Ribosomes of all organisms are the main factor taking part in the translation. Ribosomes realize two main functions - messenger RNA decoding and peptide bridge formation. These two activities are located in the two big ribonucleoprotein parts of unequial sizes – ribosomal subunits. Every subunit contains one or more ribosomal RNA (rRNA) and many ribosomal proteins (r-proteins). Small subunit (30S in bacteria and 40S in eukaryotes) has decoding function, whereas bid subunit (50S in bacteria and 60S in eukaryotes) catalyses peptide bridge formation.

The ribosomes synthesis reveals the high degree of evolutional conservatism. In all organisms mature rRNA forms as a result of post-transcriptional processing (“maturing”) from rRNA predecessor (pre-rRNA). The key steps of ribosomes synthesis are: pre-rRNA transcription, covalent modification of their regions, processing of the pre-rRNA to the mature rRNA and assembling rRNA with ribosomal proteins. Eukaryotes have additional stage which consists of import of r-proteins from cytoplasm to nucleus and export of ribosomal subunits from nucleolus through the nucleoplasm and nuclear pore complex to the cytoplasm.

Compact nature of RNA structure being revealed in ribosomal subunits has the problem for RNA synthesis in the whole. In order to provide the access to the processing, modification and assembling, the factors taking part in the biosynthesis (proteins and small RNA) should appear in the strong time consecution during ribosome synthesis. The final rRNA folding has to be hold right up to the last pathway stage, supporting key regions of rRNA in the relatively friable state. After these stages rRNA should be folded in the mature structure.

During RYBOSYS project organized at the 6-th framework programme we have developed several models of rRNA processing. These models have been used for prediction of system properties of rRNA synthesis and analysis of specific experimental data. More information about research consortium RYBOSYS you could find HERE.

AIM OF MODELING STUDIES IN THE PROJECT: To create a formal mathematical representation of the pathway of pre-rRNA processing and degradation, which will describe pre-rRNA and rRNA metabolism in yeast quantitatively.

MAIN RESULTS

	Result 1. Pathway of pre-rRNA processing and degradation have been reconstructed.
	Result 2. Kinetic model of pre-rRNA processing and degradation has been developed and validated against in vitro and in vivo data.