Antibiotics versus biofilm: an emerging battleground in microbial communities

Biofilm is a complex structure of microbiome having different bacterial colonies or single type of cells in a group; adhere to the surface. These cells are embedded in extracellular polymeric substances, a matrix which is generally composed of eDNA, proteins and polysaccharides, showed high resistance to antibiotics. It is one of the major causes of infection persistence especially in nosocomial settings through indwelling devices. Quorum sensing plays an important role in regulating the biofilm formation. There are many approaches being used to control infections by suppressing its formation but CRISPR-CAS (gene editing technique) and photo dynamic therapy (PDT) are proposed to be used as therapeutic approaches to subside bacterial biofim infections, especially caused by deadly drug resistant bad bugs.

Necroptosis: a regulated inflammatory mode of cell death

Programmed cell death has a vital role in embryonic development and tissue homeostasis. Necroptosis is an alternative mode of regulated cell death mimicking features of apoptosis and necrosis. Necroptosis requires protein RIPK3 (previously well recognized as regulator of inflammation, cell survival, and disease) and its substrate MLKL, the crucial players of this pathway. Necroptosis is induced by toll-like receptor, death receptor, interferon, and some other mediators. Shreds of evidence based on a mouse model reveals that deregulation of necroptosis has been found to be associated with pathological conditions like cancer, neurodegenerative diseases, and inflammatory diseases. In this timeline article, we are discussing the molecular mechanisms of necroptosis and its relevance to diseases.

Effective Antimicrobial Activity of Green ZnO Nano Particles of Catharanthus roseus

In the present study, zinc oxide nanoparticles (ZnO NPs) were synthesized using leaf extract of Catharanthus roseus (C. roseus) under different physical parameters. Biosynthesis of ZnO NPs was confirmed by UV-Visible spectrophotometer and further, characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy-Dispersive X-ray spectroscopy (EDX), Atomic Force Microscopy (AFM), Photoluminescence study and Dynamic Light Scattering (DLS). We have also confirmed that several physical parameters such as pH, temperature, concentration of metal ions and reaction time were able to regulate shape and size of synthesized ZnO NPs. XRD and TEM analysis provided the information about the average size and hexagonal morphology of ZnO NPs. FTIR spectra analysis suggested that phenolic compounds played crucial role in the biosynthesis of ZnO NPs. The significant antibacterial activity of ZnO NPs was observed against Staphylococcus aureus MTCC 9760 (S. aureus), Streptococcus pyogenes MTCC 1926 (S. pyogenes), Bacillus cereus MTCC 430 (B. cereus), Pseudomonas aeruginosa MTCC 424 (P. aeruginosa), Proteus mirabilis MTCC 3310 (P. mirabilis) and Escherichia coli MTCC 40 (E. coli). The synthesized ZnO NPs have shown antibacterial efficacy against both Gram-positive and Gram-negative pathogens. Synergistic effects of ZnO NPs and streptomycin showed increased efficacy as indicated by the increased zone of clearance in comparison to their individual effects (either ZnO NPs or streptomycin). Overall, the results elucidated a rapid, cost-effective, environmentally friendly and convenient method for ZnO NPs synthesis, which could be used as a potential antimicrobial agent against drug resistant microbes.

Proteomic analysis of Mycobacterium tuberculosis isolates resistant to kanamycin and amikacin

Kanamycin (KM) and amikacin (AK) are the key aminoglycoside drugs against tuberculosis (TB) and resistance to them severely affects the options for treatment. Many explanations have been proposed for drug resistance to these drugs but still some mechanisms are unknown. Proteins are the functional moiety of the cell and manifest in most of the biological processes; so, these are potential foci for the development of new therapeutics, diagnostics and vaccine. We examined the KM and AK resistant isolates of Mycobacterium tuberculosis using proteomic analysis comprising of two dimensional gel electrophoresis (2DGE), matrix assisted laser desorption ionization time-of-flight/time-of flight (MALDI-TOF/TOF) and bioinformatic tools like BLASTP, InterProScan, KEGG motif scan and molecular docking. Proteins intensities of twelve spots were found to be consistently increased in KM and AK resistant isolates and these were identified as Rv3867, Rv1932, Rv3418c, Rv1876, Rv2031c, Rv0155, Rv0643c, Rv3224, Rv0952, and Rv0440. Among these, Rv3867 and Rv3224 were identified as proteins with unknown function. All the proteins identified were cellular proteins. Molecular docking shows the proper interaction of both drugs with these molecules. Also, Rv1876 and Rv3224 were found to be probably involved in iron regulation/metabolism indicating the role of iron in imparting resistance to second line drugs.

BIOLOGICAL SIGNIFICANCE

The study that was carried out shows that two dimensional electrophoresis along with mass spectrometry is still the best approach for proteomic analysis. To the best of our knowledge it is the first ever report on proteomic analysis of M. tuberculosis isolates resistant to second line drugs (kanamycin and amikacin). The major finding implicates that the genes/proteins involved in iron metabolism and the two hypothetical proteins (Rv3867 and Rv3224) might be playing some crucial role in contributing resistance to second line drugs. Further exploitation in this direction may lead to the development of newer therapeutics against tuberculosis.

Comparative Proteomic Analysis of Aminoglycosides Resistant and Susceptible Mycobacterium tuberculosis Clinical Isolates for Exploring Potential Drug Targets

Aminoglycosides, amikacin (AK) and kanamycin (KM) are second line anti-tuberculosis drugs used to treat tuberculosis (TB) and resistance to them affects the treatment. Membrane and membrane associated proteins have an anticipated role in biological processes and pathogenesis and are potential targets for the development of new diagnostics/vaccine/therapeutics. In this study we compared membrane and membrane associated proteins of AK and KM resistant and susceptible Mycobacterium tuberculosis isolates by 2DE coupled with MALDI-TOF/TOF-MS and bioinformatic tools. Twelve proteins were found to have increased intensities (PDQuest Advanced Software) in resistant isolates and were identified as ATP synthase subunit alpha (Rv1308), Trigger factor (Rv2462c), Dihydrolipoyl dehydrogenase (Rv0462), Elongation factor Tu (Rv0685), Transcriptional regulator MoxR1(Rv1479), Universal stress protein (Rv2005c), 35kDa hypothetical protein (Rv2744c), Proteasome subunit alpha (Rv2109c), Putative short-chain type dehydrogenase/reductase (Rv0148), Bacterioferritin (Rv1876), Ferritin (Rv3841) and Alpha-crystallin/HspX (Rv2031c). Among these Rv2005c, Rv2744c and Rv0148 are proteins with unknown functions. Docking showed that both drugs bind to the conserved domain (Usp, PspA and SDR domain) of these hypothetical proteins and GPS-PUP predicted potential pupylation sites within them. Increased intensities of these proteins and proteasome subunit alpha might not only be neutralized/modulated the drug molecules but also involved in protein turnover to overcome the AK and KM resistance. Besides that Rv1876, Rv3841 and Rv0685 were found to be associated with iron regulation signifying the role of iron in resistance. Further research is needed to explore how these potential protein targets contribute to resistance of AK and KM.

Proteomic analysis of ofloxacin-mono resistant Mycobacterium tuberculosis isolates

Drug resistance particularly, multi drug resistance tuberculosis (MDR-TB) has emerged as a major problem in the chemotherapy of tuberculosis. Ofloxacin (OFX) has been used as second-line drug against MDR-TB. The principal target of the OFX is DNA gyrase encoded by gyrA and gyrB genes. Many explanations have been proposed for drug resistance to OFX but still some mechanisms are unknown. As proteins manifest most of the biological processes, these are attractive targets for developing drugs and diagnostics/therapeutics. We examined the OFX resistant Mycobacterium tuberculosis isolates by proteomic approach (2DE-MALDI-TOF-MS) and bioinformatic tools under OFX induced conditions. Our study showed fourteen proteins (Rv0685, Rv0363c, Rv2744c, Rv3803c, Rv2534c, Rv2140c, Rv1475c, Rv0440, Rv2245, Rv1436, Rv3551, Rv0148, Rv2882c and Rv0733) with increased intensities in OFX resistant and OFX induced as compared to susceptible isolates. Bioinformatic analysis of hypothetical proteins (Rv2744c, Rv2140c, Rv3551 and Rv0148) revealed the presence of conserved motifs and domains. Molecular docking showed proper interaction of OFX with residues of conserved motifs. These proteins might be involved in the OFX modulation/neutralization and act as novel resistance mechanisms as well as potential for diagnostics and drug targets against OFX resistance. This article is part of a Special Issue entitled: Proteomics in India.

Molecular mechanisms of underlying genetic factors and associated mutations for drug resistance in Mycobacterium tuberculosis

Nowadays, drug-resistant tuberculosis (DR-TB) and co-infected tuberculosis (CI-TB) strains are the leading cause for the enhancement of long-term morbidity and unpredicted mortality rates from this ghoulish acid fast-bacterium infection, globally. Unfortunately, the lack of/ample lethargic towards the development of compelling anti-TB regimens with a large-scale prevalence rate is a great challenge towards control of the pandemic situation. Indeed, the recent improvement in genomic studies for early diagnosis and understanding the mechanisms of drug resistance, as well as the identification of newer drug targets is quite remarkable and promising. Mainly, identification of such genetic factors, chromosomal mutations and associated pathways gives new ray of hope in current anti-TB drug discovery. This focused review provides molecular insights into the updated drug resistance mechanisms with encoded bacilli genetic factors as a novel target and potential source of development with screened-out newer anti-TB agents towards the control of MDR-TB soon.

Cytosolic Proteome Profiling of Aminoglycosides Resistant Mycobacterium tuberculosis Clinical Isolates Using MALDI-TOF/MS

Emergence of extensively drug resistant tuberculosis (XDR-TB) is the consequence of the failure of second line TB treatment. Aminoglycosides are the important second line anti-TB drugs used to treat the multi drug resistant tuberculosis (MDR-TB). Main known mechanism of action of aminoglycosides is to inhibit the protein synthesis by inhibiting the normal functioning of ribosome. Primary target of aminoglycosides are the ribosomal RNA and its associated proteins. Various mechanisms have been proposed for aminoglycosides resistance but still some are unsolved. As proteins are involved in most of the biological processes, these act as a potential diagnostic markers and drug targets. In the present study we analyzed the purely cytosolic proteome of amikacin (AK) and kanamycin (KM) resistant Mycobacterium tuberculosis isolates by proteomic and bioinformatic approaches. Twenty protein spots were found to have over expressed in resistant isolates and were identified. Among these Rv3208A, Rv2623, Rv1360, Rv2140c, Rv1636, and Rv2185c are six proteins with unknown functions or undefined role. Docking results showed that AK and KM binds to the conserved domain (DUF, USP-A, Luciferase, PEBP and Polyketidecyclase/dehydrase domain) of these hypothetical proteins and over expression of these proteins might neutralize/modulate the effect of drug molecules. TBPred and GPS-PUP predicted cytoplasmic nature and potential pupylation sites within these identified proteins, respectively. String analysis also suggested that over expressed proteins along with their interactive partners might be involved in aminoglycosides resistance. Cumulative effect of these over expressed proteins could be involved in AK and KM resistance by mitigating the toxicity, repression of drug target and neutralizing affect. These findings need further exploitation for the expansion of newer therapeutics or diagnostic markers against AK and KM resistance so that an extreme condition like XDR-TB can be prevented.

Role of Bacterioferritin & Ferritin in M. tuberculosis Pathogenesis and Drug Resistance: A Future Perspective by Interactomic Approach

Tuberculosis is caused by Mycobacterium tuberculosis, one of the most successful and deadliest human pathogen. Aminoglycosides resistance leads to emergence of extremely drug resistant strains of M. tuberculosis. Iron is crucial for the biological functions of the cells. Iron assimilation, storage and their utilization is not only involved in pathogenesis but also in emergence of drug resistance strains. We previously reported that iron storing proteins (bacterioferritin and ferritin) were found to be overexpressed in aminoglycosides resistant isolates. In this study we performed the STRING analysis of bacterioferritin & ferritin proteins and predicted their interactive partners [ferrochelatase (hemH), Rv1877 (hypothetical protein/probable conserved integral membrane protein), uroporphyrinogen decarboxylase (hemE) trigger factor (tig), transcriptional regulatory protein (MT3948), hypothetical protein (MT1928), glnA3 (glutamine synthetase), molecular chaperone GroEL (groEL1 & hsp65), and hypothetical protein (MT3947)]. We suggested that interactive partners of bacterioferritin and ferritin are directly or indirectly involved in M. tuberculosis growth, homeostasis, iron assimilation, virulence, resistance, and stresses.

Proteome analysis of ofloxacin and moxifloxacin induced mycobacterium tuberculosis isolates by proteomic approach

Ofloxacin (OFX) and moxifloxacin (MOX) are the most promising second line drugs for tuberculosis treatment. Although the primary mechanism of action of OFX and MOX is gyrase inhibition, other possible mechanisms cannot be ruled out. Being the functional moiety of cell, the proteins act as primary targets for developing drugs, diagnostics and therapeutics. In this study we have investigated the proteomic changes of Mycobacterium tuberculosis isolates induced by OFX and MOX by applying comparative proteomic approaches based on two-dinensional gel electrophoresis (2DE) along with matrix assisted laser desorption ionisation time of flight mass spectrometry (MALDI TOF/TOF-MS) and bioinformatic tools. The findings are likely to provide new understanding of OFX and MOX mechanisms that might be helpful in exploring new diagnostics and drug targets. Our study explored eleven proteins (Rv2889c, Rv2623, Rv0952, Rv1827, Rv1932, Rv0054, Rv1080c, Rv3418c, Rv3914, Rv1636 and Rv0009) that were overexpressed in the presence of drugs. Among them, Rv2623, Rv1827 and Rv1636 were identified as proteins with unknown function. InterProScan and molecular docking revealed that the conserved domain of hypothetical proteins interact with OFX and MOX which indicate a probable inhibition/modulation of the functioning of these proteins by both drugs, which might be overexpressed to overcome this effect.

M. tuberculosis ferritin (Rv3841): Potential involvement in Amikacin (AK) & Kanamycin (KM) resistance

Tuberculosis is an infectious disease, caused by one of the most successful human pathogen, Mycobacterium tuberculosis. Aminoglycosides, Amikacin (AK) & Kanamycin (KM) are commonly used to treat drug resistant tuberculosis. They target the protein synthesis machinery by interacting with several steps of translation. Several explanations have been proposed to explain the mechanism of aminoglycoside resistance but still our information is inadequate. Iron storing/interacting proteins were found to be overexpressed in aminoglycosides resistant isolates. Iron assimilation and utilization in M. tuberculosis plays a crucial role in growth, virulence and latency. To establish the relationship of ferritin with AK & KM resistance ferritin (Rv3841/bfrB) was cloned, expressed and antimicrobial drug susceptibility testing (DST) was carried out. Rv3841/bfrB gene was cloned and expressed in E. coli BL21 using pQE2 expression vector. Etest results for DST against AK & KM showed that the minimum inhibitory concentration (MIC) of ferritin recombinant cells was changed. Recombinants showed two fold changes in MIC with AK and three fold with KM E-strips. Overexpression of ferritin reflect the MIC shift which might be playing a critical role in the survival of mycobacteria by inhibiting/modulating the effects of AK & KM. String analysis also suggests that ferritin interacted with few proteins which are directly and indirectly involved in M. tuberculosis growth, Iron assimilation, virulence, resistance, stresses and latency.

Colistin Resistance and Management of Drug Resistant Infections

Colistin resistance is a globalized sensible issue because it has been considered a drug of the last-line resort to treat drug-resistant bacterial infections. The product of the mobilized colistin resistance (mcr) gene and its variants are the significant causes of colistin resistance, which is emerging due to the frequent colistin use in veterinary, and these genes circulate among the bacterial community. Apart from mcr genes, some other intrinsic genes and proteins are also involved in colistin resistance. Researchers focus on the most advanced genomics (whole genome sequencing), proteomics, and bioinformatics approaches to explore the question of colistin resistance. To combat colistin resistance, researchers developed various strategies such as the development of newer drugs, the repurposing of existing drugs, combinatorial treatment by colistin with other drugs, a nano-based approach, photodynamic therapy, a CRISPRi-based strategy, and a phage-based strategy. In this timeline review, we have discussed the development of colistin resistance and its management in developing countries.

Repurposing and Revival of the Drugs: A New Approach to Combat the Drug Resistant Tuberculosis

Emergence of drug resistant tuberculosis like multi drug resistant tuberculosis (MDR-TB), extensively drug-resistant tuberculosis (XDR-TB) and totally drug resistant tuberculosis (TDR-TB) has created a new challenge to fight against these bad bugs of Mycobacterium tuberculosis. Repurposing and revival of the drugs are the new trends/options to combat these worsen situations of tuberculosis in the antibiotics resistance era or in the situation of global emergency. Bactericidal and synergistic effect of repurposed/revived drugs along with the latest drugs bedaquiline and delamanid used in the treatment of MDR-TB, XDR-TB, and TDR-TB might be the choice for future promising combinatorial chemotherapy against these bad bugs.

M. tuberculosis Hypothetical Proteins and Proteins of Unknown Function: Hope for Exploring Novel Resistance Mechanisms as well as Future Target of Drug Resistance

Drug resistance in tuberculosis predominantly, mono-resistance, multi drug resistance, extensively drug resistance and totally drug resistance have emerged as a major problem in the chemotherapy of tuberculosis. Failures of first and second line anti-tuberculosis drugs treatment leads to emergence of resistant Mycobacterium tuberculosis. Few genes are reported as the principal targets of the resistance and apart from the primary targets many explanations have been proposed for drug resistance but still some resistance mechanisms are unknown. As proteins involved in most of the biological processes, these are potentially explored the unknown mechanism of drug resistance and attractive targets for diagnostics/future therapeutics against drug resistance. In last decade a panel of studies on expression proteomics of drug resistant M. tuberculosis isolates reported the differential expression of uncharacterized proteins and suggested these might be involved in resistance. Here we emphasize that detailed bioinformatics analysis (like molecular docking, pupylation, and proteins-proteins interaction) of these uncharacterized and hypothetical proteins might predict their interactive partners (other proteins) which are involved in various pathways of M. tuberculosis system biology and might give a clue for novel mechanism of drug resistance or future drug targets. In future these uncharacterized targets might be open the new resistance mechanism and used as potential drug targets against drug resistant tuberculosis.

Secretory Proteome Analysis of Streptomycin-Resistant Mycobacterium tuberculosis Clinical Isolates

Tuberculosis still remains one of the most fatal infectious diseases. Streptomycin (SM) is the drug of choice, especially for patients with multidrug-resistant tuberculosis or category II patients, because it targets the protein synthesis machinery by interacting with steps of translation. Several mechanisms have been proposed to explain the resistance, but our knowledge is inadequate. Secretome often plays an important role in pathogenesis and is considered an attractive reservoir for the development of novel diagnostic markers and targets. In this study, we analyze the secretory proteins of streptomycin-resistant Mycobacterium tuberculosis isolates by 2-dimensional gel electrophoresis-matrix assisted laser desorption/ionization-time-of-flight mass spectrometry and bioinformatic tools. Fifteen overexpressed proteins were identified in a resistant isolate that belonged to various categories such as virulence/detoxification/adaptation, intermediary metabolism and respiration, and conserved hypotheticals. Among them, Rv1860, Rv1980c, Rv2140c, Rv1636, and Rv1926c were proteins of an undefined role. Molecular docking of these proteins with SM showed that it binds to their conserved domains and suggests that these might neutralize/compensate the effect of the drug. The interactome also suggests that overexpressed proteins along with their interactive partner might be involved in M. tuberculosis virulence and resistance. The cumulative effect of these overexpressed proteins could involve SM resistance, and these might be used as diagnostic markers or potential drug targets.

Potential Alternative Strategy against Drug Resistant Tuberculosis: A Proteomics Prospect

Mycobacterium tuberculosis is one of the deadliest human pathogen of the tuberculosis diseases. Drug resistance leads to emergence of multidrug-resistant and extremely drug resistant strains of M. tuberculosis. Apart from principal targets of resistance, many explanations have been proposed for drug resistance but some resistance mechanisms are still unknown. Recently approved line probe assay (LPA) diagnostics for detecting the resistance to first and second line drugs are unable to diagnose the drug resistance in M. tuberculosis isolates which do not have the mutations in particular genes responsible for resistance. Proteomics and bioinformatic tools emerged as direct approaches for identification and characterization of novel proteins which are directly and indirectly involved in drug resistance that could be used as potential targets in future. In future, these novel targets might reveal new mechanism of resistance and can be used in diagnostics or as drug targets.

Protein translation machinery holds a key for transition of planktonic cells to biofilm state in Enterococcus faecalis: A proteomic approach

Enterococcus faecalis is a member of human gut microflora causing nosocomial infection involving biofilm formation. Ethyl methyl sulfonate induced mutants were analysed using crystal violet assay, SEM and CLSM microscopy which confirmed AK-E12 as biofilm efficient and AK-F6 as biofilm deficient mutants. Growth curve pattern revealed AK-E12 was fast growing whereas, AK-F6 was found slow growing mutant. 2D-Electrophorosis and MALDI-TOF analysis revealed over and underexpression of many translation-elongation associated proteins in mutants compared to wild type. Protein translation elongation factor G, translation elongation factor Tu and ribosomal subunit interface proteins were underexpressed and UTP-glucose-1-phosphate uridylyl transferase and cell division protein divIVA were overexpressed in AK-E12 as compared to wild type. In AK-F6, except 10 kDa chaperonin which was over-expressed other selected proteins were found to be suppressed. RT-PCR confirmed proteomic data except for the translation elongation factor G which showed contradictory data of proteome expression in AK-E12. Protein-protein interaction networks were constructed using STRING 10.0 which demonstrated strong connection of translation-elongation proteins with other proteins. Hence, it concludes from the data that translation elongation factors are important in transition of planktonic cells to biofilm cells in Enterococcus faecalis.

An efficient and rapid method for enrichment of lipophilic proteins from Mycobacterium tuberculosis H37Rv for two-dimensional gel electrophoresis

Lipophilic proteome profiling is crucial because they have an anticipated role in biological processes and pathogenesis of Mycobacterium tuberculosis. These lipophilic proteins might be used as potential targets for the development of newer diagnostic markers and drug targets due to their association with membranes and drugs. We developed an efficient and rapid method to enrich the lipophilic proteins extraction from M. tuberculosis H37Rv for 2DE. In the extraction of lipophilic proteins, nonionic detergent (Triton X-100) was added in sonication buffer that augmented the solubilization of the proteins at the time of sonication. Enriched whole cell lysate was subjected to direct phase separation using Triton X-114, without the need for preisolation of membranes. In this study, we report that our optimized extraction buffer increased the lipophilic proteins extraction and their improved resolution on 2D gel up to two- to threefolds (quantitatively and qualitatively) as compared to standard extraction buffer. Some proteins were identified by MALDI-TOF/MS.

Identification of factors involved in Enterococcus faecalis biofilm under quercetin stress

Enterococcus faecalis is a gram positive enteric commensal bacteria or opportunistic pathogen and its infection involves biofilm formation. Quercetin, a plant origin polyphenol was found to inhibit E. faecalis biofilm. Crystal violet assay, SEM and CLSM microscopy confirmed biofilm inhibition by quercetin. Proteomics was used to elucidate the changes occurred in bacterial cell by quercetin treatment. 2D-Electrophorosis and MALDI-TOF analysis revealed that nineteen proteins were differentially expressed in quercetin treated sample. Glycolytic pathways, protein translation-elongation pathways and protein folding pathways were under differential expression after treatment. Real Time-PCR (RT-PCR) validated the proteomic data at genomic level except for the translation elongation factor G which showed opposite data to proteomics. Protein-protein interaction networks constructed using STRING 10.0 demonstrated strong connection of translation-elongation proteins with many important proteins. The results of the comparative analysis indicate that quercetin exerts its inhibitory effect by disturbing glycolytic, protein translation-elongation and protein folding pathways. This disturbs bacterial physiology and stops transition of planktonic cells to biofilm state.

Proteomic analysis of a carbapenem-resistant Klebsiella pneumoniae strain in response to meropenem stress

OBJECTIVES

Antibiotic resistance has become a major problem in treating bacterial infections. The aim of this study was to elucidate the effects of meropenem on a blaKPC-2-harbouring multidrug-resistant clinical strain of Klebsiella pneumoniae through a proteomics approach in order to attain a deeper understanding of bacterial resistance strategies.

METHODS

Analysis was performed by two-dimensional gel electrophoresis of whole-cell extracts of bacteria exposed to a sublethal concentration of meropenem compared with the untreated control. Differentially expressed proteins were identified by matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF).

RESULTS

Based on Quantity One® software and MALDI-TOF analysis, 16 overexpressed proteins were identified in meropenem-treated bacteria. These proteins were primarily enzymes involved in defence against oxidative stress as well as glycolytic enzymes. LysM domain/BON superfamily protein was found overexpressed by >12-fold. STRING-10 was used to determine protein-protein interaction among the overexpressed proteins and to predict their functional associations. This study demonstrated that treatment with meropenem resulted in upregulation of various proteins involved in defence and repair mechanisms along with enzymes of energy metabolism.

CONCLUSIONS

These overexpressed proteins may play an important role in bacterial resistance mechanisms against carbapenems, however their role in resistance needs to be further validated. High expression of lysine M domain/BON superfamily protein may indicate its possible involvement in modulating the bacterial response to antibiotic stress, but its actual role requires more investigation. These findings may also help in the development of newer therapeutic agents or diagnostic markers against carbapenem resistance.

Cellular demolition: Proteins as molecular players of programmed cell death

Apoptosis, a well-characterized and regulated cell death programme in eukaryotes plays a fundamental role in developing or later-life periods to dispose of unwanted cells to maintain typical tissue architecture, homeostasis in a spatiotemporal manner. This silent cellular death occurs without affecting any neighboring cells/tissue and avoids triggering of immunological response. Furthermore, diminished forms of apoptosis result in cancer and autoimmune diseases, whereas unregulated apoptosis may also lead to the development of a myriad of neurodegenerative diseases. Unraveling the mechanistic events in depth will provide new insights into understanding physiological control of apoptosis, pathological consequences of abnormal apoptosis and development of novel therapeutics for diseases. Here we provide a brief overview of molecular players of programmed cell death with discussion on the role of caspases, modifications, ubiquitylation in apoptosis, removal of the apoptotic body and its relevance to diseases.

Focused review on dual inhibition of quorum sensing and efflux pumps: A potential way to combat multi drug resistant Staphylococcus aureus infections

Staphylococcus aureus is a common cause of skin infections, food poisoning and severe life-threatening infections. Methicillin-Resistant Staphylococcus aureus (MRSA) is known to cause chronic nosocomial infections by virtue of its multidrug resistance and biofilm formation mechanisms. The antimicrobial resistance owned by S. aureus is primarily due to efflux pumps and formation of microbial biofilms. These drug resistant, sessile and densely packed microbial communities possess various mechanisms including quorum sensing and drug efflux. Quorum sensing is a cooperative physiological process which is used by bacterial cells for social interaction and signal transduction in biofilm formation whereas efflux of drugs is derived by efflux pumps. Apart from their significant role in multidrug resistance, efflux pumps also contribute to transporting cell signalling molecules and due to their occurrence; we face the frightening possibility that we will enter the pre-antibiotic era soon. Compounds that modulate efflux pumps are also known as efflux pump inhibitors (EPI's) that act in a synergistic manner and potentiate the antibiotics efficacy which has been considered as a promising approach to encounter bacterial resistance. EPIs inhibit the mechanism of drug efflux s as well as transport of quorum sensing signalling molecules which are the supreme contributors of miscellaneous virulence factors. This review presents an accomplishments of the recent investigations allied to efflux pump inhibitors against S. aureus and also focus on related correspondence between quorum sensing system and efflux pump inhibitors in terms of S. aureus and MRSA biofilms that may open a new avenue for controlling MRSA infections.

Legume lectins: Potential use as a diagnostics and therapeutics against the cancer

Legume lectins are carbohydrate-binding protein and widely distributed in a variety of species of leguminous plants and have drawn increased attention toward cancer. Nowadays, the lectins have been studied for the screening of potential biomarkers which increased its importance in cancer research. Few plant lectins have been shown to destroy cancer cells, suggesting that lectins may have biological potential in cancer treatments. In this review, we present a focused outline of legume lectins in descriptive their complex anti-cancer mechanisms on the bases of their properties of recognition and interacting specifically with carbohydrates binding sites. Existing reports suggested the binding of lectins to cancerous cells with their cell surface markers speculated by histochemistry in vitro and in vivo. In this review, we illuminate the use of legume lectins as a natural source for diagnostics and therapeutics purpose against cancer.

Down-Regulation of Flagellar, Fimbriae, and Pili Proteins in Carbapenem-Resistant Klebsiella pneumoniae (NDM-4) Clinical Isolates: A Novel Linkage to Drug Resistance

The emergence and spread of carbapenem-resistant Klebsiella pneumoniae infections have worsened the current situation worldwide, in which totally drug-resistant strains (bad bugs) are becoming increasingly prominent. Bacterial biofilms enable bacteria to tolerate higher doses of antibiotics and other stresses, which may lead to the drug resistance. In the present study, we performed proteomics on the carbapenem-resistant NDM-4-producing K. pneumoniae clinical isolate under meropenem stress. Liquid chromatography coupled with mass spectrometry (LC-MS/MS) analysis revealed that 69 proteins were down-regulated (≤0.42-fold change) under meropenem exposure. Within the identified down-regulated proteome (69 proteins), we found a group of 13 proteins involved in flagellar, fimbriae, and pili formation and their related functions. Further, systems biology approaches were employed to reveal their networking pathways. We suggest that these down-regulated proteins and their interactive partners cumulatively contribute to the emergence of a biofilm-like state and the survival of bacteria under drug pressure, which could reveal novel mechanisms or pathways involved in drug resistance. These down-regulated proteins and their pathways might be used as targets for the development of novel therapeutics against antimicrobial-resistant (AMR) infections.