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

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.

Mutation of the arginine finger in the active site of Escherichia coli DbpA abolishes ATPase and helicase activity and confers a dominant slow growth phenotype.

Escherichia coli DEAD-box protein A (DbpA) is an ATP-dependent RNA helicase with specificity for 23S ribosomal RNA. Although DbpA has been extensively characterized biochemically, its biological function remains unknown. Previous work has shown that a DbpA deletion strain is viable with little or no effect on growth rate.