Promotion of Wound Healing and Prevention of Frostbite Injury in Rat Skin by Exopolysaccharide from the Arctic Marine Bacterium Polaribacter sp. SM1127.

Many marine microorganisms synthesize exopolysaccharides (EPSs), and some of these EPSs have been reported to have potential in different fields. However, the pharmaceutical potentials of marine EPSs are rarely reported. The EPS secreted by the Artic marine bacterium Polaribacter sp. SM1127 has good antioxidant activity, outstanding moisture-retention ability, and considerable protective property on human dermal fibroblasts (HDFs) at low temperature. Here, the effects of SM1127 EPS on skin wound healing and frostbite injury prevention were studied. Scratch wound assay showed that SM1127 EPS could stimulate the migration of HDFs. In the full-thickness cutaneous wound experiment of Sprague-Dawley (SD) rats, SM1127 EPS increased the wound healing rate and stimulated tissue repair detected by macroscopic observation and histologic examination, showing the ability of SM1127 EPS to promote skin wound healing. In the skin frostbite experiment of SD rats, pretreatment of rat skin with SM1127 EPS increased the rate of frostbite wound healing and promoted the repair of the injured skin significantly, indicating the good effect of SM1127 EPS on frostbite injury prevention. These results suggest the promising potential of SM1127 EPS in the pharmaceutical area to promote skin wound healing and prevent frostbite injury.

Deep RNA sequencing reveals a high frequency of alternative splicing events in the fungus Trichoderma longibrachiatum.

BACKGROUND: Alternative splicing is crucial for proteome diversity and functional complexity in higher organisms. However, the alternative splicing landscape in fungi is still elusive. RESULTS: The transcriptome of the filamentous fungus Trichoderma longibrachiatum was deep sequenced using Illumina Solexa technology. A total of 14305 splice junctions were discovered. Analyses of alternative splicing events revealed that the number of all alternative splicing events (10034), intron retentions (IR, 9369), alternative 5' splice sites (A5SS, 167), and alternative 3' splice sites (A3SS, 302) is 7.3, 7.4, 5.1, and 5.9-fold higher, respectively, than those observed in the fungus Aspergillus oryzae using Illumina Solexa technology. This unexpectedly high ratio of alternative splicing suggests that alternative splicing is important to the transcriptome diversity of T. longibrachiatum. Alternatively spliced introns had longer lengths, higher GC contents, and lower splice site scores than constitutive introns. Further analysis demonstrated that the isoform relative frequencies were correlated with the splice site scores of the isoforms. Moreover, comparative transcriptomics determined that most enzymes related to glycolysis and the citrate cycle and glyoxylate cycle as well as a few carbohydrate-active enzymes are transcriptionally regulated. CONCLUSIONS: This study, consisting of a comprehensive analysis of the alternative splicing landscape in the filamentous fungus T. longibrachiatum, revealed an unexpectedly high ratio of alternative splicing events and provided new insights into transcriptome diversity in fungi.

Comparative genomics provide insights into evolution of trichoderma nutrition style.

Saprotrophy on plant biomass is a recently developed nutrition strategy for Trichoderma. However, the physiology and evolution of this new nutrition strategy is still elusive. We report the deep sequencing and analysis of the genome of Trichoderma longibrachiatum, an efficient cellulase producer. The 31.7-Mb genome, smallest among the sequenced Trichoderma species, encodes fewer nutrition-related genes than saprotrophic T. reesei (Tr), including glycoside hydrolases and nonribosomal peptide synthetase-polyketide synthase. Homology and phylogenetic analyses suggest that a large number of nutrition-related genes, including GH18 chitinases, ß-1,3/1,6-glucanases, cellulolytic enzymes, and hemicellulolytic enzymes, were lost in the common ancestor of T. longibrachiatum (Tl) and Tr. dN/dS (ω) calculation indicates that all the nutrition-related genes analyzed are under purifying selection. Cellulolytic enzymes, the key enzymes for saprotrophy on plant biomass, are under stronger purifying selection pressure in Tl and Tr than in mycoparasitic species, suggesting that development of the nutrition strategy of saprotrophy on plant biomass has increased the selection pressure. In addition, aspartic proteases, serine proteases, and metalloproteases are subject to stronger purifying selection pressure in Tl and Tr, suggesting that these enzymes may also play important roles in the nutrition. This study provides insights into the physiology and evolution of the nutrition strategy of Trichoderma.

Cu-catalyzed asymmetric borylative cyclization of cyclohexadienone-containing 1,6-enynes.

The first Cu-catalyzed asymmetric borylative cyclization of cyclohexadienone-containing 1,6-enynes is achieved through a tandem process: selective ß-borylation of propargylic ether and subsequent conjugate addition to cyclohexadienone. The reaction proceeds with excellent regioselectivity and enantioselectivity to afford an optically pure cis-hydrobenzofuran framework bearing alkenylboronate and enone substructures. Furthermore, the resulting bicyclic products could be converted to bridged and tricyclic ring structures. This method extends the realm of Cu-catalyzed asymmetric tandem reactions using bis(pinacolato)diboron (B2pin2).

Gene cloning, expression and characterization of a novel xylanase from the marine bacterium, Glaciecola mesophila KMM241.

Marine xylanases are rather less studied compared to terrestrial xylanases. In this study, a new xylanase gene, xynB, was cloned from the marine bacterium, Glaciecola mesophila KMM241, and expressed in Escherichia coli. xynB encodes a multi-domain xylanase XynB of glycoside hydrolase (GH) family 8. The recombinant XynB comprises an N-terminal domain (NTD) with unknown function and a catalytic domain, which is structurally novel among the characterized xylanases of GH family 8. XynB has the highest identity (38%) to rXyn8 among the characterized xylanases. The recombinant XynB showed maximal activity at pH 6-7 and 35 °C. It is thermolabile and salt-tolerant. XynB is an endo-xylanase that demands at least five sugar moieties for effective cleavage and to hydrolyze xylohexaose and xylopentaose into xylotetraose, xylotriose and xylobiose. NTD was expressed in Escherichia coli to analyze its function. The recombinant NTD exhibited a high binding ability to insoluble xylan and avicel and little binding ability to chitosan and chitin. Since the NTD shows no obvious homology to any known carbohydrate-binding module (CBM) sequence in public databases, XynB may contain a new type of CBM.

Antimicrobial peptaibols from Trichoderma pseudokoningii induce programmed cell death in plant fungal pathogens.

Antibiosis is one of the widespread strategies used by Trichoderma spp. against plant fungal pathogens, the mechanism of which, however, remains poorly understood. Peptaibols are a large family of antimicrobial peptides produced by Trichoderma spp. Our previous study showed that trichokonins, a type of peptaibol from Trichoderma pseudokoningii SMF2, exhibited antibiotic activities against plant fungal pathogens. In this study, we first demonstrated that trichokonin VI (TK VI) induced extensive apoptotic programmed cell death in plant fungal pathogens. For a deeper insight into the apoptotic mechanism involved in the action of TK VI, Fusarium oxysporum was used as a model. Cells of F. oxysporum treated with TK VI showed apoptotic hallmarks, such as exposure of phosphatidylserine, the appearance of reactive oxygen species and fragmentation of nuclear DNA. Moreover, TK VI-treated cells exhibited an accumulation of cytoplasmic vacuoles with loss of the mitochondrial transmembrane potential, and this process was independent of metacaspases. Therefore, TK VI induces metacaspase-independent apoptotic cell death in F. oxysporum. This represents what is believed to be the first report to reveal the antibiotic mechanism of peptaibols against plant fungal pathogens.

Antimicrobial peptaibols, novel suppressors of tumor cells, targeted calcium-mediated apoptosis and autophagy in human hepatocellular carcinoma cells.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common cancers in the world which is highly chemoresistant to currently available chemotherapeutic agents. Thus, novel therapeutic targets are needed to be sought for the successful treatment of HCC. Peptaibols, a family of peptides synthesized non-ribosomally by the Trichoderma species and other fungi, exhibit antibiotic activities against bacteria and fungi. Few studies recently showed that peptaibols exerted cytotoxicity toward human lung epithelial and breast carcinoma cells. However, the mechanism involved in peptaibol-induced cell death remains poorly understood. RESULTS: Here, we showed that Trichokonin VI (TK VI), a peptaibol from Trichoderma pseudokoningii SMF2, induced growth inhibition of HCC cells in a dose-dependent manner. It did not obviously impair the viability of normal liver cells at lower concentration. Moreover, the suppression of cell viability resulted from the programmed cell death (PCD) with characteristics of apoptosis and autophagy. An influx of Ca2+ triggered the activation of mu-calpain and proceeded to the translocation of Bax to mitochondria and subsequent promotion of apoptosis. On the other hand, typically morphological characteristics consistent with autophagy were also observed by punctate distribution of MDC staining and the induction of LC3-II, including extensive autophagic vacuolization and enclosure of cell organelles by these autophagosomes. More significantly, specific depletion of Bak expression by small RNA interfering (siRNA) could partly attenuate TK VI-induced autophagy. However, siRNA against Bax led to increased autophagy. CONCLUSION: Taken together, these findings showed for the first time that peptaibols were novel regulators involved in both apoptosis and autophagy, suggesting that the class of peptaibols might serve as potential suppressors of tumor cells.

Gene cloning, expression and characterization of a new cold-active and salt-tolerant endo-beta-1,4-xylanase from marine Glaciecola mesophila KMM 241.

Although a lot of xylanases are studied, only a few xylanases from marine microorganisms have been reported. A new xylanase gene, xynA, was cloned from marine bacterium Glaciecola mesophila KMM 241. Gene xynA contains 1,272 bp and encodes a 423-amino acid xylanase precursor. The recombinant xylanase, XynA, expressed in Escherichia coli BL21 is a monomer with a molecular mass of 43 kDa. Among the characterized xylanases, XynA shares the highest identity (46%) to the xylanase from Flavobacterium sp. strain MSY2. The optimum pH and temperature for XynA is 7.0 and 30 degrees C. XynA retains 23% activity and 27% catalytic efficiency at 4 degrees C. XynA has low thermostability, remaining 20% activity after 60-min incubation at 30 degrees C. Its apparent melting temperature (T (m)) is 44.5 degrees C. These results indicate that XynA is a cold-active xylanase. XynA shows a high level of salt-tolerance, with the highest activity at 0.5 M NaCl and retaining 90% activity in 2.5 M NaCl. It may be the first salt-tolerant xylanase reported. XynA is a strict endo-beta-1,4-xylanase with a demand of at least four sugar moieties for effective cleavage. It efficiently hydrolyzes xylo-oligosaccharides and xylan into xylobiose and xylotriose without producing xylose, suggesting its potential in xylo-oligosaccharides production.

Purification and enzymatic characterization of two beta-endoxylanases from Trichoderma sp. K9301 and their actions in xylooligosaccharide production.

Trichoderma sp. K9301 secreting endoxylanases with an activity of 2836 U/g (dry weight) was screened for XOs production. Two acidic beta-endoxylanases EX1 (30.1 kDa) and EX2 (20.1 kDa) were purified from crude extract of the strain K9301 in solid fermentation. Action modes of EX1 and EX2 towards XOs showed similar hydrolysis characters to endoxylanases belonging to glycosyl hydrolase family 10 and 11, respectively. EX1 exhibited better affinity but lower hydrolytic efficiency than EX2 to xylans from beechwood, birchwood, and oat-spelt. They had synergistic action on xylan hydrolysis. The optimum condition to prepare XOs from corncobs was obtained as 10 mg/ml corncob xylan incubated with 10 U/mg crude enzymes at 50 degrees C for 3 h. The yield of XOs reached 43.3%, and only a little amount of xylose (3.1%) was simultaneously produced, suggesting the good potential of strain K9301 in XOs production.

Purification and functional characterization of endo-beta-mannanase MAN5 and its application in oligosaccharide production from konjac flour.

MAN5, the main extracellular saccharide hydrolase from Bacillus sp. MSJ-5, is an endo-beta-mannanase with a demand of at least five sugar moieties for effective cleavage. It has a pH optimum of 5.5 and a temperature optimum of 50 degrees C and is stable at pH 5-9 or below 65 degrees C. MAN5 has a very high ability to hydrolyze konjac flour, 10 U/mg of which could completely liquefy konjac flour gum in 10 min at 50 degrees C. HPLC analysis showed that most glucomannan in the konjac flour was hydrolyzed into a large amount of oligosaccharides with DP of 2-6 and a very small amount of monosaccharide. With the culture supernatant as enzyme source, the optimum condition to prepare oligosaccharides from konjac flour was obtained as 10 mg/ml konjac flour incubated with 10 U/mg enzyme at 50 degrees C for 24 h. With this condition, more than 90% polysaccharides in the konjac flour solution were hydrolyzed into oligosaccharides and a little monosaccharide (2.98% of the oligosaccharides). Konjac flour is an underutilized agricultural material with low commercial value in China. With MAN5, konjac flour can be utilized to generate high value-added oligosaccharides. The high effectiveness and cheapness of this technique indicates its potential in industry.

Novel use for the osmolyte trimethylamine N-oxide: retaining the psychrophilic characters of cold-adapted protease deseasin MCP-01 and simultaneously improving its thermostability.

The low thermostability of cold-adapted enzymes is a main barrier for their application. A simple and reliable method to improve both the stability and the activity of cold-adapted enzymes is still rare. As a protein stabilizer, the effect of trimethylamine N-oxide (TMAO) on a cold-adapted enzyme or protein has not been reported. In this study, effects of TMAO on the structure, activity, and stability of a cold-adapted protease, deseasin MCP-01, were studied. Deseasin MCP-01 is a new type of subtilase from deep-sea psychrotolerant bacterium Pseudoalteromonas sp. SM9913. Fluorescence and CD spectra showed that TMAO did not perturb the structure of MCP-01 and therefore kept the conformational flexibility of MCP-01. One molar TMAO improved the activity of MCP-01 by 174% and its catalytic efficiency (k(cat) /K(m)) by 290% at 0 degrees C. In the presence of 1 M TMAO, the thermostability (t(1/2)) of MCP-01 increased by two- to fivefold at 60 approximately 40 degrees C. Structural analysis with CD showed that 1 M TMAO could keep the structural thermostability of MCP-01 close to that of its mesophilic counterpart subtilisin Carlsberg when incubated at 40 degrees C for 1 h. Moreover, 1 M TMAO increased the melting temperature (T(m)) of MCP-01 by 10.5 degrees C. These results suggest that TMAO can be used as a perfect stabilizing agent to retain the psychrophilic characters of a cold-adapted enzyme and simultaneously improve its thermostability.

Pilot and plant scaled production of ACE inhibitory hydrolysates from Acetes chinensis and its in vivo antihypertensive effect.

The angiotensin-I-converting enzyme (ACE) inhibitory oligopeptide-enriched hydrolysates from Acetes chinensis by treatment with the protease from Bacillus sp. SM98011 were produced at pilot scale (100 L) and plant scale (1000 L). The pilot and plant scaled hydrolysate products almost had the same properties as that at laboratory scale. Spray-drying had little effect on the peptide composition and bioactivity of the hydrolysates. The plant scaled hydrolysates were used to study its blood pressure-depressing effect in vivo. It caused reduce of 18.3-38.6 mmHg of the blood pressure of spontaneously hypertensive rats in dose-dependent manner in the range of 100-1,200 mg/kg/day. Histopathologic study showed that the pathologic changes of heart and brain in SHRs got obvious alleviation after treatment of the hydrolysates.

Production of novel angiotensin I-converting enzyme inhibitory peptides by fermentation of marine shrimp Acetes chinensis with Lactobacillus fermentum SM 605.

Acetes chinensis is an underutilized shrimp species thriving in Bo Hai Gulf of China. Its hydrolysate digested with protease SM98011 has been previously shown to have high angiotensin I-converting enzyme (ACE) inhibitory activity (He et al., J Pept Sci 12:726-733, 2006). In this article, A. chinensis were fermented by Lactobacillus fermentum SM 605 and the fermented sauce presented high ACE inhibitory activity. The minimum IC(50) value (3.37 +/- 0.04 mg/mL) was achieved by response surface methodology with optimized process parameters such as fermentation time of 24.19 h, incubation temperature at 38.10 degrees C, and pH 6.12. Three ACE inhibitory peptides are purified by ultrafiltration, gel filtration, and reverse-phase high performance liquid chromatography. Identified by mass spectrometry, their amino acid sequences are Asp-Pro, Gly-Thr-Gly, and Ser-Thr, with IC(50) values of 2.15 +/- 0.02, 5.54 +/- 0.09, and 4.03 +/- 0.10 microM, respectively. Also, they are all novel ACE inhibitory peptides. Compared with protease digestion, fermentation is a simpler and cheaper method to produce ACE inhibitory peptides from shrimp A. chinensis.

Solid-state fermentation for Trichokonins production from Trichoderma koningii SMF2 and preparative purification of Trichokonin VI by a simple protocol.

Trichokonins are peptaibols produced by Trichoderma koningii SMF2. The main isoforms are Trichokonin VI, Trichokonin VII and Trichokonin VIII. The solid-state fermentation (SSF) was applied for the production of Trichokonin VI. The fermentation factors, which included inoculum size, incubation temperature, initial moisture content and initial pH, were investigated and optimized by response surface methodology. The maximum Trichokonin VI production (4.07mg/g dry substrate) was achieved by employing inoculum size of 18%, incubation temperature at 24.3 degrees C, initial moisture content of 77.5% and initial pH at 5.0. Furthermore, gel filtration and preparative HPLC were used for separation of Trichokonin VI from a crude extract of the T. koningii SMF2 culture. With this preparative purification protocol under optimized fermentation conditions, 146.20mg Trichokonin VI was obtained from 1kg solid cultures. It has been shown that the obtained Trichokonin VI is more than 95% in purity. This is the first report on optimization of peptaibols production in SSF with high content. An efficient method for the preparative purification of Trichokonin VI is also proposed.

Autolysis of a novel multidomain subtilase-cold-adapted deseasin MCP-01 is pH-dependent and the surface loops in its catalytic domain, the linker, and the P_proprotein domain are susceptible to proteolytic attack.

Cold-adapted deseasin MCP-01 is a novel type subtilase with a multidomain structure containing a catalytic domain, a linker, a P_proprotein domain, and a PKD domain. Its autolysis was pH-dependent due to its flexible structure. N-terminal sequence analysis of the autolytic peptides revealed four autolytic sites in the catalytic domain. Three of these are in the same loops as mesophilic subtilases and one is unlike anything previously reported. Two autolytic sites were deduced in its linker and three in its P_proprotein domain, indicating the linker and the P_proprotein domain are flexible and susceptible to proteolytic attacks. Therefore, during MCP-01 autolysis, the linker and the P_proprotein domain of MCP-01 were easily attacked by proteolysis, resulting in cleavage of the C-terminal region. At the same time, some autolytic sites in the surface loops of the catalytic domain were cleaved. This is the first report describing the autolytic mechanism of a multidomain subtilase.

High throughput and rapid screening of marine protein hydrolysates enriched in peptides with angiotensin-I-converting enzyme inhibitory activity by capillary electrophoresis.

Twelve kinds of marine protein materials, including fish, shrimp, seashell, algae and seafood wastes were selected for the hydrolysis using four different proteases. The IC(50) values for angiotensin-converting enzyme (ACE) inhibitory activity of 48 hydrolysates were rapidly determined by capillary electrophoresis (CE). The values ranged from 0.17 to 501.7mg/ml, and were affected by both the marine protein resources and the selected proteases. Hydrolysates of the lowest IC(50) values were from shrimp (Acetes chinensis), shark meat, mackerel bone, Polysiphonia urceolata and Spirulina platensis, indicating these five kinds of marine food proteins contained beneficial materials for the production of ACE inhibitory peptides by proteolysis. The hydrolysates obtained using proteases Protamex and SM98011 had lower IC(50) values, showing these two proteases were superior to others. The CE method achieved the same sensitivity as the high performance liquid chromatography (HPLC) method. However, the CE method was faster and, as a result, more economical. Therefore, CE had potential for rapid screening of marine protein hydrolysates enriched in ACE inhibitory peptides.

Total synthesis of phorboxazole B.

An efficient and highly convergent total synthesis of the potent antitumor agent phorboxazole B has been achieved. The synthetic strategy of this synthesis features: 1) a highly efficient substrate-controlled hydrogenation to construct the functionalized cis-tetrahydropyrane unit; 2) iterative crotyl addition to synthesize the segment that contains alternating hydroxyl and methyl substituents; 3) Hg(OAc)2/I2-induced cyclization to establish the cis-tetrahydropyrane moiety; 4) 1,3-asymmetric induction in the Mukaiyama aldol reaction to afford the stereogenic centers at C9 and C3; and 5) the exploration of the Still-Gennari olefination reaction to complete the macrolide ring of phorboxazoloe B.

A novel approach to estimate in vitro antibacterial potency of Chinese medicine using a concentration-killing curve method.

The antibacterial pharmacodynamics against E. coli of Chinese medicine (CM) Rhizoma coptidis (Coptis Root) and its formula Sanhuang, and the control antibiotics enoxacin, were analyzed by a concentration-killing curve (CKC) approach, and the novel parameters BC50 and r for antibacterial potency were proposed. Using the agar plate method, about 400 cells of E. coli were evenly inoculated into LB agar plates containing a series of different concentrations of CM or antibiotic, and after a 24 hour incubation at 37 degrees C, all the viable colonies were enumerated. This resulted in a sigmoid concentration-killing curve , in which No, that could be closely fitted (R2 > 0.9) with the function: N = 1 + e(r(x-BC50))/N0 in which N0, BC50 and r represent meaningfully inoculums size, median bactericidal concentration, and bactericidal intensity, respectively. N modeled the survival of colony-forming units on each plate (CFU/plate) in a concentration series x of the drug. The CKC was symmetrical about its single inflexion (BC50, N0/2). Therefore theoretically, 2BC50 can replace MBC (minimum bactericidal concentration). BC1 = BC50 + r/ln(N0-1), the drug concentration at r which only one colony survived, was the least critical value of MBC in CKC. The parameters 2BC50 and BC1 agreed more closely with the definition of MBC, and were little affected by either the biochemical basis of the antibacterial or the inoculum's size (200-400 CFU/plate), and were determined by a multi-point curve. As a result, these were more accurate, reproducible and practical as metrics than was the endpoint of MBC. The two-dimensional CKC, involving BC50 and r, captures the intrinsic dynamics of the antibacterial effect of CM/strain versus concentration, and it is consistent with the Logistic equation of the bacterial growth curve in the format. This verified approach has considerable value as a tool for the accurate and proper administration of CM. The CKC of CM, different from that of antibiotics, is likely to be the resultant force of each ingredient in certain CM, which provides a clue to solve the problem of antibiotic resistance.

Toward the total synthesis of phorboxazole B: an efficient synthesis of the C20-C46 segment.

An efficient synthesis of the C20-C46 segment of phorboxazole B is described. The key steps involved Hg(OAc)(2)/I(2)-induced cyclization to construct the cis-tetrahydropyran moiety, the coupling of the metalated 2-methyloxazole 7 with lactone 6, and Julia olefination to furnish the conjugated diene moiety.

Dissecting and exploiting nonribosomal peptide synthetases.

A large number of therapeutically useful cyclic and linear peptides of bacteria or fungal origin are synthesized via a template-directed, nucleic-acid-independent nonribosomal mechanism. This process is carried out by mega-enzymes called nonribosomal peptide synthetases (NRPSs). NRPSs contain repeated coordinated groups of active sites called modules, and each module is composed of several domains with different catalytic activities. The familiarity to these domains lays base for the future genetic engineering of NRPSs to generate entirely "unnature" products. The details about NRPSs domain structures and the exploitation of NRPSs are described in this review.