Genome-wide analysis of putative peroxiredoxin in unicellular and filamentous cyanobacteria

Abstract

BackgroundCyanobacteria are photoautotrophic prokaryotes with wide variations in genome sizes and ecological habitats. Peroxiredoxin (PRX) is an important protein that plays essential roles in protecting own cells against reactive oxygen species (ROS). PRXs have been identified from mammals, fungi and higher plants. However, knowledge on cyanobacterial PRXs still remains obscure. With the availability of 37 sequenced cyanobacterial genomes, we performed a comprehensive comparative analysis of PRXs and explored their diversity, distribution, domain structure and evolution.ResultsOverall 244 putative prx genes were identified, which were abundant in filamentous diazotrophic cyanobacteria, Acaryochloris marina MBIC 11017, and unicellular cyanobacteria inhabiting freshwater and hot-springs, while poor in all Prochlorococcus and marine Synechococcus strains. Among these putative genes, 25 open reading frames (ORFs) encoding hypothetical proteins were identified as prx gene family members and the others were already annotated as prx genes. All 244 putative PRXs were classified into five major subfamilies (1-Cys, 2-Cys, BCP, PRX5_like, and PRX-like) according to their domain structures. The catalytic motifs of the cyanobacterial PRXs were similar to those of eukaryotic PRXs and highly conserved in all but the PRX-like subfamily. Classical motif (CXXC) of thioredoxin was detected in protein sequences from the PRX-like subfamily. Phylogenetic tree constructed of catalytic domains coincided well with the domain structures of PRXs and the phylogenies based on 16s rRNA.ConclusionsThe distribution of genes encoding PRXs in different unicellular and filamentous cyanobacteria especially those sub-families like PRX-like or 1-Cys PRX correlate with the genome size, eco-physiology, and physiological properties of the organisms. Cyanobacterial and eukaryotic PRXs share similar conserved motifs, indicating that cyanobacteria adopt similar catalytic mechanisms as eukaryotes. All cyanobacterial PRX proteins share highly similar structures, implying that these genes may originate from a common ancestor. In this study, a general framework of the sequence-structure-function connections of the PRXs was revealed, which may facilitate functional investigations of PRXs in various organisms.

Unraveling the mechanism responsible for the contrasting tolerance of Synechocystis and Synechococcus to Cr(VI): Enzymatic and non-enzymatic antioxidants

“…Genome sequence analysis shows that the major plant peroxidase, ascorbate peroxidase, is generally absent in unicellular bacteria like Synechococcus and Synechocystis (http://genome.microbedb.jp/cyanobase). However, several thiol peroxidases, also called as peroxiredoxins (Prxs), which detoxify peroxides using catalytic cysteines are well represented in cyanobacteria (Cui et al, 2012). Among these, the typical 2-CysPrx that forms the largest group of Prxs is functionally conserved in all kingdoms of life (Dietz, 2011).…”

Oxygen Concentration Inside a Functioning Photosynthetic Cell

“…In addition to singlet oxygen, electron transfer reactions within a living organism can also produce superoxide, peroxide, and hydroxyl radicals (10,(16)(17)(18). These ROS usually escape into a cell and are scavenged at a later time by specialized enzymes such as superoxide dismutases (SODs), catalases, and peroxidases (16,19). In the case of oxygenic photosynthetic cyanobacteria, the majority of these ROS (in particular superoxide) are generated at the F A and F B iron-sulfur centers of photosystem I (18,20).…”

MicroRNA-211 Enhances the Oncogenicity of Carcinogen-Induced Oral Carcinoma by Repressing TCF12 and Increasing Antioxidant Activity

“…Family with sequence similarity 213, member A (FAM213A) was discovered as one of the members in the PRXlike subfamily. Moreover, it also possesses an essential domain for the activation of TRX (36). FAM213A was originally identified during fetal liver development and was activated in M-CSF-stimulated monocytes (38).…”

“…PRXs uptake H 2 O 2 to change into oxidized form. The oxidized PRXs are then reduced by TRXs (36,37). Family with sequence similarity 213, member A (FAM213A) was discovered as one of the members in the PRXlike subfamily.…”