Functional annotation of hypothetical proteins from the Exiguobacterium antarcticum strain B7 reveals proteins involved in adaptation to extreme environments, including high arsenic resistance

• Published in: PloS one Vol. 13; no. 6; p. e0198965
• Main Authors: da Costa, Wana Lailan Oliveira, Araújo, Carlos Leonardo de Aragão, Dias, Larissa Maranhão, Pereira, Lino César de Sousa, Alves, Jorianne Thyeska Castro, Araújo, Fabrício Almeida, Folador, Edson Luiz, Henriques, Isabel, Silva, Artur, Folador, Adriana Ribeiro Carneiro
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 25-06-2018; Public Library of Science (PLoS)
• Subjects: Adaptation; Adaptation, Physiological; Amino acids; Annotations; Arsenic; Arsenic - toxicity; B7 antigen; Bacillaceae - physiology; Bacteria; Bacterial genetics; Bacterial proteins; Bacterial Proteins - genetics; Bacterial Proteins - physiology; Biofilms; Bioinformatics; Biology; Biology and Life Sciences; Biosynthesis; Biotechnology - methods; Carotenoids; Cellular structure; Cold; Computational Biology; Computer and Information Sciences; Extreme Environments; Flagella; Genes, Bacterial - genetics; Genetic aspects; Genomes; Genomics; Gram-positive bacteria; Laboratories; Localization; Metal concentrations; Microbiological research; Molecular Sequence Annotation; Physical Sciences; Pollution tolerance; Properties; Protein interaction; Protein structure; Proteins; Research and Analysis Methods; Sequence Analysis, DNA; Staphylococcus aureus; Structural analysis; Workflow; Brazil
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0198965

Exiguobacterium antarcticum strain B7 is a psychrophilic Gram-positive bacterium that possesses enzymes that can be used for several biotechnological applications. However, many proteins from its genome are considered hypothetical proteins (HPs). These functionally unknown proteins may indicate important functions regarding the biological role of this bacterium, and the use of bioinformatics tools can assist in the biological understanding of this organism through functional annotation analysis. Thus, our study aimed to assign functions to proteins previously described as HPs, present in the genome of E. antarcticum B7. We used an extensive in silico workflow combining several bioinformatics tools for function annotation, sub-cellular localization and physicochemical characterization, three-dimensional structure determination, and protein-protein interactions. This genome contains 2772 genes, of which 765 CDS were annotated as HPs. The amino acid sequences of all HPs were submitted to our workflow and we successfully attributed function to 132 HPs. We identified 11 proteins that play important roles in the mechanisms of adaptation to adverse environments, such as flagellar biosynthesis, biofilm formation, carotenoids biosynthesis, and others. In addition, three predicted HPs are possibly related to arsenic tolerance. Through an in vitro assay, we verified that E. antarcticum B7 can grow at high concentrations of this metal. The approach used was important to precisely assign function to proteins from diverse classes and to infer relationships with proteins with functions already described in the literature. This approach aims to produce a better understanding of the mechanism by which this bacterium adapts to extreme environments and to the finding of targets with biotechnological interest.