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Characterization of a transport activity for long-chain peptides in barley mesophyll vacuoles


Ramos, M S; Abele, R; Nagy, R; Grotemeyer, M S; Tampé, R; Rentsch, D; Martinoia, E (2011). Characterization of a transport activity for long-chain peptides in barley mesophyll vacuoles. Journal of Experimental Botany, 62(7):2403-2410.

Abstract

The plant vacuole is the largest compartment in a fully expanded plant cell. While only very limited metabolic activity can be observed within the vacuole, the majority of the hydrolytic activities, including proteolytic activities reside in this organelle. Since it is assumed that protein degradation by the proteasome results in the production of peptides with a size of 3-30 amino acids, we were interested to show whether the tonoplast exhibits a transport activity, which could deliver these peptides into the vacuole for final degradation. It is shown here that isolated barley mesophyll vacuoles take up peptides of 9-27 amino acids in a strictly ATP-dependent manner. Uptake is inhibited by vanadate, but not by NH(+)(4), while GTP could partially substitute for ATP. The apparent affinity for the 9 amino acid peptide was 15 μM, suggesting that peptides are efficiently transferred to the vacuole in vivo. Inhibition experiments showed that peptides with a chain length below 10 amino acids did not compete as efficiently as longer peptides for the uptake of the 9 amino acid peptide. Our results suggest that vacuoles contain at least one peptide transporter that belongs to the ABC-type transporters, which efficiently exports long-chain peptides from the cytosol into the vacuole for final degradation.

The plant vacuole is the largest compartment in a fully expanded plant cell. While only very limited metabolic activity can be observed within the vacuole, the majority of the hydrolytic activities, including proteolytic activities reside in this organelle. Since it is assumed that protein degradation by the proteasome results in the production of peptides with a size of 3-30 amino acids, we were interested to show whether the tonoplast exhibits a transport activity, which could deliver these peptides into the vacuole for final degradation. It is shown here that isolated barley mesophyll vacuoles take up peptides of 9-27 amino acids in a strictly ATP-dependent manner. Uptake is inhibited by vanadate, but not by NH(+)(4), while GTP could partially substitute for ATP. The apparent affinity for the 9 amino acid peptide was 15 μM, suggesting that peptides are efficiently transferred to the vacuole in vivo. Inhibition experiments showed that peptides with a chain length below 10 amino acids did not compete as efficiently as longer peptides for the uptake of the 9 amino acid peptide. Our results suggest that vacuoles contain at least one peptide transporter that belongs to the ABC-type transporters, which efficiently exports long-chain peptides from the cytosol into the vacuole for final degradation.

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8 citations in Web of Science®
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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Plant and Microbial Biology
Dewey Decimal Classification:580 Plants (Botany)
Language:English
Date:2011
Deposited On:03 Jan 2012 18:16
Last Modified:05 Apr 2016 15:18
Publisher:Oxford University Press
ISSN:0022-0957
Additional Information:This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Journal of Experimental Botany following peer review. The definitive publisher-authenticated version J Exp Bot. 2011;62(7):2403-10 is available online at: http://dx.doi.org/10.1093/jxb/erq397
Publisher DOI:https://doi.org/10.1093/jxb/erq397
PubMed ID:21282327
Permanent URL: https://doi.org/10.5167/uzh-53835

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