Pathway of ATP utilization and duplex rRNA unwinding by the DEAD-box helicase, DbpA.
DEAD-box RNA helicase proteins use the energy of ATP hydrolysis to drive the unwinding of duplex RNA. However, the mechanism that couples ATP utilization to duplex RNA unwinding is unknown. We measured ATP utilization and duplex RNA unwinding by DbpA, a non-processive bacterial DEAD-box RNA helicase specifically activated by the peptidyl transferase center (PTC) of 23S rRNA. Consumption of a single ATP molecule is sufficient to unwind and displace an 8 base pair rRNA strand annealed to a 32 base pair PTC-RNA "mother strand" fragment. Strand displacement occurs after ATP binding and hydrolysis but before P(i) product release. P(i) release weakens binding to rRNA, thereby facilitating the release of the unwound rRNA mother strand and the recycling of DbpA for additional rounds of unwinding. This work explains how ATPase activity of DEAD-box helicases is linked to RNA unwinding.
Henn
Arnon
A
Department of Molecular Biophysics & Biochemistry, 260 Whitney Avenue, Yale University, New Haven, CT 06520, USA.
Cao
Wenxiang
W
Licciardello
Nicholas
N
Heitkamp
Sara E
SE
Hackney
David D
DD
De La Cruz
Enrique M
EM
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D053487:DEAD-box RNA Helicases / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D006868:Hydrolysis; D009691:Nucleic Acid Denaturation; D012335:RNA, Ribosomal / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism
D029968:Escherichia coli Proteins; D012335:RNA, Ribosomal; D011994:Recombinant Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; C065908:dbpA protein, E coli; D053487:DEAD-box RNA Helicases