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Sharma A, Dubey V, Sharma R, Devnath K, Gupta VK, Akhter J, Bhando T, Verma A, Ambatipudi K, Sarkar M, Pathania R. The unusual glycine-rich C terminus of the Acinetobacter baumannii RNA chaperone Hfq plays an important role in bacterial physiology. J Biol Chem 2018; 293:13377-13388. [PMID: 30002121 DOI: 10.1074/jbc.ra118.002921] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 06/28/2018] [Indexed: 11/06/2022] Open
Abstract
Acinetobacter baumannii is a Gram-negative nosocomial pathogen that causes soft tissue infections in patients who spend a long time in intensive care units. This recalcitrant bacterium is very well known for developing rapid drug resistance, which is a combined outcome of its natural competence and mobile genetic elements. Successful efforts to treat these infections would be aided by additional information on the physiology of A. baumannii Toward that end, we recently reported on a small RNA (sRNA), AbsR25, in this bacterium that regulates the genes of several efflux pumps. Because sRNAs often require the RNA chaperone Hfq for assistance in binding to their cognate mRNA targets, we identified and characterized this protein in A. baumannii The homolog in A. baumannii is a large protein with an extended C terminus unlike Hfqs in other Gram-negative pathogens. The extension has a compositional bias toward glycine and, to a lower extent, phenylalanine and glutamine, suggestive of an intrinsically disordered region. We studied the importance of this glycine-rich tail using truncated versions of Hfq in biophysical assays and complementation of an hfq deletion mutant, finding that the tail was necessary for high-affinity RNA binding. Further tests implicate Hfq in important cellular processes of A. baumannii like metabolism, drug resistance, stress tolerance, and virulence. Our findings underline the importance of the glycine-rich C terminus in RNA binding, ribo-regulation, and auto-regulation of Hfq, demonstrating this hitherto overlooked protein motif to be an indispensable part of the A. baumannii Hfq.
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Affiliation(s)
- Atin Sharma
- From the Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India and
| | - Vineet Dubey
- From the Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India and
| | - Rajnikant Sharma
- From the Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India and
| | - Kuldip Devnath
- From the Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India and
| | - Vivek Kumar Gupta
- From the Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India and
| | - Jawed Akhter
- From the Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India and
| | - Timsy Bhando
- From the Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India and
| | - Aparna Verma
- From the Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India and
| | - Kiran Ambatipudi
- From the Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India and
| | - Mihir Sarkar
- the Division of Physiology and Climatology, ICAR-Indian Veterinary Research Institute, Izatnagar-Bareilly (UP) 243122, India
| | - Ranjana Pathania
- From the Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India and
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