Work

Mutational analysis of Escherichia coli GreA protein reveals new functional activity independent of antipause and lethal when overexpressed

Year: 2020

Type: article

Abstract: There is a growing appreciation for the diverse regulatory consequences of the family of proteins that bind to the secondary channel of E. coli RNA polymerase (RNAP), such as GreA, GreB or DksA. Similar binding sites could suggest a competition between them. GreA is characterised to rescue stalled RNAP complexes due to its antipause activity, but also it is involved in transcription fidelity and proofreading. Here, overexpression of GreA is noted to be lethal independent of its antipause activity. A library of random GreA variants has been used to isolate lethality suppressors to assess important residues for GreA functionality and its interaction with the RNA polymerase. Some mutant defects are inferred to be associated with altered binding competition with DksA, while other variants seem to have antipause activity defects that cannot reverse a GreA-sensitive pause site in a fliC::lacZ reporter system. Surprisingly, apparent binding and cleavage defects are found scattered throughout both the coiled-coil and globular domains. Thus, the coiled-coil of GreA is not just a measuring stick ensuring placement of acidic residues precisely at the catalytic centre but also seems to have binding functions. These lethality suppressor mutants may provide valuable tools for future structural and functional studies.

Source: Scientific Reports

DOI: 10.1038/s41598-020-73069-1

Authors: Llorenç Fernández-Coll, Katarzyna Potrykus, Michael Cashel, Carlos Balsalobre

Institutions: National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development, University of Gdańsk, Universitat de Barcelona

Language: English

Topic: Bacterial Genetics and Biotechnology

Subfield: Genetics

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: gold

Estimated APC paid: $1,870