Mycobacterial transcript cleavage factor Gre, exhibits chaperone-like activity

Joseph, Abyson and Nagaraja, Valakunja and Natesh, Ramanathan (2019) Mycobacterial transcript cleavage factor Gre, exhibits chaperone-like activity. In: BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS, 1867 (9). pp. 757-764.

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Abstract

Gre factors reactivate stalled elongation complexes by enhancing the intrinsic transcript cleavage activity of RNA polymerase. Previous work by us has shown that unlike in Escherichia coli (E.coli), Mycobacterium tuberculosis Gre factor is essential for its survival. Apart from their role in transcription regulation Gre factors have been implicated in stress response. A recent study has shown the role of E.coli GreA as a cellular chaperone, which inhibits aggregation of substrate proteins under heat stress condition. Moreover it was shown that GreA enables E.coli to survive heat shock and oxidative stress. In the current work, we have characterized the moonlighting chaperone activity and its plausible mechanism in Mycobacterium smegmatis Gre (MsGre) factor. We show here that MsGre prevents heat-induced aggregation of the substrate protein and also protects enzymatic activity. Interestingly Gre factor exists as a dimer in solution and does not undergo heat induced oligomerization. From the 8-anilino-1-naphthalene sulfonate (ANS) binding studies MsGre was shown to expose hydrophobic surface upon heat stress that would allow binding to unfolded or partially folded substrate protein. From Circular Dichroism (CD) studies, we also show that MsGre has a stable secondary structure under thermal stress. We propose that the presence of C-terminal FKBP-like fold in MsGre factor that might contribute to its chaperone-like function.

Item Type:	Journal Article
Publication:	BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS
Publisher:	ELSEVIER
Additional Information:	copyright for this article belongs to ELSEVIER
Department/Centre:	Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited:	19 Sep 2019 07:38
Last Modified:	19 Sep 2019 07:38
URI:	http://eprints.iisc.ac.in/id/eprint/63510

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