Does the growth temperature of a prokaryote influence the purine content of its mRNAs?

• Published in: Gene Vol. 497; no. 1; pp. 83 - 89
• Main Authors: Mahale, Kiran Narasinha, Kempraj, Vivek, Dasgupta, Debjani
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10.04.2012
• Subjects: Base Composition; Chargaff; Databases, Nucleic Acid; DNA; GC; genome; hydrogen bonding; messenger RNA; nucleotide sequences; nucleotides; Optimum growth temperature; prokaryotic cells; Prokaryotic Cells - physiology; Purine loading; Purines; RNA, Messenger - chemistry; surveys; Szybalski; Temperature; thermal stability; Thermophiles; Szybalski; Chargaff; TT dimer; Thermophiles; R-loading; Purine loading; R; YY dimer; Optimum growth temperature; Y-loading; Y; GC; OGT
• ISSN: 0378-1119; 1879-0038
• DOI: 10.1016/j.gene.2012.01.040

The formation and breaking of hydrogen bonds between nucleic acid bases are dependent on temperature. The high G+C content of organisms was surmised to be an adaptation for high temperature survival because of the thermal stability of G:C pairs. However, a survey of genomic GC% and optimum growth temperature (OGT) of several prokaryotes revoked any direct relation between them. Significantly high purine (R=A or G) content in mRNAs is also seen as a selective response for survival among thermophiles. Nevertheless, the biological relevance of thermophiles loading their unstable mRNAs with excess purines (purine-loading or R-loading) is not persuasive. Here, we analysed the mRNA sequences from the genomes of 168 prokaryotes (as obtained from NCBI Genome database) with their OGTs ranging from −5°C to 100°C to verify the relation between R-loading and OGT. Our analysis fails to demonstrate any correlation between R-loading of the mRNA pool and OGT of a prokaryote. The percentage of purine-loaded mRNAs in prokaryotes is found to be in a rough negative correlation with the genomic GC% (r2=0.655, slope=−1.478, P<000.1). We conclude that genomic GC% and bias against certain combinations of nucleotides drive the mRNA-synonymous (sense) strands of DNA towards variations in R-loading. ► An updated analysis of 168 prokaryotic mRNA pools for purine-loading. ► No correlation between purine-loading and OGT of prokaryotes. ► Dataset of 53 mesophiles (OGT=37°C) show nearly all patterns of purine-loading. ► Genomic GC% in a negative correlation with the percentage of purine-loaded mRNAs. ► GC%, YY dimers and G-rich tracts drive mRNAs towards variations in R-loading.