Novel antimicrobial activity of protein produced by Streptomyces lividans TK24 against the phytopathogen Clavibacter michiganensis.

Antimicrobial proteins and peptides are an alternative to current antibiotics. Here, we report an antimicrobial activity in a low-molecular-weight protein secreted naturally by Streptomyces lividans TK24 when glucose or glycerol were used as carbon sources. The antimicrobial activity was demonstrated against Bacillus subtilis, Bacillus cereus, Kokuria rhizophila, Clostridium sporogenes and Clavibacter michiganensis, causal pathogen of tomato bacterial canker; one of the most destructive bacterial diseases of this crop. The protein fraction with antimicrobial activity was identified and quantified by LC-MS/MS. From a total of 155 proteins, 11 were found to be within the range of 11.3-13.9 kDa of which four proteins were selected by functional analysis as possibly responsible for the antimicrobial activity. Protein fractionation, correlation analysis between antimicrobial activity and abundance of selected proteins, as well as transcriptional expression analysis, indicate that 50S ribosomal protein L19 is the main candidate responsible for antimicrobial activity.

Ribosomes: The New Role of Ribosomal Proteins as Natural Antimicrobials.

Moonlighting proteins are those capable of performing more than one biochemical or biophysical function within the same polypeptide chain. They have been a recent focus of research due to their potential applications in the health, pharmacological, and nutritional sciences. Among them, some ribosomal proteins involved in assembly and protein translation have also shown other functionalities, including inhibiting infectious bacteria, viruses, parasites, fungi, and tumor cells. Therefore, they may be considered antimicrobial peptides (AMPs). However, information regarding the mechanism of action of ribosomal proteins as AMPs is not yet fully understood. Researchers have suggested that the antimicrobial activity of ribosomal proteins may be associated with an increase in intracellular reactive oxidative species (ROS) in target cells, which, in turn, could affect membrane integrity and cause their inactivation and death. Moreover, the global overuse of antibiotics has resulted in an increase in pathogenic bacteria resistant to common antibiotics. Therefore, AMPs such as ribosomal proteins may have potential applications in the pharmaceutical and food industries in the place of antibiotics. This article provides an overview of the potential roles of ribosomes and AMP ribosomal proteins in conjunction with their potential applications.

Proteomic analysis of the signaling pathway mediated by the heterotrimeric Gα protein Pga1 of Penicillium chrysogenum.

BACKGROUND: The heterotrimeric Gα protein Pga1-mediated signaling pathway regulates the entire developmental program in Penicillium chrysogenum, from spore germination to the formation of conidia. In addition it participates in the regulation of penicillin biosynthesis. We aimed to advance the understanding of this key signaling pathway using a proteomics approach, a powerful tool to identify effectors participating in signal transduction pathways. RESULTS: Penicillium chrysogenum mutants with different levels of activity of the Pga1-mediated signaling pathway were used to perform comparative proteomic analyses by 2D-DIGE and LC-MS/MS. Thirty proteins were identified which showed differences in abundance dependent on Pga1 activity level. By modifying the intracellular levels of cAMP we could establish cAMP-dependent and cAMP-independent pathways in Pga1-mediated signaling. Pga1 was shown to regulate abundance of enzymes in primary metabolic pathways involved in ATP, NADPH and cysteine biosynthesis, compounds that are needed for high levels of penicillin production. An in vivo phosphorylated protein containing a pleckstrin homology domain was identified; this protein is a candidate for signal transduction activity. Proteins with possible roles in purine metabolism, protein folding, stress response and morphogenesis were also identified whose abundance was regulated by Pga1 signaling. CONCLUSIONS: Thirty proteins whose abundance was regulated by the Pga1-mediated signaling pathway were identified. These proteins are involved in primary metabolism, stress response, development and signal transduction. A model describing the pathways through which Pga1 signaling regulates different cellular processes is proposed.

Probiotic Properties and Proteomic Analysis of Pediococcus pentosaceus 1101.

Pediococcus pentosaceus 1101 was identified by using 16S rRNA and MALDI-Biotyper. The strain was exposed to conditions that resemble the gastrointestinal tract (GT) to evaluate its probiotic properties. That included the growth kinetics, proteolytic and inhibitory activities within a pH range, survival at low pH and in the presence of bile salts, antagonistic activity, cell-adhesion properties, and antibiotic resistance. The evaluation was followed by a genomic and proteomic analysis that involved the identification of proteins obtained under control and gastrointestinal conditions. The strain showed antagonistic activity against Gram-negative and Gram-positive bacteria, high resistance to acidity (87% logarithmic survival rate, pH 2) and bile salts (99% logarithmic survival rate, 0.5% w/v), and hydrophobic binding, as well as sensitivity to penicillin, amoxicillin, and chloramphenicol. On the other hand, P. pentosaceus 1101 has a genome size of 1.76 Mbp, with 1754 coding sequences, 55 rRNAs, and 33 tRNAs. The proteomic analysis showed that 120 proteins were involved in mechanisms in which the strain senses the effects of acid and bile salts. Moreover, the strain produces at least one lytic enzyme (N-acetylmuramoyl-L-alanine amidase; 32 kDa) that may be related to the antimicrobial activity. Therefore, proteins identified might be a key factor when it comes to the adaptation of P. pentosaceus 1101 into the GT and associated with its technological and probiotic properties.

H2O2 Induces Major Phosphorylation Changes in Critical Regulators of Signal Transduction, Gene Expression, Metabolism and Developmental Networks in Aspergillus nidulans.

Reactive oxygen species (ROS) regulate several aspects of cell physiology in filamentous fungi including the antioxidant response and development. However, little is known about the signaling pathways involved in these processes. Here, we report Aspergillus nidulans global phosphoproteome during mycelial growth and show that under these conditions, H2O2 induces major changes in protein phosphorylation. Among the 1964 phosphoproteins we identified, H2O2 induced the phosphorylation of 131 proteins at one or more sites as well as the dephosphorylation of a larger set of proteins. A detailed analysis of these phosphoproteins shows that H2O2 affected the phosphorylation of critical regulatory nodes of phosphoinositide, MAPK, and TOR signaling as well as the phosphorylation of multiple proteins involved in the regulation of gene expression, primary and secondary metabolism, and development. Our results provide a novel and extensive protein phosphorylation landscape in A. nidulans, indicating that H2O2 induces a shift in general metabolism from anabolic to catabolic, and the activation of multiple stress survival pathways. Our results expand the significance of H2O2 in eukaryotic cell signaling.

Solid-state fermentation increases secretome complexity in Aspergillus brasiliensis.

Aspergillus is used for the industrial production of enzymes and organic acids, mainly by submerged fermentation (SmF). However, solid-state fermentation (SSF) offers several advantages over SmF. Although differences related to lower catabolite repression and substrate inhibition, as well as higher extracellular enzyme production in SSF compared to SmF have been shown, the mechanisms undelaying such differences are still unknown. To explain some differences among SSF and SmF, the secretome of Aspergillus brasiliensis obtained from cultures in a homogeneous physiological state with high glucose concentrations was analyzed. Of the regulated proteins produced by SmF, 74% were downregulated by increasing the glucose concentration, whereas all those produced by SSF were upregulated. The most abundant and upregulated protein found in SSF was the transaldolase, which could perform a moonlighting function in fungal adhesion to the solid support. This study evidenced that SSF: (i) improves the kinetic parameters in relation to SmF, (ii) prevents the catabolite repression, (iii) increases the branching level of hyphae and oxidative metabolism, as well as the concentration and diversity of secreted proteins, and (iv) favors the secretion of typically intracellular proteins that could be involved in fungal adhesion. All these differences can be related to the fact that molds are more specialized to growth in solid materials because they mimic their natural habitat.

NeVOmics: An Enrichment Tool for Gene Ontology and Functional Network Analysis and Visualization of Data from OMICs Technologies.

The increasing number of OMICs studies demands bioinformatic tools that aid in the analysis of large sets of genes or proteins to understand their roles in the cell and establish functional networks and pathways. In the last decade, over-representation or enrichment tools have played a successful role in the functional analysis of large gene/protein lists, which is evidenced by thousands of publications citing these tools. However, in most cases the results of these analyses are long lists of biological terms associated to proteins that are difficult to digest and interpret. Here we present NeVOmics, Network-based Visualization for Omics, a functional enrichment analysis tool that identifies statistically over-represented biological terms within a given gene/protein set. This tool provides a hypergeometric distribution test to calculate significantly enriched biological terms, and facilitates analysis on cluster distribution and relationship of proteins to processes and pathways. NeVOmics is adapted to use updated information from the two main annotation databases: Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG). NeVOmics compares favorably to other Gene Ontology and enrichment tools regarding coverage in the identification of biological terms. NeVOmics can also build different network-based graphical representations from the enrichment results, which makes it an integrative tool that greatly facilitates interpretation of results obtained by OMICs approaches. NeVOmics is freely accessible at https://github.com/bioinfproject/bioinfo/.

The oxygen concentration in cultures modulates protein expression and enzymatic antioxidant responses in Metarhizium lepidiotae conidia.

Conidia from Metarhizium spp. are used for integrated pest control; however, environmental factors diminish the effectivity of these programs. Several approaches tried to improve conidia resistance to overcome this limitation, although little is known about the mechanisms involved in this effect. Here we measured the activity of antioxidant enzymes and conidia virulence, comparing the proteomic profiles of Metarhiziumlepidiotae CP-OAX conidia produced under normal (21% O2) and high oxygen atmospheres (pulses with 30% O2). We detected a higher virulence against Tenebrio molitor larvae, in addition to an increase in ultraviolet light tolerance in conidia produced under 30% O2, which correlates with increased glutathione reductase activity. Two-dimensional gel electrophoresis (2D SDS-PAGE) of proteins extracted in conidia harvested from both experimental conditions revealed a group of proteins that was observed only in conidia from oxidant atmospheres. Some of those proteins were directly involved in oxidative stress responses, whereas others were involved in conidial virulence, thermo-tolerance, and the central metabolism. Thus, a high atmospheric oxygen concentration (30%) activates antioxidant defence and general stress response mechanisms involved in conidia resistance to adverse environmental factors, which can ultimately translate into higher effectivity for the use of entomopathogenic fungi conidia in pest control.