The p53 family of transcription factors plays key roles in development, genome stability, senescence and tumor development, and p53 is the most important tumor suppressor protein in humans. Although intensively investigated for many years, its initial evolutionary history is not yet fully elucidated. Using bioinformatic and structure prediction methods on current databases containing newly-sequenced genomes and transcriptomes, we present a detailed characterization of p53 family homologs in remote members of the Holozoa group, in the unicellular clades Filasterea, Ichthyosporea and Corallochytrea. Moreover, we show that these newly characterized homologous sequences contain domains that can form structures with high similarity to the human p53 family DNA-binding domain, and some also show similarities to the oligomerization and SAM domains. The presence of these remote homologs demonstrates an ancient origin of the p53 protein family.

• MeSH
• Databases, Genetic MeSH
• Eukaryota classification   genetics   MeSH
• Exons MeSH
• Phylogeny MeSH
• Protein Interaction Domains and Motifs MeSH
• Introns MeSH
• Protein Conformation MeSH
• Evolution, Molecular * MeSH
• Models, Molecular MeSH
• Multigene Family * MeSH
• Tumor Suppressor Protein p53 chemistry   genetics   metabolism   MeSH
• Amino Acid Sequence MeSH
• Sequence Homology, Amino Acid * MeSH
• Publication type
• Journal Article MeSH

The role of local DNA structures in the regulation of basic cellular processes is an emerging field of research. Amongst local non-B DNA structures, the significance of G-quadruplexes was demonstrated in the last decade, and their presence and functional relevance has been demonstrated in many genomes, including humans. In this study, we analyzed the presence and locations of G-quadruplex-forming sequences by G4Hunter in all complete bacterial genomes available in the NCBI database. G-quadruplex-forming sequences were identified in all species, however the frequency differed significantly across evolutionary groups. The highest frequency of G-quadruplex forming sequences was detected in the subgroup Deinococcus-Thermus, and the lowest frequency in Thermotogae. G-quadruplex forming sequences are non-randomly distributed and are favored in various evolutionary groups. G-quadruplex-forming sequences are enriched in ncRNA segments followed by mRNAs. Analyses of surrounding sequences showed G-quadruplex-forming sequences around tRNA and regulatory sequences. These data point to the unique and non-random localization of G-quadruplex-forming sequences in bacterial genomes.

• MeSH
• Bacteria genetics   MeSH
• DNA, Bacterial chemistry   MeSH
• Phylogeny MeSH
• G-Quadruplexes * MeSH
• Genome, Bacterial MeSH
• Nucleic Acid Conformation MeSH
• Humans MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH