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Deletion of dop in Mycobacterium smegmatis abolishes pupylation of protein substrates in vivo


Imkamp, F; Rosenberger, T; Striebel, F; Keller, P M; Amstutz, B; Sander, P; Weber-Ban, E (2010). Deletion of dop in Mycobacterium smegmatis abolishes pupylation of protein substrates in vivo. Molecular Microbiology, 75(3):744-754.

Abstract

Proteasome-bearing bacteria make use of a ubiquitin-like modification pathway to target proteins for proteasomal turnover. In a process termed pupylation, proteasomal substrates are covalently modified with the small protein Pup that serves as a degradation signal. Pup is attached to substrate proteins by action of PafA. Prior to its attachment, Pup needs to undergo deamidation at its C-terminal residue, converting glutamine to glutamate. This step is catalyzed in vitro by Dop. In order to characterize Dop activity in vivo, we generated a dop deletion mutant in Mycobacterium smegmatis. In the Deltadop strain, pupylation is severely impaired and the steady-state levels of two known proteasomal substrates are drastically increased. Pupylation can be re-established by complementing the mutant with either DopWt or a Pup variant carrying a glutamate at its ultimate C-terminal position (PupGGE). Our data show that Pup is deamidated by Dop in vivo and that likely Dop alone is responsible for this activity. Furthermore, we demonstrate that a putative N-terminal ATP binding motif is crucial for catalysis, since a single point mutation (E10A) in this motif abolishes Dop activity both in vivo and in vitro.

Proteasome-bearing bacteria make use of a ubiquitin-like modification pathway to target proteins for proteasomal turnover. In a process termed pupylation, proteasomal substrates are covalently modified with the small protein Pup that serves as a degradation signal. Pup is attached to substrate proteins by action of PafA. Prior to its attachment, Pup needs to undergo deamidation at its C-terminal residue, converting glutamine to glutamate. This step is catalyzed in vitro by Dop. In order to characterize Dop activity in vivo, we generated a dop deletion mutant in Mycobacterium smegmatis. In the Deltadop strain, pupylation is severely impaired and the steady-state levels of two known proteasomal substrates are drastically increased. Pupylation can be re-established by complementing the mutant with either DopWt or a Pup variant carrying a glutamate at its ultimate C-terminal position (PupGGE). Our data show that Pup is deamidated by Dop in vivo and that likely Dop alone is responsible for this activity. Furthermore, we demonstrate that a putative N-terminal ATP binding motif is crucial for catalysis, since a single point mutation (E10A) in this motif abolishes Dop activity both in vivo and in vitro.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Medical Microbiology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Language:English
Date:13 January 2010
Deposited On:20 Jan 2010 09:30
Last Modified:05 Apr 2016 13:42
Publisher:Wiley-Blackwell
ISSN:0950-382X
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:10.1111/j.1365-2958.2009.07013.x
PubMed ID:20025664
Permanent URL: http://doi.org/10.5167/uzh-26506

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