Eukaryotic Cell
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Mason, D. L.
Right arrow Articles by Michaelis, S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Mason, D. L.
Right arrow Articles by Michaelis, S.
Eukaryotic Cell, June 2003, p. 588-598, Vol. 2, No. 3
1535-9778/03/$08.00+0     DOI: 10.1128/EC.2.3.588-598.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

A Region within a Lumenal Loop of Saccharomyces cerevisiae Ycf1p Directs Proteolytic Processing and Substrate Specificity

Deborah L. Mason, Monica P. Mallampalli, Gregory Huyer, and Susan Michaelis*

Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205

Received 3 February 2003/ Accepted 14 February 2003

Ycf1p, a member of the yeast multidrug resistance-associated protein (MRP) subfamily of ATP-binding cassette proteins, is a vacuolar membrane transporter that confers resistance to a variety of toxic substances such as cadmium and arsenite. Ycf1p undergoes a PEP4-dependent processing event to yield N- and C-terminal cleavage products that remain associated with one another. In the present study, we sought to determine whether proteolytic cleavage is required for Ycf1p activity. We have identified a unique region within lumenal loop 6 of Ycf1p, designated the loop 6 insertion (L6ins), which appears to be necessary and sufficient for proteolytic cleavage, since L6ins can promote processing when moved to new locations in Ycf1p or into a related transporter, Bpt1p. Surprisingly, mutational results indicate that proteolytic processing is not essential for Ycf1p transport activity. Instead, the L6ins appears to regulate substrate specificity of Ycf1p, since certain mutations in this region lower cellular cadmium resistance with a concomitant gain in arsenite resistance. Although some of these L6ins mutations block processing, there is no correlation between processing and substrate specificity. The activity profiles of the Ycf1p L6ins mutants are dramatically affected by the strain background in which they are expressed, raising the possibility that another cellular component may functionally impact Ycf1p activity. A candidate component may be a new full-length MRP-type transporter (NFT1), reported in the Saccharomyces Genome Database as two adjacent open reading frames, YKR103w and YKR104w, but which we show here is present in most Saccharomyces strains as a single open reading frame.

* Corresponding author. Mailing address: Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205. Phone: (410) 955-7274. Fax: (410) 955-4129. E-mail: michaelis{at}jhmi.edu.

Eukaryotic Cell, June 2003, p. 588-598, Vol. 2, No. 3
1535-9778/03/$08.00+0     DOI: 10.1128/EC.2.3.588-598.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:



HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Appl. Environ. Microbiol. Infect. Immun. J. Bacteriol.
Mol. Cell Biol. Microbiol. Mol. Biol. Rev. ALL ASM JOURNALS
Copyright © 2003 by the American Society for Microbiology.