Poster: Organelle biogenesis
Abs #
640: Subcellular localization and molecular targeting signals for five putative Arabidopsis peroxin 11 homologs
|
|
Presenter: |
Lingard, Matthew J., matthew.lingard@asu.edu |
Authors | Trelease, Richard N. (A) Lingard, Matthew J. (A) | | Affiliations: |
(A): Arizona State University
|
|
|
Plant and other eukaryotic cells possess a basal population of peroxisomes that participate in varied housekeeping and specialized functions; however, internal/external cues may stimulate peroxisomal proliferation. Proteins required for peroxisomal biogenesis are termed peroxins (Pex). S. cerevisiae Pex11 family (Pex11 & 28-32) and mammalian forms (Pex11α,β, & γ), participate in peroxisomal proliferation. The current study was undertaken to identify and characterize such proteins in plants. Five putative Arabidopsis Pex11 homologs (AtPex11a,b,c,d, & e) were identified in protein databases. Analyses of primary protein structure indicate that each form possesses at least two predicted transmembrane domains (TMDs) with nearby clusters of basic amino acid residues, reminiscent of a membrane peroxisomal targeting signal (mPTS). Subcellular localization(s) of transiently-expressed myc-tagged AtPex11a-e in Arabidopsis and BY-2 suspension cells were determined via in vivo immunofluorescence microscopy. Time-course studies (2-24 h post bombardment) revealed that myc-AtPex11a,b,d & e sorted to peroxisomes via a reticular compartment (probably ER subdomains) in both cell types. Expression (22 h) of myc-AtPex11d resulted in peroxisomal elongation, whereas expression (22 h) of myc-AtPex11e for 20-24 h resulted in peroxisomal proliferation (increased number per cell). Necessary components of the putative mPTS on AtPex11e are a cluster of basic amino acid residues flanked by both TMDs. In conclusion, localization of AtPex11a,b,d & e to the ER and peroxisomes, and the changes in peroxisomal morphology imposed by overexpression of AtPex11d & e, support the notion that multiple forms of AtPex11 are structural and functional peroxin homologs. NSF grant MCB-0091826.
