)n (with n ≥ 5) are much more abundant within the thermophile mRNAs compared with mesophiles. Between two sequential pure-purinic codons of thermophile mRNAs, there is a rather strong tendency for the occurrence of adenine but not guanine tracts. The data suggest that mixed adenine-guanine and polyadenine tracts in mRNAs increase the thermostability beyond the contribution of amino acids encoded by purine tracts, which highlights the importance of ecological stress in the evolution of genome architecture.
AB - The mechanism of an organism's adaptation to high temperatures has been investigated intensively in recent years. It was suggested that the macromolecules of thermophilic microorganisms (especially proteins) have structural features that enhance their thermostability. We compared mRNA sequences of 72 fully sequenced prokaryotic proteomes (14 thermophilic and 58 mesophilic species). Although the differences between the percentage of adenine plus guanine content of whole mRNAs of different prokaryotic species are much lower than those of guanine plus cytosine content, the thermophile purine-pyrimidine (R/Y) ratio within their mRNAs is significantly higher than that of the mesophiles. The first and third codon positions of both thermophiles and mesophiles are purine-biased, with the bias more pronounced by the thermophiles. Thermophile mRNAs that display the highest R/Y ratio (1.43-1.69) are those of the ribosomal proteins, histone-like proteins, DNA-dependent RNA polymerase subunits, and heat-shock proteins. Within mesophilic prokaryotes and five eukaryotic species, the R/Y ratio of the mRNAs of heat-shock proteins is higher than their average over coding part of the genome. Polypurine tracts (R)n (with n ≥ 5) are much more abundant within the thermophile mRNAs compared with mesophiles. Between two sequential pure-purinic codons of thermophile mRNAs, there is a rather strong tendency for the occurrence of adenine but not guanine tracts. The data suggest that mixed adenine-guanine and polyadenine tracts in mRNAs increase the thermostability beyond the contribution of amino acids encoded by purine tracts, which highlights the importance of ecological stress in the evolution of genome architecture.
UR - http://www.scopus.com/inward/record.url?scp=1542297746&partnerID=8YFLogxK
U2 - 10.1073/pnas.0308594100
DO - 10.1073/pnas.0308594100
M3 - Article
C2 - 14973185
AN - SCOPUS:1542297746
SN - 0027-8424
VL - 101
SP - 2951
EP - 2956
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 9
ER -