There is appreciable data demonstrating that the control of the translation elongation process is a universal mechanism used by the cells to regulate the expression of genes. Translation elongation can be controlled by diverse mechanisms since a substantial number of different factors and events are involved in the process; proposing that more of this regulatory mechanism still unknown. Despite the diversity, the elongation regulatory mechanisms keep two common and essential characteristics: 1) the translated sequence itself plays an important role in the regulatory process; and 2) the inhibition, or delay in the elongation due to a regulated event can lead to the accumulation of the involved translating peptidyl-tRNA. The accumulation of these peptidyl-tRNAs undoubtedly reflects the use of one of several specific regulatory mechanisms designed to modulate expression of a specific gene(s). The objective of OUR WORK is to identify genes subject to translation elongation regulation in several model organisms. Our work will generate methodologies to isolate and identify peptidyl-tRNAs involved in the gene expression under relevant cell growth conditions. Also, it will determine the molecular mechanism(s) responsible for these translational regulation examples. Our long term goal is to produce a gene-expression profiling technology to analyze in vivo other important phenomena related with accumulation of peptidyl-tRNA such as: the action of antibiotic translation inhibitors, codon translation efficiency, coupling translation-protein folding, among others; a complementary technology for other broadly used as microarray and proteomics.
Genes mostly encode functional protein products. Protein synthesis requires two intermediate steps which are tightly controlled and regulate gene expression: transcription and translation. There is appreciable data showing that negative or positive expression of a gene can be regulated by inhibition of translation elongation. Translation elongation inhibition can be achieved by diverse mechanisms since a substantial number of different factors and events are involved in the translation process. In recent years several examples have been identified in which translation elongation inhibition participates in regulating expression of essential genes, such regulated genes have been described in diverse organisms, including genes involved in cell development, phage growth and cell metabolism. It is also known that translation elongation inhibition influences the localized expression of some genes, regulates protein folding induced by chaperons and inhibits cell growth. In our studies, we have shown that it is possible to detect the uncleaved peptidyl-tRNA produced during a regulatory event. It is therefore plausible to assume that all those peptidyl-tRNAs, participating in a regulatory event involving inhibition of translation, have a longer half-life in the cell than those peptidyl-tRNAs involved in normal translation processes. Our proposal is based on the hypothesis that many of the peptidyl-tRNAs that exist or accumulate in a cell at any given moment represent those genes subject to translational regulation under the specific growth conditions examined. The accumulation of these peptidyl-tRNAs undoubtedly reflects the use of one of several specific regulatory mechanisms designed to regulate expression of genes involved in essential processes.
