PNNL

Abstract

The modest correlation between mRNA expression and protein abundance in large scale datasets is explained in part by experimental challenges, such as technological limitations, and in part by fundamental biological factors in the transcription and translation processes. Among various factors affecting the mRNA-protein correlation, the roles of biological factors related to translation are poorly understood. In this study, using experimental mRNA expression and protein abundance data collected from Desulfovibrio vulgaris by DNA microarray and LC-MS/MS proteomic analysis, we quantitatively examined the effects of several translational-efficiency-related sequence features on mRNA-protein correlation. Three classes of sequence features were investigated according to different translational stages: i) initiation: Shine-Dalgarno sequences, start codon identity and start codon context; ii) elongation: codon usage and amino acid usage; and iii) termination: stop codon identity and stop codon context. Surprisingly, although it is widely accepted that translation initiation is a rate-limiting step for translation, our results showed that the mRNA-protein correlation was affected the most by the features at elongation stages, codon usage and amino acid composition (7.4-12.6% and 5.3-9.3% of the total variation of mRNA-protein correlation, respectively), followed by stop codon context and the Shine-Dalgarno sequence (2.5-4.2% and 2.3%, respectively). Taken together, all sequence features contributed to 18.4-21.8% of the total variation of mRNAprotein correlation. As the first comprehensive quantitative analysis of the mRNA-protein correlation in bacterial D. vulgaris, our results suggest that the traditional view of the relative importance of various sequence features in prokaryotic protein translation might be questionable.