Specification of the Peroxisome Targeting Signals Type 1 and Type 2 of Plant Peroxisomes by Bioinformatics Analyses  

Abstract

To specify the C-terminal peroxisome targeting signal type 1 (PTS1) and the N-terminal PTS2 for higher plants, a maximum number of plant cDNAs and expressed sequence tags that are homologous to PTS1-and PTS2-targeted plant proteins was retrieved from the public databases and the primary structure of their targeting domains was analyzed for conserved properties. According to their high overall frequency in the homologs and their widespread occurence in different orthologous groups, nine major PTS1 tripeptides ([SA][RK] [LM]. without AKM. plus SRI. and PRL.) and two major PTS2 nonapeptides (R[LI]x 5 HL) were defined that are considered good indicators for peroxisomal localization if present in unknown proteins. A lower but significant number of homologs contained 1 of 11 minor PTS1 tripeptides or of 9 minor PTS2 nonapeptides, many of which have not been identified before in plant peroxisomal proteins. The region adjacent to the PTS peptides was characterized by specific conserved properties as well, such as a pronounced incidence of basic and Pro residues and a high positive net charge, which probably play an auxiliary role in peroxisomal targeting. By contrast, several peptides with assumed peroxisomal targeting properties were not found in any of the 550 homologs and hence play-if at all-only a minor role in peroxisomal targeting. Based on the definition of these major and minor PTS and on the recognition of additional conserved properties, the accuracy of predicting peroxisomal proteins can be raised and plant genomes can be screened for novel proteins of peroxisomes more successfully.

Peroxisomes Are Required for in Vivo Nitric Oxide Accumulation in the Cytosol following Salinity Stress of Arabidopsis Plants

“…Peroxisomes are cell compartments involved in many physiological functions, such as lipid mobilization, photorespiration, and hormone biosynthesis under normal and stress conditions (del Río et al, 1992;Hayashi and Nishimura, 2003;Reumann, 2004;Pracharoenwattana and Smith, 2008;Corpas et al, 2009a). NO, a free radical generated in animal and plant cells, has attracted the attention of many researchers due to its involvement in various physiological processes, such as seed germination, plant development, and senescence (Leshem, 1996;Corpas et al, 2004Corpas et al, , 2006 as well as abiotic and biotic stress (Corpas et al, 2007a(Corpas et al, , 2008Besson-Bard et al, 2008;Neill et al, 2008;Chaki et al, 2009a).…”

Purification and Characterization of the FeII- and α-Ketoglutarate-Dependent Xanthine Hydroxylase from Aspergillus nidulans

“…A urate oxidase-green fluorescent protein fusion shows a particulate intracellular distribution in Aspergillus nidulans, fully consistent with a peroxisomal localization (G. Langousis and G. Diallinas, unpublished data). XanA does not possess a C-terminal peroxisomal targeting signal (variations of an SKL tripeptide, denoted PTS1); however, it contains a RSALYTHL sequence (residues 40-47) that resembles the PTS2 N-terminal import sequence (variations of RLX 5 HL) found in a minority of peroxisomal proteins throughout the eukaryotes (54)(55)(56). In some instances, including mammalian (57), yeast (58), and plant (59) peroxisomal proteins, it has been shown that the PST2 is contained in a pre-sequence that is cleaved upon peroxisomal entry.…”

Inactivation of an aminoaldehyde dehydrogenase is responsible for fragrance in rice

“…Many recent studies have found plant BADs are capable of metabolising a range of substrates including omega-aminoaldehydes, often more efficiently than bet-ald (Trossat et al 1997;Incharoensakdi et al 2000;Livingstone et al 2003;Oishi and Ebina 2005), while others report enzymes with aminoaldehyde dehydrogenase (AAD) activity that have high homology to BADs but no affinity for bet-ald (Sebela et al 2000), leading to the suggestion BADs and AADs are the same enzyme and should be reclassified as such (Sebela et al 2000;Livingstone et al 2003;Reumann 2004).…”