Inducer exclusion in Firmicutes: insights into the regulation of a carbohydrate ATP binding cassette transporter from Lactobacillus casei BL23 by the signal transducing protein P-Ser46-HPr

Co-utilization of carbon sources in microorganisms for the bioproduction of chemicals

Carbon source is crucial for the cell growth and metabolism in microorganisms, and its utilization significantly affects the synthesis efficiency of target products in microbial cell factories. Compared with a single carbon source, co-utilizing carbon sources provide an alternative approach to optimize the utilization of different carbon sources for efficient biosynthesis of many chemicals with higher titer/yield/productivity. However, the efficiency of bioproduction is significantly limited by the sequential utilization of a preferred carbon source and secondary carbon sources, attributed to carbon catabolite repression (CCR). This review aimed to introduce the mechanisms of CCR and further focus on the summary of the strategies for co-utilization of carbon sources, including alleviation of CCR, engineering of the transport and metabolism of secondary carbon sources, compulsive co-utilization in single culture, co-utilization of carbon sources via co-culture, and evolutionary approaches. The findings of representative studies with a significant improvement in the bioproduction of chemicals via the co-utilization of carbon sources were discussed in this review. It suggested that by combining rational metabolic engineering and irrational evolutionary approaches, co-utilizing carbon sources can significantly contribute to the bioproduction of chemicals.

Progress in cyclodextrins as important molecules regulating catalytic processes of glycoside hydrolases

Cyclodextrins (CDs) are important starch derivatives and commonly comprise α-, β-, and γ-CDs. Their hydrophilic surface and hydrophobic inner cavity enable regulation of enzyme catalysis through direct or indirect interactions. Clarifying interactions between CDs and enzyme is of great value for enzyme screening, mechanism exploration, regulation of catalysis, and applications. We summarize the interactions between CDs and glycoside hydrolases (GHs) according to two aspects: 1) CD as products, substrates, inhibitors and activators of enzymes, directly affecting the reaction process; 2) CDs indirectly affecting the enzymatic reaction by solubilizing substrates, relieving substrate/product inhibition, increasing recombinant enzyme production and storage stability, isolating and purifying enzymes, and serving as ligands in crystal structure to identify functional amino acid residues. Additionally, CD enzyme mimetics are developed and used as catalysts in traditional artificial enzymes as well as nanozymes, making the application of CDs no longer limited to GHs. This review concerns the regulation of GHs catalysis by CDs, and gives insights into research on interactions between enzymes and ligands.

Cervicovaginal microbiota: a promising direction for prevention and treatment in cervical cancer

Cervical cancer is a common malignancy in women, with high incidence rate and mortality. Persistent infection of high-risk human papillomavirus (HPV) is the most important risk factor for cervical cancer and precancerous lesions. Cervicovaginal microbiota (CVM) plays an essential role in the defense of HPV infections and prevention of subsequent lesions. Dominance of Lactobacillus is the key of CVM homeostasis, which can be regulated by host, exogenous and endogenous factors. Dysbiosis of CVM, including altered microbial, metabolic, and immune signatures, can contribute to persist HPV infection, leading to cervical cancer. However, there is no evidence of the causality between CVM and cervical cancer, and the underlying mechanism remains unexplored. Considering the close correlation between CVM dysbiosis and persistent HPV infection, this review will overview CVM, its role in cervical cancer development and related mechanisms, and the prospects for therapeutic applications.

An α type gluco-oligosaccharide from brown algae Laminaria japonica stimulated the growth of lactic acid bacteria encoding specific ABC transport system components

Glucan is the most widely distributed glycan. Many probiotics such as lactic acid bacteria (LAB) encoded corresponding hydrolytic enzymes, which could use these glucans as energy substances. Brown alga is rich in glucan and has high edible and medicinal value, but research on its regulation to probiotics is not detailed enough. In this study, we determined a novel neutral α type gluco-oligosaccharide from the brown alga Laminaria japonica with a degree of polymerization (DP) of 2-8 and a structure that mainly consists of α-(1→4)-linked glycosidic bonds called Laminaria japonica gluco-oligosaccharide (LJGO). Fermentation in vitro and gene-phenotype correlation analyses revealed that LJGO selectively stimulated the growth of the LAB strain encoding a specific ATP-binding cassette (ABC) transport system in a GH13 gene cluster, with apparent differences among 14 tested species. Comparative genomics further revealed that this transport system is species-specific, implying a potential contribution to species evolution. Transcriptomic analysis based on LAB strains cultured on LJGO and 1H-NMR findings of LJGO residues after strain utilization showed that the GH13 gene cluster contains functional LAB genes involved in LJGO utilization. Further verification by gene knockout studies is needed to expand our findings.

The role of vaginal microecology in the cervical cancer

AIM

To explore the role of vaginal microecology in cervical cancer, so as to increase the understanding of cervical cancer and lay a foundation for future large-sample clinical trials.

METHODS

We reviewed and summarized the literature comprehensively, and discussed the relationship between vaginal microecology and HPV infection, CIN progression and cervical cancer, as well as the potential molecular mechanism and the prospects of probiotics and prebiotics in future cancer treatments.

RESULTS

With the popularization of high-throughput sequencing technology and the development of bioinformatics analysis technology, many evidences show that the increase in the diversity of the bacterial community in the vaginal microecological environment and the decrease in the number of Lactobacilli are associated with the continuous infection of HPV and the further development of CIN, cervical cancer-related.

CONCLUSIONS

Vaginal microecological imbalance has an important impact on the occurrence and development of cervical cancer. However, the pathogenesis is not completely clear, and more high-level basic research and longitudinal clinical studies are needed to verify.

Remediation of polycyclic aromatic hydrocarbons by sulfate radical advanced oxidation: Evaluation of efficiency and ecological impact

Remediation of polycyclic aromatic hydrocarbon (PAH) contamination in soil remains expensive and difficult. Sulfate radical advanced oxidation processes (SR-AOPs) can be used for in situ PAH oxidation but their efficiency and ecological impacts require evaluation. Here, we tested the remediation efficiency and ecological impacts of an SR-AOP combining sodium persulfate and ferrous sulfate (FS), the FS SR-AOP with the chelating agent citric acid (FS+CA), and the FS SR-AOP with chelating agent and the surfactant IGEPALCA-720 (FS+CA+IG) compared with natural attenuation (control, CK). We measured PAH, soil physicochemical properties (pH, soil organic matter [SOM]), and soil biological properties (polyphenol oxidase [PPO] activity, peroxidase [POD] activity, soil microbes) in contaminated soil samples after incubation with FS, FS+CA, FA+CA+IG, or CK for 1, 15, and 30 d. Compared with CK, all SR-AOPs significantly decreased PAH after 1 d, with FS+CA+IG showing the highest efficiency (80.8%) and PAH removal peaking at 15 d. FS+CA+IG treatment reduced SOM the least and soil pH the most; after 30 d, SOM recovered to ~80% of the level observed in CK, but soil pH decreased further. PPO and POD activities were highest after 15 and 30 d of FS+CA+IG treatment. Real-time quantitative PCR demonstrated that SR-AOPs significantly decreased quantities of PAH-degrading bacteria, soil bacteria, fungi, and actinobacteria at 1 d, but after 30 d, the microbes recovered to levels similar to those observed in CK, with no significant differences among SR-AOPs. SR-AOPs reduced bacterial diversity and changed the dominant phylum from Acidobacteria to Firmicutes. In summary, SR-AOP treatment with both the chelating agent and the surfactant produced the best PAH removal and least SOM destruction but the largest pH decrease, although some factors recovered with longer incubation. This study provides key information for improving PAH remediation and evaluating its ecological impact.

The impact of carbon and nitrogen catabolite repression in microorganisms

Organisms have cellular machinery that is focused on optimum utilization of resources to maximize growth and survival depending on various environmental and developmental factors. Catabolite repression is a strategy utilized by various species of bacteria and fungi to accommodate changes in the environment such as the depletion of resources, or an abundance of less-favored nutrient sources. Catabolite repression allows for the rapid use of certain substrates like glucose over other carbon sources. Effective handling of carbon and nitrogen catabolite repression in microorganisms is crucial to outcompete others in nutrient limiting conditions. Investigations into genes and proteins linked to preferential uptake of different nutrients under various environmental conditions can aid in identifying regulatory mechanisms that are crucial for optimum growth and survival of microorganisms. The exact time and way bacteria and fungi switch their utilization of certain nutrients is of great interest for scientific, industrial, and clinical reasons. Catabolite repression is of great significance for industrial applications that rely on microorganisms for the generation of valuable bio-products. The impact catabolite repression has on virulence of pathogenic bacteria and fungi and disease progression in hosts makes it important area of interest in medical research for the prevention of diseases and developing new treatment strategies. Regulatory networks under catabolite repression exemplify the flexibility and the tremendous diversity that is found in microorganisms and provides an impetus for newer insights into these networks.

The interplay between the vaginal microbiome and innate immunity in the focus of predictive, preventive, and personalized medical approach to combat HPV-induced cervical cancer

HPVs representing the most common sexually transmitted disease are a group of carcinogenic viruses with different oncogenic potential. The immune system and the vaginal microbiome represent the modifiable and important risk factors in HPV-induced carcinogenesis. HPV infection significantly increases vaginal microbiome diversity, leading to gradual increases in the abundance of anaerobic bacteria and consequently the severity of cervical dysplasia. Delineation of the exact composition of the vaginal microbiome and immune environment before HPV acquisition, during persistent/progressive infections and after clearance, provides insights into the complex mechanisms of cervical carcinogenesis. It gives hints regarding the prediction of malignant potential. Relative high HPV prevalence in the general population is a challenge for modern and personalized diagnostics and therapeutic guidelines. Identifying the dominant microbial biomarkers of high-grade and low-grade dysplasia could help us to triage the patients with marked chances of lesion regression or progression. Any unnecessary surgical treatment of cervical dysplasia could negatively affect obstetrical outcomes and sexual life. Therefore, understanding the effect and role of microbiome-based therapies is a breaking point in the conservative management of HPV-associated precanceroses. The detailed evaluation of HPV capabilities to evade immune mechanisms from various biofluids (vaginal swabs, cervicovaginal lavage/secretions, or blood) could promote the identification of new immunological targets for novel individualized diagnostics and therapy. Qualitative and quantitative assessment of local immune and microbial environment and associated risk factors constitutes the critical background for preventive, predictive, and personalized medicine that is essential for improving state-of-the-art medical care in patients with cervical precanceroses and cervical cancer. The review article focuses on the influence and potential diagnostic and therapeutic applications of the local innate immune system and the microbial markers in HPV-related cancers in the context of 3P medicine.

Characterization of a putative maltodextrin-binding protein of Streptococcus pyogenes, SPs0871 and the development of a VHH inhibitor

Streptococcus pyogenes causes a wide range of human infections. Currently, antibiotics are the main treatment for S. pyogenes infection, but serious anti-microbial resistance requires alternative treatment options. To develop a novel strategy for treatment, we physicochemically characterized SPs0871, a putative maltose/maltodextrin-binding protein that is thought to have important roles in the pathogenesis of invasive streptococci. We obtained a variable domain of heavy chain of heavy-chain antibody, the smallest unit of an antibody, which specifically binds to SPs0871. Although the VHH completely inhibited the binding of maltodextrins to SPs0871, the inhibition did not lead to growth suppression of the bacteria. Our results provide important insights for development of VHH as an anti-streptococcal therapeutic.

Lactose-appended β-cyclodextrin as an effective nanocarrier for brain delivery

The blood-brain barrier (BBB) prevents the permeability of drugs into the brain, and as such limits the management of various brain diseases. To overcome this barrier, drug-encapsulating nanoparticles or vesicles, drug conjugates, and other types of drug delivery systems (DDSs) have been developed. However, the brain-targeting ability of nanoparticles or vesicles is still insufficient. Recently, among the various brain-targeting ligands previously studied for facilitating transcellular BBB transport, several sugar-appended nanocarriers for brain delivery were identified. Meanwhile, cyclodextrins (CyDs) have been used as nanocarriers for drug delivery since they can encapsulate hydrophobic compounds with high biocompatibility. Therefore, in this study, we created various sugar-appended β-cyclodextrins (β-CyDs) to discover novel brain-targeting ligands. As a result, of the six sugar-appended CyDs, lactose-appended β-CyD (Lac-β-CyD) showed greater cellular uptake in hCMEC/D3 cells, human brain microvascular endothelial cells, than other sugar-appended β-CyDs did. In addition, the permeability of Lac-β-CyD within the in vitro human BBB model was greater than that of other sugar-appended β-CyDs. Moreover, Lac-β-CyD significantly accumulated in the mouse brain after intravenous administration. Thus, Lac-β-CyD efficiently facilitated the accumulation of the model drug into the mouse brain. These findings suggest that Lac-β-CyD has the potential to be a novel carrier for drugs across the BBB.

Enterococcus faecalis Maltodextrin Gene Regulation by Combined Action of Maltose Gene Regulator MalR and Pleiotropic Regulator CcpA

Enterococci are Gram-positive bacteria present in the healthy human microbiota, but they are also a leading cause of nosocomial infections. Maltodextrin utilization by Enterococcus faecalis has been identified as an important factor for colonization of mammalians hosts. Here, we show that the LacI/GalR transcriptional regulator MalR, the maltose gene regulator, is also the main regulator of the operons encoding an ABC transporter (mdxEFG) and three metabolic enzymes (mmdH-gmdH-mmgT) required for the uptake and catabolism of maltotetraose and longer maltodextrins. The utilization of maltose and maltodextrins is consequently coordinated and induced by the disaccharide maltose, which binds to MalR. Carbon catabolite repression of the mdxEFG and mmdH-gmdH-mmgT operons is mediated by both P-Ser-HPr/MalR and P-Ser-HPr/CcpA. The latter complex exerts only moderate catabolite repression, which became visible when comparing maltodextrin operon expression levels of a malR ^- mutant (with a mutant allele for the malR gene) and a malR ^- ΔccpA double mutant grown in the presence of maltose, which is transported via a phosphotransferase system and, thus, favors the formation of P-Ser-HPr. Moreover, maltodextrin transport via MdxEFG slows rapidly when glucose is added, suggesting an additional regulation via inducer exclusion. This complex regulation of metabolic operons likely allows E. faecalis to fine-tune gene expression in response to changing environmental conditions.IMPORTANCE Enterococcus faecalis represents a leading cause of hospital-acquired infections worldwide. Several studies highlighted the importance of carbohydrate metabolism in the infection process of this bacterium. The genes required for maltodextrin metabolism are particularly induced during mouse infection and, therefore, should play an important role for pathogenesis. Since no data were hitherto available concerning the regulation of expression of the maltodextrin operons, we have conducted experiments to study the underlying mechanisms.

Atomic Details of Carbon-Based Nanomolecules Interacting with Proteins

Since the discovery of fullerene, carbon-based nanomolecules sparked a wealth of research across biological, medical and material sciences. Understanding the interactions of these materials with biological samples at the atomic level is crucial for improving the applications of nanomolecules and address safety aspects concerning their use in medicine. Protein crystallography provides the interface view between proteins and carbon-based nanomolecules. We review forefront structural studies of nanomolecules interacting with proteins and the mechanism underlying these interactions. We provide a systematic analysis of approaches used to select proteins interacting with carbon-based nanomolecules explored from the worldwide Protein Data Bank (wwPDB) and scientific literature. The analysis of van der Waals interactions from available data provides important aspects of interactions between proteins and nanomolecules with implications on functional consequences. Carbon-based nanomolecules modulate protein surface electrostatic and, by forming ordered clusters, could modify protein quaternary structures. Lessons learned from structural studies are exemplary and will guide new projects for bioimaging tools, tuning of intrinsically disordered proteins, and design assembly of precise hybrid materials.

Role of Lactobacillus in cervical cancer

Cervical cancer is a common malignant cancer among women worldwide. Changes in the vaginal microecological environment lead to multiple gynecological diseases, including cervical cancer. Recent research has shown that Lactobacillus may play an important role in the occurrence and development of cervical cancer. This review explores the role of Lactobacillus in cervical cancer. A total of 29 articles were included after identification and screening. The pertinent literature on Lactobacillus in cervical cancer from two perspectives, including clinical studies and experimental studies, was analyzed. An association network for the mechanism by which Lactobacillus induces cervical cancer was constructed. In addition, we provide direction and insight for further research on the role of Lactobacillus in cervical cancer.

Enzymes Required for Maltodextrin Catabolism in Enterococcus faecalis Exhibit Novel Activities

Maltose and maltodextrins are formed during the degradation of starch or glycogen. Maltodextrins are composed of a mixture of maltooligosaccharides formed by α-1,4- but also some α-1,6-linked glucosyl residues. The α-1,6-linked glucosyl residues are derived from branching points in the polysaccharides. In Enterococcus faecalis, maltotriose is mainly transported and phosphorylated by a phosphoenolpyruvate:carbohydrate phosphotransferase system. The formed maltotriose-6″-phosphate is intracellularly dephosphorylated by a specific phosphatase, MapP. In contrast, maltotetraose and longer maltooligosaccharides up to maltoheptaose are taken up without phosphorylation via the ATP binding cassette transporter MdxEFG-MsmX. We show that the maltose-producing maltodextrin hydrolase MmdH (GenBank accession no. EFT41964) in strain JH2-2 catalyzes the first catabolic step of α-1,4-linked maltooligosaccharides. The purified enzyme converts even-numbered α-1,4-linked maltooligosaccharides (maltotetraose, etc.) into maltose and odd-numbered (maltotriose, etc.) into maltose and glucose. Inactivation of mmdH therefore prevents the growth of E. faecalis on maltooligosaccharides ranging from maltotriose to maltoheptaose. Surprisingly, MmdH also functions as a maltogenic α-1,6-glucosidase, because it converts the maltotriose isomer isopanose into maltose and glucose. In addition, E. faecalis contains a glucose-producing α-1,6-specific maltodextrin hydrolase (GenBank accession no. EFT41963, renamed GmdH). This enzyme converts panose, another maltotriose isomer, into glucose and maltose. A gmdH mutant had therefore lost the capacity to grow on panose. The genes mmdH and gmdH are organized in an operon together with GenBank accession no. EFT41962 (renamed mmgT). Purified MmgT transfers glucosyl residues from one α-1,4-linked maltooligosaccharide molecule to another. For example, it catalyzes the disproportionation of maltotriose by transferring a glucosyl residue to another maltotriose molecule, thereby forming maltotetraose and maltose together with a small amount of maltopentaose.IMPORTANCE The utilization of maltodextrins by Enterococcus faecalis has been shown to increase the virulence of this nosocomial pathogen. However, little is known about how this organism catabolizes maltodextrins. We identified two enzymes involved in the metabolism of various α-1,4- and α-1,6-linked maltooligosaccharides. We found that one of them functions as a maltose-producing α-glucosidase with relaxed linkage specificity (α-1,4 and α-1,6) and exo- and endoglucosidase activities. A third enzyme, which resembles amylomaltase, exclusively transfers glucosyl residues from one maltooligosaccharide molecule to another. Similar enzymes are present in numerous other Firmicutes, such as streptococci and lactobacilli, suggesting that these organisms follow the same maltose degradation pathway as E. faecalis.