Abstract
Background Chromobacterium violaceum is a bacterium commonly found in tropical and subtropical regions and is associated with important pharmacological and industrial attributes such as producing substances with therapeutic properties and synthesizing biodegradable polymers. Its genome was sequenced, however, approximately 40% of its genes still remain with unknown functions. Although C. violaceum is known by its versatile capacity of living in a wide range of environments, little is known on how it achieves such success. Here, we investigated the proteomic profile of C. violaceum cultivated in the absence and presence of high iron concentration, describing some proteins of unknown function that might play an important role in iron homeostasis, amongst others.ResultsBriefly, C. violaceum was cultivated in the absence and in the presence of 9 mM of iron during four hours. Total proteins were identified by LC-MS and through the PatternLab pipeline. Our proteomic analysis indicates major changes in the energetic metabolism, and alterations in the synthesis of key transport and stress proteins. In addition, it may suggest the presence of a yet unidentified operon that could be related to oxidative stress, together with a set of other proteins with unknown function. The protein-protein interaction network also pinpointed the importance of energetic metabolism proteins to the acclimatation of C. violaceum in high concentration of iron.ConclusionsThis is the first proteomic analysis of the opportunistic pathogen C. violaceum in the presence of high iron concentration. Our data allowed us to identify a yet undescribed operon that might have a role in oxidative stress defense. Our work provides new data that will contribute to understand how this bacterium achieve its capacity of surviving in harsh conditions as well as to open a way to explore the yet little availed biotechnological characteristics of this bacterium with the further exploring of the proteins of unknown function that we showed to be up-regulated in high iron concentration.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-014-0267-6) contains supplementary material, which is available to authorized users.
Highlights
Chromobacterium violaceum is a bacterium commonly found in tropical and subtropical regions and is associated with important pharmacological and industrial attributes such as producing substances with therapeutic properties and synthesizing biodegradable polymers
The OD measurement (Additional file 2) showed that the iron treatment leads to a growth arrest in C. violaceum from this assay, we cannot see a death tendency caused by the experimental condition, suggesting that this bacterium has a mechanism to withstand this elevated iron exposure
C. violaceum antioxidant profile We evaluated if the iron concentration used in the experiment can induce oxidative stress by assessing the catalase and superoxide dismutase enzymatic activities and the total antioxidant activity from the C. violaceum protein extract
Summary
Chromobacterium violaceum is a bacterium commonly found in tropical and subtropical regions and is associated with important pharmacological and industrial attributes such as producing substances with therapeutic properties and synthesizing biodegradable polymers. Approximately 40% of its genes still remain with unknown functions. We investigated the proteomic profile of C. violaceum cultivated in the absence and presence of high iron concentration, describing some proteins of unknown function that might play an important role in iron homeostasis, amongst others. Approximately 40% of its ORFs remain with unknown functions which make this organism a target for prospecting genes with biotechnological properties. Previous reports have described several key aspects of C. violaceum, such as having great metabolic versatility presenting several ORFs related to osmotic stress, response to heat, oxidative stress, DNA repair, and a large number of proteins involved in iron metabolism [9,10]. High concentrations of this metal can lead to oxidative stress which causes damage to biomolecules and the death of the organism or cell [17]
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