Toward the characterization of the ATP-binding cassette protein RhaT in Rhizobium leguminosarum

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Date
2019-11
Authors
Kim, Derek Dohyun
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Abstract

ATP-binding cassette (ABC) transporters are found throughout all domains of life. Sugar importers are often categorized under the Carbohydrate Uptake Transporter (CUT) system. This classification system is based on the structure of the ABC, in which CUT1 ABCs are comprised of a dimer of two peptides and CUT2s are believed to consist of a single protein. A novel ABC transporter interaction was previously discovered in Rhizobium leguminosarum. The transport activity of the L-rhamnose importer was found to be dependent on an interaction between the sugar kinase (RhaK) and a CUT2 ABC protein (RhaT). In this work, a partial rhaT deletion mutant was found to retain the ability to grow on rhamnose as a sole carbon source, despite missing a substantial portion of its internal region. Through in silico approaches, this partial deletion was characterized and two rhaT truncation mutants were designed to truncate a CUT2 ABC to resemble a CUT1. Although transport rates were greatly reduced, these truncation mutants were able to preserve growth, supporting the feasibility of converting a CUT2 transporter to CUT1. In addition, rhaT deletions were unable to be complemented by rhaT as an independent gene in trans. Complementation of this gene using a multigene transcript was found as a potential workaround to complement this membrane protein. These findings will likely help steer towards characterizing RhaT in the context of its interaction with the kinase RhaK.

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ABC transporter, Rhizobium, Microbiology, Carbohydrate Uptake Transporter, Rhamnose
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