Regulation of Mycobacterium biofilm development and novel measures against antibiotics resistance.

Currently, there are over 170 recognized species of Mycobacterium, the only genus in the family Mycobacteriaceae. Organisms belonging to this genus are quite diverse with respect to their ability to cause disease in humans. The Mycobacterium genus includes human pathogens (Mycobacterium tuberculosis complex and Mycobacterium leprae) and environmental microorganisms known as non-tuberculosis mycobacteria (NTM). A common pathogenic factor of Mycobacterium is the formation of biofilms. Bacterial biofilms are usually defined as bacterial communities attached to the surface, and are also considered as shared spaces of encapsulated microbial cells, including various extracellular polymeric substrates (EPS), such as polysaccharides, proteins, amyloid proteins, lipids, and extracellular DNA (EDNA), as well as membrane vesicles and humic like microorganisms derived refractory substances. The assembly and dynamics of the matrix are mainly coordinated by second messengers, signaling molecules, or small RNAs. Fully deciphering how bacteria provide structure for the matrix, thereby promoting extracellular reactions and benefiting from them, remains a challenge for future biofilm research. This review introduces a five step development model for biofilms and a new model for biofilm formation, analyses the pathogenicity of biofilms, their interactions with bacteriophages and host immune cells, and the key genes and regulatory networks of mycobacterial biofilms, as well as mycobacterial biofilms and drug resistance, in order to provide a basis for clinical treatment of diseases caused by biofilms.

The biotin synthesis pathway in Mycobacteria tuberculosis is a new target for the development of anti-tuberculosis drugs / 药学学报

italic>Mycobacterium tuberculosis, responsible for tuberculosis (TB), remains a major health problem worldwide and is one of the infectious diseases causing increased morbidity and mortality worldwide. Biotin, namely vitamin H, is an important cofactor necessary for fatty acid biosynthesis, gluconeogenesis and amino acid metabolism in organisms including Mycobacterium tuberculosis. Due to its inability to ingestion biotin from outside, Mycobacterium tuberculosis can only obtain biotin through biotin biosynthesis. Different from the classical BioC-BioH, BioI-BioW and non-classical BioZ pathways, Mycobacterium tuberculosis synthesized biotin by "BioC-BioH(2)" pathway in the early stage. This review focuses on the unique biotin synthesis pathway of Mycobacterium tuberculosis and its key genes, especially the response of this pathway and biotin-dependent carboxylase to tuberculosis first-and second-line drugs, as well as inhibitors and natural products targeting biotin synthesis.

USP18-mediated protein deISGylation and its role in tuberculosis and other infectious diseases.

The transcription of interferon-stimulated gene 15 (isg15) is induced by type I interferons. ISG15 can covalently modify target proteins through the sequential action of enzymesE1, E2, and E3, a process known as ISGylation. The ISGylation of host proteins is widely involved in immune responses, such as host antiviral defence. Ubiquitin-specific protease 18 (USP18), as a deubiquitinase (DUB), can remove ISG15 conjugated to target proteins and inhibit host immune responses by suppressing the type I interferon signaling. The dynamic balance between ISGylation and deISGylation mediated by ISG15 or USP18 respectively plays a significant role in the tuberculosis. Furthermore, similar to ISG15, USP18 is extensively involved in virus-host interaction. In this review, we summarize the roles of ISGylation and deISGylation in tuberculosis and other important diseases mediated by ISG15 and USP18 respectively, underlying regulator network. Further studies in this aspect will inspire new host-targeted strategies to control important diseases such as tuberculosis.

Progress on the function of Mycobacterium T7SS (ESX) secretion system.

Mycobacterium infection can affect the host's immune function by secreting extracellular effector proteins. ESX (or type VII) system plays an important role in the secretion of effector proteins. ESX system is the protein export system in mycobacteria and many actinomycetes. However, how ESX system secretes and underlying mechanism of action remain unclear. In this review, we introduce the components, function, classification of ESX system and the process of substrates transfer to the peripheral space via this system, and discuss the roles of ESX system in antibiotics resistance, persistence, host-phage interaction, new drug targets. We hope to provide insights into the discovery of new drugs and vaccine antigens for tuberculosis.

Progress on the non-canonical mismatch repair in Mycobacterium and its role in antibiotic resistance.

Mismatch repair (MMR) is a common repair system after DNA replication, which is critical for maintaining genomic stability. Members of the MutS and MutL protein families are involved in key steps of mismatch repair. Despite the major importance of this repair pathway, MutS-MutL are absent in almost all Actinobacteria and many Archaea. Mycobacteria and others have another non-canonical MMR pathway, in which EndoMS/NucS plays a key role and has no structural homology compared to canonical MMR proteins (MutS/MutL). EndoMS/NucS mediated non-canonical mismatch repair plays an important role in DNA repair, mutation, homologous recombination and antibiotic resistance of Mycobacterium. By comparing the classical and non-canonical MMR pathways, this paper reviews the EndoMS/NucS-mediated non-canonical MMR pathway in Mycobacterium and its recent progress. We hope to bring new insights into the molecular mechanism of mycobacterial mismatch repair as well as to provide new research clues for mycobacterial antibiotic therapy.

Synthesis and biological activities of three-molecule conjugates with para-aminosalicylic acid as parent nucleus / 药学学报

Based on the idea of multi-target drug design, taking p-aminosalicylic acid (PAS) as the parent nucleus, the unreported target molecules TM1 and TM2 were designed with PAS, isonicotinic acid and fluoroquinolone as three structural units conjugated by different linkers. Sixteen target molecules were synthesized by multi-step reaction, and their activities against Mycobacterium tuberculosis and human pathogenic bacteria were evaluated. The results showed that the anti-tuberculosis activity of TM2a was stronger than those of the assayed fluoroquinolones, while TM1a was comparable to that of clinafloxacin, the most active compound of the positive control fluoroquinolones; TM1a showed the strongest inhibitory activity to all almost tested strains, TM1b and TM2a showed very strong inhibitory activity to most strains, and TM1h/2h had strong inhibitory activity to some strains; The inhibitory activities of TM1a/1h on Staphylococcus aureus ATCC14125 are much stronger than those of fluoroquinolones, which eminently deserves further study. The hemolysis test results showed that the highly active molecules TM1a and TM2a exhibited relative safety below the concentrations of 8 and 32 μg·mL-1, respectively. In this study, a new hybrid molecule of three molecular pharmacophores with PAS as the parent nucleus was synthesized for the first time, and some of which have highly strong antibacterial activity, which provides a new idea for the research and development of antibiotics.

The roles of sphingosine-1-phosphate and its receptor in Mycobacterium tuberculosis infection and novel antibiotics discovery / 药学学报

Tuberculosis (TB) caused by Mycobacterium tuberculosis (M. tuberculosis) infection remains a major public health problem of global concern, largely due to antibiotics resistance, persistence and immune evasion. Sphingolipid bioactive molecules are involved in several important pathophysiological processes. Sphingosine-1-phosphate is a key product of sphingolipid metabolism, and can play a role in two manners: autocrine and/or paracrine. Sphingosine-1-phosphate regulates T cells and a variety of antigen-presenting cells during M. tuberculosis infection, promotes antigen processing and expression in monocytes, is involved in the maturation of phagolysosome, regulates Ca2+ homeostasis, participates in the autophagy of macrophages, inhibits the survival and proliferation of M. tuberculosis within host cells, and effectively reduces the necrosis of the mouse lungs infected by M. tuberculosis. Injection of 20 nmol per mouse sphingosine-1-phosphate inhibited up to 47% of mycobacterial growth in the lung and spleen of mice infected by M. tuberculosis. In this paper, sphingosine-1-phosphate, its receptors and regulatory network were reviewed, and the specific mechanism of sphingosine-1-phosphate inhibiting the survival of M. tuberculosis-infected host cells was elaborated. This will provide novel insights into the new targets for tuberculosis prevention and treatment.

Novel antifungal agents against cryptococcal infections / 药学学报

Cryptococcal meningitis, caused by fungus Cryptococcus neoformans, is responsible for over a million infections and 600 000 deaths annually. Largely due to the limited treatment options and the intrinsic drawbacks coupled with drug resistance to current therapies, it is urgent to discover novel antifungal agents against cryptococcosis. An ideal antifungal drug should at least satisfy the following criteria: fungicidal, fungus-specific, permeable for the host barriers such as cell membranes of phagocytes and the blood-CNS barrier. Both discovery of candidates with novel mode of action and repurposing existing molecules with potent anti-cryptococcal activity are effective ways in discovery of new anti-cryptococcal agents. Here, we summarized recent advances in the study of anti-fungal activities, mechanisms of action, and clinical developments of new anti-cryptococcal drugs.

Regulatory mechanism underlying pathogen biofilm formation and potential drug targets / 药学学报

Bacterial communities usually develop biofilms abound in nature niche. The development of biofilm is a highly dynamic and complex process coordinated by multiple mechanisms, of which two-component system and quorum sensing are two well-defined systems. Biofilm is involved in the virulence of many pathogens. Therefore, targeting the key factors involved in the biofilm formation represents a novel and promising avenue for developing better antibiotics.

The progress of nanomedicine inspired by bacteriophage / 药学学报

Nanomedicine offers great promise for early diagnosis and treatment of formidable diseases. The unique morphology and biology characteristics of bacteriophage provide unprecedented opportunity for such endeavor. The paper summarizes the application of bacteriophage in nanobiomaterials, nanomedicine, nanomedicine delivery and nanodiagnosis, especially the nano-imaging reagents and future direction concerning nanomedicine based on bacteriophage.

The molecular physiological and genetic mechanisms underlying the superb efficacy of quinolones / 药学学报

The fluoroquinolones are the most widely used broad-spectrum antibiotics, accounting for 18% of global antibacterial market share. They can kill bacteria rapidly with variety of derivatives available. Different quinolones vary significantly in rate and spectrum of killing, oxygen requirement for metabolism and reliance upon protein synthesis. Further understanding the sophisticated mechanisms of action of this important antibiotic family based on the molecular genetic response of bacteria can facilitate the discovery of better quinolone derivatives. Factors such as SOS response, bacterial toxin-antitoxin system, programmed death, chromosome fragmentation and reactive oxygen have been implicated in the action to some extent. "Two steps characteristic" of quinolones killing is also emphasized, which might inspire future better quinolones modification.

Novel inhibitors against the bacterial signal peptidase I / 药学学报

New antibiotics with novel modes of action and structures are urgently needed to combat the emergence of multidrug-resistant bacteria. Bacterial signal peptidase I (SPase I) is an indispensable enzyme responsible for cleaving the signal peptide of preprotein to release the matured proteins. Increasing evidence suggests that SPase I plays a crucial role in bacterial pathogenesis by regulating the excretion of a variety of virulent factors, maturation of quorum sensing factor and the intrinsic resistance against beta-lactams. Recently, breakthrough has been achieved in the understanding of three-dimensional structure of SPase I as well as the mechanism of enzyme-inhibitors interaction. Three families of inhibitors are identified, i.e. signal peptide derivatives, beta-lactams and arylomycins. In this article, we summarize the recent advance in the study of structure, activity and structure-activity relationship of SPase I inhibitors.

Advances in the study of Mycobacterium tuberculosis protein phosphatase and its inhibitors / 药学学报

Reversible protein phosphorylation regulates multiple biochemical events. Mycobacterium tuberculosis phosphatases play important roles in regulating the pathogen physiology and interference of host signaling. They are also involved in the evasion of host immune response and blockage of the phagosome-lysosome fusion. Selective inhibition of phosphatase represents an ideal new avenue of anti-tuberculosis drug design. In this paper, we update the progresses about the regulation network of Mycobacterium tuberculosis phosphatases including MptpA, MptpB, MstP, SapM and their inhibitors. These serve as the basis for further antituberculosis drug target.

Comparison study of HBV-P mutation detection by MALDI-TOF Ms and direct PCR sequencing / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To compare the sensitivities of MALDI-TOF MS and direct PCR sequencing on gene mutations detection of hepatitis B virus.</p><p><b>METHODS</b>100 serum samples from chronic hepatitis B patients were collected, which consisted of 90 serum samples (study group) from 90 chronic hepatitis B patients received nucleoside analogues (NA) therapy for more than 1 year and HBV DNA titer still higher than 500 copies/ml and 10 serum samples (blank group) from 10 chronic hepatitis B patients never treated with antiviral therapy and HBV-DNA titer higher than 1 x 10(5) copies/ml. 9 known mutations associated with HBV P gene in these samples were detected by MALDI-TOF MS and direct PCR sequencing at the same time, TYPE4.0 software and Sequence Navigator software were used to analyze the results separately.</p><p><b>RESULTS</b>(1) In study group, mutations were detected in 53 samples and the total mutation sites were 86 by MALDI-TOF MS with a positive detection rate of 58.89%, whereas only 19 samples were found with mutations and totally 28 mutation sites were detected by direct PCR sequencing, the positive detection rate was 21.11%. The positive detection rate by MALDI-TOF MS was higher than that by direct PCR sequencing and the difference was statistically significant (P < 0.05). In blank group, no mutations were detected by any method. (2) In study group, when the HBV DNA titers were at 500-1000 copies/ml, 10(3)-10(4) copies/ml and 10(4)-10(5) copies/ml, the positive mutation detection rates by MALDI-TOF MS were 50%, 52.08% and 77.27% respectively, higher than that by direct PCR sequencing, which were only 0%, 8.33% and 45.45%. The difference was still statistically significant (P < 0.05).</p><p><b>CONCLUSIONS</b>MALDI-TOF MS had higher detection sensitivity for known mutation sites as compared to direct PCR sequencing method.</p>

Roles of PE_PGRS family in Mycobacterium tuberculosis pathogenesis and novel measures against tuberculosis.

Tuberculosis remains a serious threat to global public health. As one of the most successful pathogens, Mycobacterium tuberculosis is an adept in evasion the host immune response. M. tuberculosis PE_PGRS family has been widely proposed as molecular mantra to deflect host immunity. The feature of this family is the conserved N-terminal and variable C-terminal. PE_PGRS proteins, with functions largely unknown, are only found among mycobacteria and located in the mycobacterial cell wall and cell membrane. Most PE_PGRS proteins have antigenicity. Polymorphic PGRS domain might play a role in neutralize immune response. Several members of PE_PGRS family have been heterologously expressed for further function characterization. PE_PGRS gene expressing stage-specifically, especially during M. tuberculosis persistence, is promising intervention target to prevent reactivation. The origin, physiological role and spatiotemporal regulation feature of this family remain elusive. The understanding of these questions will shed light on the pathogenesis of M. tuberculosis and facilitate the discovery of new effective antibacterial intervention.

Advances in the study of the microbial efflux pumps and its inhibitors development / 药学学报

Drug resistant bacteria is an increasingly urgent challenge to public health. Bacteria adaptation and extensive abuse of antibiotics contribute to this dilemma. Active efflux of antibiotics is employed by the bacteria to survive the antibiotic pressure. Efflux pump is one of the hot spots of current drug related studies and ideal targets for the improvement of treatment. The efflux pumps and related mechanisms of action, regulation of expression and methodologies were summarized. Comparative genomics analyses were employed to elucidate the underlying mechanisms of action and evolution of efflux pump as exemplified by the Mycobacterium in our lab, which is a crucial re-emerging threat to global public health. The pathway and state-of-art drug development of efflux pump related drugs are included too.

Action and resistance mechanisms of capreomycin: a functional genomic perspective / 药学学报

Last two decades have witnessed the resurging of tuberculosis (TB) and multi-drug resistant TB, even the extensive drug resistant TB. It is urgent to develop novel drug to combat the increasingly worsen TB. Capreomycin is an ideal second-line TB drug. It is also recognized as an attractive template to develop more peptide antibiotics. In this review, the biosynthesis gene cluster of capreomycin, the action mechanism unveiled by transcriptome and novel resistance rational are summarized from the recent functional genomic investigation.

Estrogen receptor gene polymorphisms and HBV-induced liver cirrhosis / 中南大学学报(医学版)

OBJECTIVE@#To investigate the relationship between estrogen receptor (ER) gene polymorphisms and HBV-induced cirrhosis.@*METHODS@#Xba I and Pvu II polymorphisms of ER gene were analyzed in 98 patients with HBV-induced cirrhosis, 72 patients with chronic hepatitis B, and 84 healthy controls by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique.@*RESULTS@#The frequencies of Pp genotype and P allele of ER gene in patients with HBV-induced cirrhosis were higher than those in patients with chronic hepatitis B and controls, while the frequencies of pp genotype and p allele of ER gene in patients with HBV-induced cirrhosis were lower than those in patients with chronic hepatitis B and controls (P 0.05).@*CONCLUSION@#Pp genotype and P allele might be the susceptibility gene for HBV-induced cirrhosis while pp genotype and p allele might be the protective gene.

Research on Isolating Bacteria by Using Magnetophoresis / 中国生物工程杂志

There are similarities between magnetotactic bacteria and Acidithiobacillus ferrooxidans (A. ferrooxidans) which isolated from Acid mine drainage(AMD). The weak magnetotaxis of some bioleaching bacteria isolated were found by microscope. A magnetophoresis apparatus was designed based on these weak magnetotaxis and be used to analysis the movement of these strains. The physiological properties of the anear magnetic field strain and removed magnetic field strain which isolated successfully by magnetophoresis apparatus have large difference. The nanometer magnetic particles was extract from the Acidithiobacillus ferrooxidans which purified by spread plate method from AMFS and its main elements are Fe and O by energy spectrum analysis. The results show that A. ferrooxidans have weak magnetotaxis and can be isolated by magnetophoresis. With the development of this new isolating method, the research of magnetotactic bacteria and bioleaching will get more benefit from it.

Phylogenetic analysis of enterovirus 71 isolated from patients with hand, foot and mouth disease in Guangdong and Fujian provinces, 2000-2001 / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To identify enterovirus 71 (EV71) strains isolated from patients with hand, foot and mouth disease (HFMD) in Guangdong and Fujian provinces from 2000 to 2001 by using phylogenetic analysis.</p><p><b>METHODS</b>All 25 samples were first tested for enteric viruses by RT-PCR using enterovirus specific primers EV-1 and EV-2, and then were identified for EV71 by RT-PCR using EV71 specific primers 159S and 162A. The amplicons of 485bp segment (part of the VP1 gene) were cloned into pGEM-T and sequenced. A phylogenetic tree was constructed by comparison of the sequences with other 12 EV71 strains isolated from China, Japan, Hungary, and the United States including the prototype BrCr.</p><p><b>RESULTS</b>The positive rate of EV71 was about 20%. The sequence analysis showed that the new isolate (GZH2000) shared 94%-96% nucleotide identity with three strains isolated in 1998 and 2000, and 91% with a strain isolated in 1987 from Chinese mainland, but shared only 82%-84% homology with EV71 isolates studied abroad.</p><p><b>CONCLUSIONS</b>EV71 is one of the important pathogens of HFMD in south China. The strains isolated from mainland were closely related with most isolates from Taiwan, but different from most EV71 strains reported abroad. The symptoms of EV71 infection in mainland were not as intensive as those described in Taiwan's outbreak.</p>