tailieunhanh - Báo cáo khoa học: Ribosome assembly in Escherichia coli strains lacking the RNA helicase DeaD⁄CsdA or DbpA

Ribosome subunit assembly in bacteria is a fast and efficient process. Among the nonribosomal proteins involved in ribosome biogenesis are RNA helicases. We describe ribosome biogenesis inEscherichia colistrains lacking RNA helicase DeaD (CsdA) or DbpA. | ễFEBS Journal Ribosome assembly in Escherichia coli strains lacking the RNA helicase DeaD CsdA or DbpA Lauri Peil Kai Virumae and Jaanus Remme Institute of Molecular and CellBiology University of Tartu Estonia Keywords 23S rRNA DbpA DeaD CsdA ribosome assembly rRNA processing Correspondence J. Remme Riia 23 51010 Tartu Estonia Fax 372 742 0286 Tel 372 737 5031 E-mail jremme@ Received 26 February 2008 revised 22 May 2008 accepted 27 May 2008 doi Ribosome subunit assembly in bacteria is a fast and efficient process. Among the nonribosomal proteins involved in ribosome biogenesis are RNA helicases. We describe ribosome biogenesis in Escherichia coli strains lacking RNA helicase DeaD CsdA or DbpA. Ribosome large subunit assembly intermediate particles 40S accumulate at 25 C and at 37 C in the absence of DeaD but not without DbpA. 23S rRNA is incompletely processed in the 40S and 50S particles of the DeaD strain. Pulse labeling showed that the 40S particles are converted nearly completely into functional ribosomes. The rate of large ribosomal subunit assembly was reduced about four times in DeaD-deficient cells. Functional activity tests of the ribosomal particles demonstrated that the final step of 50S assembly the activation step was affected when DeaD was not present. The results are compatible with the model that predicts multiple DeaD-catalyzed structural transitions of the ribosome large subunit assembly. The ribosome is a large complex and dynamic ribonucleoprotein particle consisting of a large and a small subunit. In Escherichia coli the large 50S subunit contains two rRNA molecules 23S and 5S rRNA and 33 ribosomal proteins r-proteins whereas the small 30S subunit contains one rRNA molecule 16S rRNA and 21 r-proteins 1 . Assembly of ribosomes is a complex and highly coordinated process which is initiated during rRNA transcription 2 and involves processing modification and folding of rRNA and r-proteins as well as their .