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The Allosteric Regulatory Mechanism of the E.Coli Metni Methionine ABC Transporter

Yang, Janet G. and Rees, Douglas C. (2016) The Allosteric Regulatory Mechanism of the E.Coli Metni Methionine ABC Transporter. Biophysical Journal, 110 (3). 140A. ISSN 0006-3495. doi:10.1016/j.bpj.2015.11.796.

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The MetNI methionine importer of Escherichia coli, an ATP Binding Cassette (ABC) transporter, uses the energy of ATP binding and hydrolysis to catalyze the high affinity uptake of D- and L-methionine. Early in vivo studies showed that the uptake of external methionine is repressed by the level of the internal methionine pool, a phenomenon termed transinhibition. Our understanding of MetNI mechanism has thus far been limited to a series of crystal structures in an inward facing conformation. To understand the molecular mechanism of transinhibition, we studied the kinetics of ATP hydrolysis using detergent-solubilized MetNI. We find that transinhibition is due to noncompetitive inhibition by L-methionine, much like a negative feedback loop. Thermodynamic analyses revealed two allosteric methionine binding sites per transporter. This quantitative analysis of transinhibition, the first to our knowledge for a structurally defined transporter, builds upon the previously proposed structurally based model for regulation. This mechanism of regulation at the transporter activity level could be applicable to not only ABC transporters but other types of membrane transporters as well.

Item Type:Article
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Rees, Douglas C.0000-0003-4073-1185
Additional Information:© 2016 Biophysical Society. Published by Elsevier Inc.
Issue or Number:3
Record Number:CaltechAUTHORS:20160606-075431894
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Official Citation:Janet G. Yang, Douglas C. Rees, The Allosteric Regulatory Mechanism of the E.Coli Metni Methionine ABC Transporter, Biophysical Journal, Volume 110, Issue 3, Supplement 1, 16 February 2016, Page 140a, ISSN 0006-3495, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67670
Deposited By: Tony Diaz
Deposited On:06 Jun 2016 16:40
Last Modified:11 Nov 2021 03:52

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