New Provisional Function of OmpA from Acinetobacter sp. Strain SA01 Based on Environmental Challenges

• Published in: mSystems 2021-01, Vol.6 (1)
• Main Authors: Shahryari, Shahab, Talaee, Mahbubeh, Haghbeen, Kamahldin, Adrian, Lorenz, Vali, Hojatollah, Shahbani Zahiri, Hossein, Noghabi, Kambiz Akbari
• Format: Article
• Language: English
• Subjects: Applied and Environmental Science; Research Article
• ISSN: 2379-5077; 2379-5077
• DOI: 10.1128/mSystems.01175-20

An outer membrane protein A (OmpA) from sp. strain SA01 was identified and characterized in-depth based on the structural and functional characteristics already known of its homologues. structural studies showed that this protein can be a slow porin, binds to peptidoglycan, and exhibits emulsifying properties. Characterization of the recombinant SA01-OmpA, based on its emulsifying properties, represented its promising potentials in biotechnology. Also, the presence of SA01-OmpA in outer membrane vesicles (OMV) and biofilm showed that this protein, like its homologues in , can be secreted into the extracellular environment through OMVs and play a role in the formation of biofilm. After ensuring the correct selection of the protein of interest, the role of oxidative stress induced by cell nutritional parameters (utilization of specific carbon sources) on the expression level of OmpA was carefully studied. For this purpose, the oxidative stress level of SA01 cell cultures in the presence of three nonrelevant carbon sources (sodium acetate, ethanol, and phenol) was examined under each condition. High expression of SA01-OmpA in ethanol- and phenol-fed cells with higher levels of oxidative stress than acetate suggested that oxidative stress could be a substantial factor in the regulation of SA01-OmpA expression. The significant association of SA01-OmpA expression with the levels of oxidative stress induced by cadmium and H O , with oxidative stress-inducing properties and lack of nutritional value, confirmed that the cells tend to harness their capacities with a possible increase in OmpA production. Collectively, this study suggests a homeostasis role for OmpA in sp. SA01 under oxidative stress besides assuming many other roles hitherto attributed to this protein. OmpA is known as a multifaceted protein with multiple functions, including emulsifying properties. Bioemulsifiers are surface-active compounds that can disperse hydrophobic compounds in water and help increase the bioavailability of hydrophobic hydrocarbons to be used by degrading microorganisms. In this study, an OmpA from sp. SA01 was identified and introduced as an emulsifier with a higher emulsifying capacity than rhamnolipid. We also showed that the expression of this protein is not dependent on the nutritional requirements but is more influenced by the oxidative stress caused by stressors. This finding, along with the structural role of this protein as a slow porin or its role in OMV biogenesis a