HflX is a ribosome-splitting factor rescuing stalled ribosomes under stress conditions.

Yanqing Zhang, Chandra Sekhar Mandava, Wei Cao, Xiaojing Li, Dejiu Zhang, Ningning Li, Yixiao Zhang, Xiaoxiao Zhang, Yan Qin, Kaixia Mi, Jianlin Lei, Suparna Sanyal, Ning Gao

Nature structural & molecular biology 2015 Nov

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Adverse cellular conditions often lead to nonproductive translational stalling and arrest of ribosomes on mRNAs. Here, we used fast kinetics and cryo-EM to characterize Escherichia coli HflX, a GTPase with unknown function. Our data reveal that HflX is a heat shock-induced ribosome-splitting factor capable of dissociating vacant as well as mRNA-associated ribosomes with deacylated tRNA in the peptidyl site. Structural data demonstrate that the N-terminal effector domain of HflX binds to the peptidyl transferase center in a strikingly similar manner as that of the class I release factors and induces dramatic conformational changes in central intersubunit bridges, thus promoting subunit dissociation. Accordingly, loss of HflX results in an increase in stalled ribosomes upon heat shock. These results suggest a primary role of HflX in rescuing translationally arrested ribosomes under stress conditions.

Citation

Yanqing Zhang, Chandra Sekhar Mandava, Wei Cao, Xiaojing Li, Dejiu Zhang, Ningning Li, Yixiao Zhang, Xiaoxiao Zhang, Yan Qin, Kaixia Mi, Jianlin Lei, Suparna Sanyal, Ning Gao. HflX is a ribosome-splitting factor rescuing stalled ribosomes under stress conditions. Nature structural & molecular biology. 2015 Nov;22(11):906-13