Thioredoxin-related Protein 32 is an arsenite-regulated Thiol Reductase of the proteasome 19 S particle
Authors: David Ron
Chong-Feng Xu
Nevan J Krogan
Ariel Stanhill
Thomas A Neubert
R Luke Wiseman
King-Tung Chin
Assen Roguev
Cole M Haynes
Journal: Journal of Biological Chemistry (2009)
Discipline: BIOLOGY & BIOCHEMISTRY
Keywords: Proteasome; TRP32; As(III); Oxidative stress; Thiol reductase
Affiliations: Kimmel Center for Biology and Medicine of the Skirball Institute , New York University School of Medicine, New York, New York 10016, USA.

Abstract:  Perturbation of the cytoplasmic protein folding environment by exposure to oxidative stress-inducing As(III)-containing compounds challenges the ubiquitin-proteasome system. Here we report on mass spectrometric analysis of As(III)-induced changes in the proteasome's composition in samples prepared by stable isotope labeling with amino acids in cell culture, using mammalian cells in which TRP32 (thioredoxin-related protein of 32 kDa; also referred to as TXNL1) was identified as a novel subunit of the 26 S proteasome. Quantitative genetic interaction mapping, using the epistatic miniarray profiling approach, identified a functional connection between TRP32 and the proteasome. Deletion of txl1, the Schizosaccharomyces pombe homolog of TRP32, results in a slow growth phenotype when combined with deletion of cut8, a gene required for normal proteasome localization. Deletion analysis in vivo, chemical cross-linking, and manipulation of the ATP concentration in vitro during proteasome immunopurification revealed that the C-terminal domain of mammalian TRP32 binds the 19 S regulatory particle in proximity to the proteasome substrate binding site. Thiol modification with polyethylene glycol-maleimide showed disulfide bond formation at the active site of TRP32 in cells exposed to As(III). Pulse-chase labeling showed that TRP32 is a stable protein whose half-life of &gt;6 h is surprisingly reduced to 1 h upon exposure of cells to As(III). These findings reveal a previously undescribed thiol reductase at the proteasome's regulatory particle. 

Retracted: No

PubPeer comments:
 Figure 2A u2013 Much more similar than expected. Could authors check it please? ![file] , 
 18-May-20 Thanks for bringing this to my attention. There is little doubt, that due to an error, the same image was uploaded twice, once labeled as a immunoblot of PSMD7 and once as PSMA1. As both PSMD7 and PSMA1 aremarkers of the 26S proteasome the confusion arising from this unfortunate error should be minimal and its impact on the conclusion that a fraction of Trp32 co-migrates on the gradient with proteasomes is likewise minimal. I shall try to locate the original records relating to the manuscript and if possible correct the error. David Ron University of Cambridge , 
 I also wanted to thank you for pointing out this error in this manuscript. I have located the original blots, and indeed, the PSMA1 image shown in the original manuscript was a duplicate of the PSMD7 image. I apologize for this mistake which occurred during figure production. Below please find a revised panel 2C where the correct PSMA1 blot is shown. As indicated in the text and manuscript, this corrected panel is completely consistent with other data in our manuscript showing that TRP32 localizes to the 26S proteasome. To correct this in the scientific record of our manuscript, I am also emailing the Journal of Biological Chemistry with both the revised figure and the raw data to include in a correction to our manuscript. Again, I apologize for this mistake, and I appreciate your pointing it out so that we may correct this issue ![file] , 
 2020 correction. https: www.jbc.org content 295 27 9267.short In Fig. 2C, the image of the PSMD7 immunoblot was inadvertently duplicated and presented as both the PSMD7 and PSMA1 immunoblots. This error has now been corrected using the original source data files. This correction does not affect the results or conclusions of this work. ,