Minisymposium 25: Protein Targeting

Add this abstract to my Itinerary

Abs # M2503: Evidence of alternative translation initiation in plant dual targeting

Presenter:	Christensen, Alan C       Contact Presenter
Authors	Christensen, Alan C (A)   Wamboldt, Yashitola  (B)   Mohammed, Saleem  (A) (B)  Lyznik, Anna  (B)   Mackenzie, Sally A (A) (B)
Affiliations:	(A): School of Biological Sciences, University of Nebraska, Lincoln, NE 68588 (B): Plant Science Initiative, University of Nebraska. Lincoln, NE 68588
Web Site:	http://psiweb.unl.edu/mackenzie

Investigation of the plant mitochondrial and plastid proteomes have revealed a number of proteins that reside within both organelles. Organellar proteins are also found that function both within an organelle and in the cytosol. While studying the protein dual targeting mechanism of organellar gamma type DNA polymerase, we learned that two isoforms of the protein are translated from a single transcript using alternative translation initiation. While AUG initiation results in a plastid targeted form, initiation at a CUG located 7 amino acids upstream produces a mitochondrial form. This non-AUG alternative translation initiation also occurs using in vitro transcription/translation, and a similar phenomenon appears to be employed by up to 10% of the currently identified mitochondrial proteome. We postulate that this mechanism represents a means of modulating dual targeting behavior during plant development, and may provide information regarding the evolution of targeting presequences in plants.