TY - JOUR
T1 - Multiple Targeting Modules on Peroxisomal Proteins Are Not Redundant
T2 - Discrete Functions of Targeting Signals within Pmp47 and Pex8p
AU - Wang, Xiaodong
AU - McMahon, Moira A.
AU - Shelton, Shary N.
AU - Nampaisansuk, Mongkol
AU - Ballard, Johnathan L.
AU - Goodman, Joel M.
PY - 2004/4
Y1 - 2004/4
N2 - Several peroxisomal proteins have two nonoverlapping targeting signals. These signals have been termed "redundant" because targeting can still occur with only one signal. We now report that separate targeting motifs within both Pmp47 and Pex8 provide complementary function. Pmp47 is an ATP translocator that contains six transmembrane domains (TMDs). We had previously shown that the TMD2 region (termed TMD2R, consisting of TMD2 and a short adjacent segment of cytosolic loop) was required for targeting to proliferated peroxisomes in Saccharomyces cerevisiae. We now report that the analogous TMD4R, which cannot target to proliferated peroxisomes, targets at least as well, or much better (depending on strain and growth conditions) in cells containing only basal (i.e., nonproliferated) peroxisomes. These data suggest differences in the targeting pathway among peroxisome populations. Pex8p, a peripheral protein facing the matrix, contains a typical carboxy terminal targeting sequence (PTS1) that has been shown to be nonessential for targeting, indicating the existence of a second targeting domain (not yet defined in S. cerevisiae); thus, its function was unknown. We show that targeting to basal peroxisomes, but not to proliferated peroxisomes, is more efficient with the PTS1 than without it. Our results indicate that multiple targeting signals within peroxisomal proteins extend coverage among heterogeneous populations of peroxisomes and increase efficiency of targeting in some metabolic states.
AB - Several peroxisomal proteins have two nonoverlapping targeting signals. These signals have been termed "redundant" because targeting can still occur with only one signal. We now report that separate targeting motifs within both Pmp47 and Pex8 provide complementary function. Pmp47 is an ATP translocator that contains six transmembrane domains (TMDs). We had previously shown that the TMD2 region (termed TMD2R, consisting of TMD2 and a short adjacent segment of cytosolic loop) was required for targeting to proliferated peroxisomes in Saccharomyces cerevisiae. We now report that the analogous TMD4R, which cannot target to proliferated peroxisomes, targets at least as well, or much better (depending on strain and growth conditions) in cells containing only basal (i.e., nonproliferated) peroxisomes. These data suggest differences in the targeting pathway among peroxisome populations. Pex8p, a peripheral protein facing the matrix, contains a typical carboxy terminal targeting sequence (PTS1) that has been shown to be nonessential for targeting, indicating the existence of a second targeting domain (not yet defined in S. cerevisiae); thus, its function was unknown. We show that targeting to basal peroxisomes, but not to proliferated peroxisomes, is more efficient with the PTS1 than without it. Our results indicate that multiple targeting signals within peroxisomal proteins extend coverage among heterogeneous populations of peroxisomes and increase efficiency of targeting in some metabolic states.
UR - http://www.scopus.com/inward/record.url?scp=1642423544&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=1642423544&partnerID=8YFLogxK
U2 - 10.1091/mbc.E03-11-0810
DO - 10.1091/mbc.E03-11-0810
M3 - Article
C2 - 14742703
AN - SCOPUS:1642423544
SN - 1059-1524
VL - 15
SP - 1702
EP - 1710
JO - Molecular biology of the cell
JF - Molecular biology of the cell
IS - 4
ER -