In silico Prediction of Protein-Protein Interaction Network Induced by Manganese II in Meyerozyma guilliermondii.

Recently, there has been an increasing interest in the use of yeast to produce biosorbent materials, because yeast is economical to use, adaptable to a variety of conditions, and amenable to morphological manipulations to yield better raw biomaterials. Previous studies from our laboratory have shown that Meyerozyma guilliermondii, a non-pathogenic haploid yeast (ascomycete), exhibits excellent biosorption capacity for Mn2+, as demonstrated by kinetic analyses. Shotgun/bottom-up analyses of soluble fractions revealed a total of 1257 identified molecules, with 117 proteins expressed in the absence of Mn2+ and 69 expressed only in the presence of Mn2+. In this article, we describe the first in silico prediction and screening of protein-protein interactions (PPIs) in M. guilliermondii using experimental data from shotgun/bottom-up analyses. We also present the categorization of biological processes (BPs), molecular functions (MFs), and metabolic pathways of 71 proteins upregulated in the M. guilliermondii proteome in response to stress caused by an excess of Mn2+ ions. Most of the annotated proteins were related to oxidation-reduction processes, metabolism, and response to oxidative stress. We identified seven functional enrichments and 42 metabolic pathways; most proteins belonged to pathways related to metabolic pathways (19 proteins) followed by the biosynthesis of secondary metabolites (10 proteins) in the presence of Mn2+. Using our data, it is possible to infer that defense mechanisms minimize the impact of Mn2+ via the expression of antioxidant proteins, thus allowing adjustment during the defense response. Previous studies have not considered protein interactions in this genus in a manner that permits comparisons. Consequently, the findings of the current study are innovative, highly relevant, and provide a description of interactive complexes and networks that yield insight into the cellular processes of M. guilliermondii. Collectively, our data will allow researchers to explore the biotechnological potential of M. guilliermondii in future bioremediation processes.

Manganese alters expression of proteins involved in the oxidative stress of Meyerozyma guilliermondii.

Organisms, in general, respond to environmental stress by altering their pattern of protein expression (proteome), as an alternative to growing in stressful conditions. A strain of Meyerozyma guilliermondii resistant to manganese was isolated from a sample of water collected from mine drainage in southeastern Minas Gerais (Brazil), and demonstrated manganese detoxification capacity. Protein extracts containing the soluble fractions were obtained after growth of the strain in the absence and presence of MnSO4. Tryptic peptides recovered from samples were analyzed by liquid chromatography coupled to mass spectrometry (LC-MS/MS). Shotgun/bottom-up analyses of the soluble fractions revealed a total of 1257 identified molecules. Treatment with Mn did not affect the growth of yeast but induced changes in the protein profile, with 117 proteins expressed in the absence of Mn and 69 expressed only in its presence. Most of these are annotated as related to DNA repair, oxidoreductase activity, and remodeling of gene expression. This is the first proteomic report of M. guilliermondii, with promising characteristics for Mn bioremediation, and the first of the genus Meyerozyma. This proteomic characterization may help in the understanding of molecular regulatory mechanisms associated with tolerance to excess Mn, and the potential use of biomass in bioremediation processes. SIGNIFICANCE: Environmental pollution by heavy metals such as manganese (Mn2+) has increased as it is a by-product of the mining industry and a potential environmental contaminant. Many studies have explored the use of bacteria for manganese bioremediation, but yeasts have emerged as a promising alternative, displaying faster growth and greater removal efficiency. Previous works of our laboratory showed that Meyerozyma guilliermondii, a non-pathogenic haploid yeast (ascomycete), has excellent removal and accumulation capacity of Mn2+, potentially useful in bioremediation. Nowadays efforts have been devoted to understanding the physiology of metal hyperaccumulation to gain insights into the molecular basis of hyperaccumulation. To obtain a comprehensive understanding of the molecular mechanism of Mn2+ hyperaccumulation in M. guilliermondii, proteomic approaches were employed yielding the first compositional proteomic map of total soluble proteins and their differential expression in the presence of Mn2+. We believe our findings are of biotechnological interest concerning the utilization of M. guilliermondii for bioremediation purposes.

Alterations in the proteomic composition of Serratia marcescens in response to manganese (II).

BACKGROUND: Proteomics is an important tool for the investigation of dynamic physiological responses of microbes under heavy metal stress. To gain insight into how bacteria respond to manganese (II) and identify the proteins involved in Mn (II) oxidation, the shotgun proteomics approach was applied to a potential Mn (II)-oxidizing Serratia marcescens strain cultivated in the absence and presence of Mn (II). RESULTS: The LG1 strain, which grew equally well in the two conditions, was found to express a set of proteins related to cellular processes vital for survival, as well as proteins involved in adaptation and tolerance to Mn (II). The multicopper oxidase CueO was identified, indicating its probable participation in the Mn (II) bio-oxidation; however, its expression was not modulated by the presence of Mn (II). A set of proteins related to cell and metabolic processes vital to the cells were downregulated in the presence of Mn (II), while cell membrane-related proteins involved in the maintenance of cell integrity and survival under stress were upregulated under this condition. CONCLUSIONS: These findings indicate that the LG1 strain may be applied successfully in the bioremediation of Mn (II), and the shotgun approach provides an efficient means for obtaining the total proteome of this species.