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Albany 2019: 20th Conversation - Abstracts

category image Albany 2019
Conversation 20
June 11-15 2019
Adenine Press (2019)

RNA helicase activity of E. coli HflX is instrumental in rescuing heat-inactivated 23S ribosomal RNA.

A recent study has revealed that the ribosome-associated GTPase HflX acts as an anti-association factor upon binding to the 50S subunit during heat stress. Although HflX is recognized as a GTPase, several studies have shown that E.coli HflX is capable of hydrolyzing ATP as well and its N-terminal domain 1 has recently been characterized as the ATPase domain. However, the functional role of its ATPase activity remains unknown. Here, using biochemical assays and atomic force microscopy, we demonstrate for the first time, that E. coli HflX possesses ATP-dependent RNA helicase activity and is capable of unwinding large subunit ribosomal RNA. A cryo-EM structure of the 50S-HflX complex in the presence of ATP and GTP (non-hydrolysable analogs) hinted at the mode of its action as an RNA helicase, where a helical domain has a determinant role in RNA unwinding. We further show that, while heat-stress results in inactivation of the ribosome, HflX can restore heat-damaged ribosomes and, consequently, ameliorate cell survivability.

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References
    Dey S, Biswas C, Sengupta J. The universally conserved GTPase HflX is an RNA helicase that restores heat-damaged Escherichia coli ribosomes (2018). J Cell Biol. 217(7),2519-2529.

    Coatham ML, Brandon HE, Fischer JJ, Schümmer T, Wieden HJ. The conserved GTPase HflX is a ribosome splitting factor that binds to the E-site of the bacterial ribosome (2016). Nucleic Acids Res. 44(4), 1952-61.

    Zhang Y, Mandava CS, Cao W, Li X, Zhang D, Li N, Zhang Y, Zhang X, Qin Y, Mi K, Lei J, Sanyal S, Gao N (2015). HflX is a ribosome-splitting factor rescuing stalled ribosomes under stress conditions. Nat Struct Mol Biol. 22(11), 906-13.

Sandip Dey
Krishnamoorthi Srinivasan
Jayati Sengupta

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A few years ago Jayati was a post-doctoral fellow under Prof. Joachim Frank. Now she has established her own Cryo-EM Lab in Kolkata, India.

Structural Biology & Bio-Informatics
CSIR-Indian Institute of Chemical Biology
4, Raja S.C. Mullick Road
Kolkata-700 032, India

Phone: +91 33 2499 5764
Email: jayati@iicb.res.in