Authors: Andrzej Bodył Paweł Mackiewicz
Publish Date: 2006/12/02
Volume: 187, Issue: 4, Pages: 281-296
Abstract
One of the proteins targeted to the peridinin plastid of the dinoflagellate Lingulodinium polyedrum is the ironcontaining superoxide dismutase LpSOD Like dinoflagellate plastid proteins of class II LpSOD carries a bipartite presequence comprising a signal peptide followed by a transit peptide Our bioinformatic studies suggest that its signal peptide is atypical however and that the entire presequence may function as a mitochondrial targeting signal It is possible that LpSOD represents a new class of proteins in algae with complex plastids which are cotargeted to the plastid and mitochondrion In addition to the ambiguous Nterminal targeting signal LpSOD contains a potential type1 peroxisometargeting signal PTS1 located at its Cterminus In accordance with a peroxisome localization of this dismutase its mRNA has two inframe AUG codons Our bioinformatic analyses indicate that the first start codon resides in a much weaker oligonucleotide context than the second one This suggests that synthesis of the plastid/mitochondriontargeted and peroxisometargeted isoforms could proceed through socalled leaky scanning Moreover our results show that expression of the two isoforms could be regulated by a ‘hairpin’ structure located between the first and second start codons
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