Biomedical subjects

Wenli Li

Publications and source records attributed to Wenli Li.

11 recordsLinked to original sources

PubMed2006

RNA interference of Hemolin causes depletion of phenoloxidase activity in Hyalophora cecropia.

Melanization is regulated by the prophenoloxidase cascade and functions as a response to intruding microorganisms in invertebrates. When injecting dsRNA of the lepidopteran immune protein hemolin in pupae of Hyalophora cecropia (Lepidoptera: Saturniidae), we observed a significant reduction in phenoloxidase activity after 24 h, but not after 72 h. The link between hemolin and the prophenoloxidase system suggests that hemolin is a pattern recognition protein important for the triggering of the prophenoloxidase cascade in the defence against bacterial infections.

Animals↗

PubMed2006

The bifunctional glyceryl transferase/phosphatase OzmB belonging to the HAD superfamily that diverts 1,3-bisphosphoglycerate into polyketide biosynthesis.

The HAD superfamily protein OzmB from the oxazolomycin biosynthetic pathway is shown to divert the primary metabolite 1,3-diphosphoglycerate into the polyketide biosynthetic pathway as glycerate via loading of a carrier protein. Each of the steps-activation of d-3-phosphoglycerate, dephosphorylation while attached to a cysteine on OzmB, and subsequent transfer of glycerate to the phosphopantetheinyl thiol of an acyl carrier protein-was monitored by nanospray Fourier transform mass spectrometry. This activation of phosphoglycerate represents a general mechanism of diverting glycolytic metabolites into glyceryl-derived polyketides.

Amino Acid Sequence↗

PubMed2006

Utilization of the methoxymalonyl-acyl carrier protein biosynthesis locus for cloning of the tautomycin biosynthetic gene cluster from Streptomyces spiroverticillatus.

Tautomycin (TTM), a potent protein phosphatase inhibitor, consists of a polyketide chain containing a spiroketal moiety and an acyl chain bearing a dialkylmaleic anhydride structure. PCR using degenerate primers was used to clone genes from Streptomyces spiroverticillatus for formation of the methoxymalonyl-acyl carrier protein. This locus was found to contain five genes (ttmC, ttmA, ttmD, ttmB, and ttmE), one of which was used as a probe to clone the 110-kb TTM biosynthetic gene cluster. The involvement of the ttmA gene in TTM biosynthesis was confirmed by gene inactivation and mutation complementation experiments.

Acyl Carrier Protein↗

PubMed2005

Cloning, expression and phylogenetic analysis of Hemolin, from the Chinese oak silkmoth, Antheraea pernyi.

The Chinese oak silk moth Antheraea pernyi is an important silk producer. To understand microbial resistance of this moth, we cloned Hemolin, encoding a multifunctional immune protein belonging to the immunoglobulin superfamily, and examined the expression in gonads and fat body. The ApHemolin amino acid sequence was compared to other Hemolin sequences in order to predict functional sites. Several sites were conserved; among them a phosphate binding site, which according to 3D structure modelling does not appear in neuroglian, the phylogenetically closest related protein. In addition, two conserved KDG sequences in the C-C' loop of immunoglobulin domains 1 and 3, give rise to gamma-turns, which is a common motif in the C'-C'' loop of the hypervariable region L2 in vertebrate immunoglobulins. The comparisons also show variable regions of specific interest for future studies of hemolin and its interaction with microbial entities.

Amino Acid Motifs↗

PubMed2005

Improvement of nikkomycin production by enhanced copy of sanU and sanV in Streptomyces ansochromogenes and characterization of a novel glutamate mutase encoded by sanU and sanV.

Previous studies revealed that two genes-sanU and sanV were associated with nikkomycin biosynthesis in Streptomyces ansochromogenes. A plasmid used to increase an extra copy of sanU and sanV was constructed and introduced into wild-type strain. HPLC results showed that nikkomycin production of recombinant strain was about 1.8 fold than that of wild-type strain. RT-PCR analysis indicated that the transcriptional level of sanU and sanV in this recombinant strain was about two folds than that of wild-type strain. The sanU and sanV were expressed in E. coli BL21 (DE3). SanU and SanV were purified individually. SanU and SanV assembled with coenzyme B12 to form a complete enzyme in vitro, which showed glutamate mutase activity. The glutamate mutase converted L-glutamate toL-threo-beta-Methylaspartic acid, and then l-threo-beta-Methylaspartic acid was probably deaminated to form 2-oxo-3-methylsuccinic acid to join biosynthetic pathway of the peptidyl moiety HPHT in S. ansochromogenes. SanU is the coenzyme B12-binding component and more than two folds of SanU are required for maximal enzyme activity. The optimal pH and temperature for the formed enzyme are 7.5-8.5 and 35-42 degrees C, respectively. Sulfhydryl compounds are important for activity of the reassembled enzyme.

Aminoglycosides↗

PubMed2004

Silver-109 NMR spectroscopy of inorganic solids.

In this study the (109)Ag NMR spectra of the following solid inorganic silver-containing compounds were investigated: AgNO(3), AgNO(2), Ag(2)SO(4), Ag(2)SO(3), AgCO(3), Ag(3)PO(4), AgCl, AgBr, AgI, AgSO(3)CH(3), silver p-toluenesulfonate, NaAg(CN)(2), KAg(CN)(2), K(3)Ag(CN)(4), Me(4)NAgCl(2), silver diethylthiocarbamate, silver lactate, silver acetate, silver citrate, and bis[(N,N(1)-di-tert-butylformamidinato)silver(I)]. The magic angle spinning (MAS) spectra of all compounds were obtained. In some cases, when protons were available, the (1)H to (109)Ag cross-polarization (CP) technique was used to enhance the signal and shorten the experimental relaxation delay. It was possible to obtain slow MAS (or CP/MAS) or nonspinning spectra for 10 samples, allowing the determination of the principal components of the (109)Ag chemical shift (CS) tensors. The isotropic chemical shifts and the CS tensors are discussed in light of the available crystal structures. The need for an accepted standard for referencing (109)Ag chemical shifts and the use of AgSO(3)CH(3) as a CP setup sample are also discussed.

Isotopes↗

PubMed2003

The expression of GFP under the control of fibroin promotor in primary ovarian cells of Antheraea pernyi.

The fibroin promoter can stably express foreign gene in lepidopteran cells. Total RNA was extracted from the gland of silkworm, Antheraea pernyi and the transcription initiation site of fibroin gene of A. pernyi was identified by RNA ligase mediated rapid amplification of cDNA ends (RLM-RACE). The expression vector (pGFP-N2/Fib) was constructed by use of replacing the CMV promoter with the fibroin promoter. The results of visual screening under a fluorescent inverted microscope and Western blot analysis indicated that the GFP gene was expressed in the primary cells of ovary origins from A. pernyi.

Animals↗

PubMed2003

Structure and Function of sanV: a gene involved in nikkomycin biosynthesis of Streptomyces ansochromogenes.

A 6.3-kb BamHI- BglII DNA fragment was cloned from cos20 by using chromosome walking strategy. It was partially sequenced with the result that there is a possible ORF of 1272 nucleotides. The ORF designated sanV was deposited in GenBank under accession no. AF469955. Database search indicated that the deduced protein of sanV shows 28% identity and 44% similarity over 405 amino acid residues to the large component (E) of glutamate mutases from Clostridium cochlearium. Gene disruption was performed to study the function of sanV. It was found that sanV disruptants exhibited much poorer inhibition to the test strain than the wild-type S. ansochromogenes 7100. Furthermore, HPLC analysis indicated that the sanV disruptants almost did not produce nikkomycins X and Z, whereas they accumulated new nikkomycins O(x) and O(z), which revealed that sanV is an important gene involved in the biosynthesis of the peptidyl moiety of nikkomycins.

Amino Acid Sequence↗

PubMed2003

A standard for silver CP/MAS experiments.

Silver methanesulfonate, AgSO3CH3, is a photo-stable, commercially available compound which is a superior 109Ag standard for setting up CP/MAS experiments. The 109Ag CP/MAS spectrum at moderate sample spinning speeds easily yields a single, relatively narrow peak with a single transient. The 109Ag chemical shift of solid AgSO3CH3 is 87.2 ppm with respect to a 9 M aqueous solution of AgNO3. The static spectrum yields chemical shift tensor components delta11=191 ppm, delta22=63 ppm and delta33=8 ppm. Therefore the span, Omega, is 183 ppm and the skew, kappa, is -0.39. These values are in accord with the known crystal structure.

Calibration↗

PubMed2003

Disruption of sabR affects nikkomycin biosynthesis and morphogenesis in Streptomyces ansochromogenes.

The gene, sabR, encoding a receptor for gamma-butyrolactone, was cloned from the genomic DNA of Streptomyces ansochromogenes 7100. Its deduced protein shows strong homology to several gamma-butyrolactone-binding proteins in Streptomyces. Disruption of sabR retarded nikkomycin production in liquid media containing glucose or glycerol as carbon source. Sporulation of sabR disruption mutants was earlier than the parent strain on solid media with glucose or glycerol as carbon source. However, disruption of sabR had no effect on either nikkomycin production or sporulation on media containing mannitol as carbon source, suggesting that sabR is a pleiotropic regulatory gene that controls the onset of nikkomycin production and sporulation in S. ansochromogenes and is related to the utilization of carbon source.

4-Butyrolactone↗

PubMed2003

Construction of targeting vector and expression of green fluorescent protein in the silkworm, Antheraea pernyi.

The transcription initiation site of Anrheraea pernyi was identified, and a gene targeting vector was constructed. The green fluorescent protein (GFP) gene was inserted into this vector under the control of a fibroin promoter. This recombinant vector was used to target the GFP gene to the fibroin region of the silkworm genome. The DNA was injected into the testes during the pupae, and was also transferred into the egg via the sperm during fertilization. The analysis showed that the GFP gene was integrated into the fibroin gene on the genome by homologous recombination, and was expressed in the silk gland.

Animals↗