A dominant negative mutant of the E. coli RNA helicase DbpA blocks assembly of the 50S ribosomal subunit.

ABSTRACT: Escherichia coli DbpA is an ATP-dependent RNA helicase with specificity for hairpin 92 of 23S ribosomal RNA, an important part of the peptidyl transferase center. The R331A active site mutant of DbpA confers a dominant slow growth and cold sensitive phenotype when overexpressed in E. coli containing endogenous DbpA. Ribosome profiles from cells overexpressing DbpA R331A display increased levels of 50S and 30S subunits and decreased levels 70S ribosomes. Profiles run at low Mg(2+) exhibit fewer 50S subunits and accumulate a 45S particle that contains incompletely processed and undermodified 23S rRNA in addition to reduced levels of several ribosomal proteins that bind late in the assembly pathway. Unlike mature 50S subunits, these 45S particles can stimulate the ATPase activity of DbpA, ind

SUBMITTER: Sharpe Elles LM 

PROVIDER: S-EPMC2770675 | biostudies-literature | 2009 Oct

REPOSITORIES: biostudies-literature