Mycobacterial DnaB helicase intein as oxidative stress sensor

Authors

Marlene Belfort, University at Albany, State University of New York
Hongmin Li, University at Albany, State University of New York
Nilesh K. Banavali, University at Albany, State University of New York
Michael R. Miller, University at Albany, State University of New York
Zhong Li, New York State Department of Health
Christopher W. Lennon, University at Albany, State University of New York
Danielle S. Kelley, University at Albany, State University of New York

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Document Type

Article

Publication Date

2018

DOI

https://doi.org/10.1038/s41467-018-06554-x

Abstract

Inteins are widespread self-splicing protein elements emerging as potential post-translational environmental sensors. Here, we describe two inteins within one protein, the Mycobacterium smegmatis replicative helicase DnaB. These inteins, DnaBi1 and DnaBi2, have homology to inteins in pathogens, splice with vastly varied rates, and are differentially responsive to environmental stressors. Whereas DnaBi1 splicing is reversibly inhibited by oxidative and nitrosative insults, DnaBi2 is not. Using a reporter that measures splicing in a native intein-containing organism and western blotting, we show that H₂O₂ inhibits DnaBi1 splicing in M. smegmatis. Intriguingly, upon oxidation, the catalytic cysteine of DnaBi1 forms an intramolecular disulfide bond. We report a crystal structure of the class 3 DnaBi1 intein at 1.95 Å, supporting our findings and providing insight into this splicing mechanism. We propose that this cysteine toggle allows DnaBi1 to sense stress, pausing replication to maintain genome integrity, and then allowing splicing immediately when permissive conditions return.

Comments

This is the Publisher’s PDF of the following article made available by Nature Communications: Kelley, D.S., Lennon, C.W., Li, Z. et al. Mycobacterial DnaB helicase intein as oxidative stress sensor. Nat Commun 9, 4363 (2018). https://doi.org/10.1038/s41467-018-06554-x

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Recommended Citation

Belfort, Marlene; Li, Hongmin; Banavali, Nilesh K.; Miller, Michael R.; Li, Zhong; Lennon, Christopher W.; and Kelley, Danielle S., "Mycobacterial DnaB helicase intein as oxidative stress sensor" (2018). Biological Sciences Faculty Scholarship. 19.
https://scholarsarchive.library.albany.edu/biology_fac_scholar/19