| 9862142 |
Destruxin Ed1 a cyclopeptide from the fungus Metarhizium anisopliae |
10.1016/s0031-9422(98)00337-9. |
Phytochemistry |
Destruxin Ed1 a cyclopeptide from the fungus Metarhizium anisopliae
Abstract
- A new destruxin Ed1 has been isolated from the entomopathogenic fungus Metarhizium anisopliae. Its structure was deduced from the NMR and mass spectral data.
|
| 9864322 |
Molecular and biochemical characterization of the protein template controlling biosynthesis of the lipopeptide lichenysin |
10.1128/JB.181.1.133-140.1999. |
J Bacteriol |
Molecular and biochemical characterization of the protein template controlling biosynthesis of the lipopeptide lichenysin
Abstract
- Lichenysins are surface-active lipopeptides with antibiotic properties produced nonribosomally by several strains of Bacillus licheniformis. Here, we report the cloning and sequencing of an entire 26.6-kb lichenysin biosynthesis operon from B. licheniformis ATCC 10716. Three large open reading frames coding for peptide synthetases, designated licA, licB (three modules each), and licC (one module), could be detected, followed by a gene, licTE, coding for a thioesterase-like protein. The domain structure of the seven identified modules, which resembles that of the surfactin synthetases SrfA-A to -C, showed two epimerization domains attached to the third and sixth modules. The substrate specificity of the first, fifth, and seventh recombinant adenylation domains of LicA to -C (cloned and expressed in Escherichia coli) was determined to be Gln, Asp, and Ile (with minor Val and Leu substitutions), respectively. Therefore, we suppose that the identified biosynthesis operon is responsible for the production of a lichenysin variant with the primary amino acid sequence L-Gln-L-Leu-D-Leu-L-Val-L-Asp-D-Leu-L-Ile, with minor Leu and Val substitutions at the seventh position.
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| 9865955 |
Localization of basic residues required for receptor binding to the single alpha-helix of the receptor binding domain of human alpha2-macroglobulin |
10.1002/pro.5560071214. |
Protein Sci |
Localization of basic residues required for receptor binding to the single alpha-helix of the receptor binding domain of human alpha2-macroglobulin
Abstract
- To better understand the structural basis for the binding of proteinase-transformed human alpha2-macroglobulin (alpha2M) to its receptor, we have used three-dimensional multinuclear NMR spectroscopy to determine the secondary structure of the receptor binding domain (RBD) of human alpha2M. Assignment of the backbone NMR resonances of RBD was made using 13C/15-N and 15N-enriched RBD expressed in Escherichia coli. The secondary structure of RBD was determined using 1H and 13C chemical shift indices and inter- and intrachain nuclear Overhauser enhancements. The secondary structure consists of eight strands in beta-conformation and one alpha-helix, which together comprise 44% of the protein. The beta-strands form three regions of antiparallel beta-sheet. The two lysines previously identified as being critical for receptor binding are located in (Lys1374), and immediately adjacent to (Lys1370) the alpha-helix, which also contains an (Arg1378). Secondary structure predictions of other alpha-macroglobulins show the conservation of this alpha-helix and suggest an important role for this helix and for basic residues within it for receptor binding.
|
| 9873474 |
Actinomycin D, C2 and VII, inhibitors of Grb2-SHC interaction produced by Streptomyces |
10.1016/s0960-894x(98)00345-x. |
Bioorg Med Chem Lett |
Actinomycin D, C2 and VII, inhibitors of Grb2-SHC interaction produced by Streptomyces
Abstract
- Actinomycin D, C2 and VII, cyclic peptides, inhibited Grb2 SH2 domain association (IC50 5-7 microM) with a phosphotyrosine containing peptide derived from the Shc protein (pTyr317). Actinomycins are the first examples of nonphosphorylated natural ligands of SH2 domain.
|
| 9878410 |
Solution structure by NMR of circulin A: a macrocyclic knotted peptide having anti-HIV activity |
10.1006/jmbi.1998.2276. |
J Mol Biol |
Solution structure by NMR of circulin A: a macrocyclic knotted peptide having anti-HIV activity
Abstract
- The three-dimensional solution structure of circulin A, a 30 residue polypeptide from the African plant Chassalia parvifolia, has been determined using two-dimensional 1H-NMR spectroscopy. Circulin A was originally identified based upon its inhibition of the cytopathic effects and replication of the human immunodeficiency virus. Structural restraints consisting of 369 interproton distances inferred from nuclear Overhauser effects, and 21 backbone dihedral and nine chi1 angle restraints from spin-spin coupling constants were used as input for simulated annealing calculations and energy minimisation in the program X-PLOR. The final set of 12 structures had mean pairwise rms differences over the whole molecule of 0.91 A for the backbone atom, and 1.68 A for all heavy atoms. For the well-defined region encompassing residues 2-12 and 18-27, the corresponding values were 0.71 and 1.66 A, respectively. Circulin A adopts a compact structure consisting of beta-turns and a distorted segment of triple-stranded beta-sheet. Fluorescence spectroscopy provided additional evidence for a solvent-exposed Trp residue. The molecule is stabilised by three disulfide bonds, two of which form an embedded loop completed by the backbone fragments connecting the cysteine residues. A third disulfide bond threads through the centre of this loop to form a "cystine-knot" motif. This motif is present in a range of other biologically active proteins, including omega-contoxin GVIA and Cucurbita maxima trypsin inhibitor. Circulin A belongs to a novel class of macrocyclic peptides which have been isolated from plants in the Rubiaceae family. The global fold of circulin A is similar to kalata B1, the only member of this class for which a structure has previously been determined.
|
| 9885189 |
Snakin-1, a peptide from potato that is active against plant pathogens |
10.1094/MPMI.1999.12.1.16. |
Mol Plant Microbe Interact |
Snakin-1, a peptide from potato that is active against plant pathogens
Abstract
- A new type of antimicrobial peptide, snakin-1 (SN1), has been isolated from potato tubers and found to be active, at concentrations < 10 microM, against bacterial and fungal pathogens from potato and other plant species. The action of SN1 and potato defensin PTH1 was synergistic against the bacterium Clavibacter michiganensis subsp. sepedonicus and additive against the fungus Botrytis cinerea. Snakin-1 causes aggregation of both gram-positive and gram-negative bacteria. The peptide has 63 amino acid residues (M(r) 6,922), 12 of which are cysteines, and is unrelated to any previously isolated protein, although it is homologous to amino acid sequences deduced from cloned cDNAs that encode gibberellin-inducible mRNAs and has some sequence motifs in common with kistrin and other hemotoxic snake venoms. A degenerate oligonucleotide probe based on the internal sequence CCEECKC has been used to clone an SN1 cDNA. With the cDNA used as probe, one copy of the StSN1 gene per haploid genome has been estimated and expression of the gene has been detected in tubers, stems, axillary buds, and young floral buds. Expression levels in petals and carpels from fully developed flowers were much higher than in sepals and stamens. The expression pattern of gene StSN1 suggests that protein SN1 may be a component of constitutive defense barriers, especially those of storage and reproductive plant organs.
|
| 9917006 |
A new anti-MRSA antibiotic complex, WAP-8294A. I. Taxonomy, isolation and biological activities |
10.7164/antibiotics.51.929. |
J Antibiot (Tokyo) |
A new anti-MRSA antibiotic complex, WAP-8294A. I. Taxonomy, isolation and biological activities
Abstract
- WAP-8294A, produced by Lysobacter sp., is a complex consisting of water soluble depsipeptide antibiotics. It was further purified by column chromatographies and HPLC, and 19 components were obtained. WAP-8294A2, a major component, and minor components A1, A4, Ax8, Ax9 and Ax13 were active against gram-positive bacteria, in particular, methicillin-resistant Staphylococcus aureus (MRSA) in vitro. WAP-8294A2 was highly active in vivo in mice against the systemic infection of MRSA.
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| 9918560 |
Hepatobiliary transport governs overall elimination of peptidic endothelin antagonists in rats |
None |
J Pharmacol Exp Ther |
Hepatobiliary transport governs overall elimination of peptidic endothelin antagonists in rats
Abstract
- The overall disposition and hepatobiliary transport of BQ-123, an anionic cyclopentapeptide, and three analogs were examined in rats in vivo. Total body clearance (CLtotal) and biliary excretion clearance (CLbile, p) exhibited 4- to 8-fold differences between the compounds, with those for BQ-485 and compound A having the highest and lowest values, respectively. The CLbile, p values of BQ-485, BQ-123, and BQ-518 were almost equal to the CLtotal, suggesting that hepatobiliary transport is the major elimination pathway for these compounds. Hepatic uptake clearance (CLuptake, vivo) and biliary excretion clearance (CLbile, h/fT), which was defined for the hepatic unbound concentration, were separately determined to examine the hepatic uptake and excretion processes, respectively. Both the CLuptake, vivo and CLbile, h/fT of BQ-485 were higher than those of BQ-123, whereas the corresponding values for BQ-518 were similar to those for BQ-123. The CLuptake, vivo and CLbile, h/fT of compound A were, respectively, approximately two thirds and one half those of BQ-123, suggesting that the lower CLbile, p value is due to the low efficiency of both the uptake and excretion processes. The CLuptake, vivo of these four peptides in vivo was similar to the extrapolated values based on the carrier-mediated transport activity previously assessed in vitro in isolated rat hepatocytes. The primary active transport previously assessed in an in vitro study in canalicular membrane vesicles was also highest for BQ-485 and lowest for compound A, similar to CLbile, h/fT in vivo. Thus, the transporters on both the sinusoidal and canalicular membranes determine the efficiency of the peptide overall elimination from the circulation.
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| 9918561 |
Primary active transport of peptidic endothelin antagonists by rat hepatic canalicular membrane |
None |
J Pharmacol Exp Ther |
Primary active transport of peptidic endothelin antagonists by rat hepatic canalicular membrane
Abstract
- The biliary excretion mechanism of three derivatives of BQ-123, an anionic cyclopentapeptide, was examined using isolated canalicular membrane vesicles (CMVs) from Sprague-Dawley rats. The uptake by CMV of BQ-485, a linear peptide, BQ-518, a cyclic peptide, and compound A, a cyclic peptide with a cationic moiety, was stimulated by ATP. An "overshoot" phenomenon and saturation were observed for the ATP-dependent uptake of these three peptides. The Michaelis-Menten constants (Km) for the uptake of BQ-485 and BQ-518 were comparable to the inhibition constants (Ki) for their inhibitory effects on ATP-dependent 3HBQ-123 uptake. The uptake of BQ-485 showed the highest value and was inhibited by BQ-123 with a Ki that was comparable to the Km for BQ-123 uptake. The ATP-dependent uptake of BQ-123, BQ-485, and BQ-518 was much lower in CMVs from Eisai hyperbilirubinemic rats, a strain having a hereditary defect of the canalicular multispecific organic anion transporter (cMOAT). These results suggest that both BQ-485 and BQ-518 principally share the cMOAT transporter with BQ-123. Compound A almost completely inhibited BQ-123 uptake, although its ATP-dependent uptake was much lower than that of the other three peptides. The ATP-dependent uptake of compound A was not very different in Sprague-Dawley rats and Eisai hyperbilirubinemic rats and was not inhibited by S-(2, 4-dinitrophenyl)-glutathione, a typical substrate for cMOAT. Thus, although compound A inhibits cMOAT-mediated transport, its own transport by cMOAT is minimal and mediated by another transporter. This low degree of primary active transport by cMOAT may be the principal reason for its relatively longer residence in the circulation.
|
| 9918823 |
A low-molecular-weight inhibitor against the chemokine receptor CXCR4: a strong anti-HIV peptide T140 |
10.1006/bbrc.1998.9871. |
Biochem Biophys Res Commun |
A low-molecular-weight inhibitor against the chemokine receptor CXCR4: a strong anti-HIV peptide T140
Abstract
- T22 (Tyr5,12, Lys7-polyphemusin II) is an 18-residue peptide amide, which has strong anti-HIV activity. T22 inhibits the T cell line-tropic (T-tropic) HIV-1 infection through its specific binding to a chemokine receptor CXCR4, which serves as a coreceptor for the entry of T-tropic HIV-1 strains. Herein, we report our finding of novel 14-residue CXCR4 inhibitors, T134 and T140, on the basis of the T22 structure. In the assays we examined, T140 showed the highest inhibitory activity against HIV-1 entry and the strongest inhibitory effect on the binding of an anti-CXCR4 monoclonal antibody (12G5) to CXCR4 among all the CXCR4 inhibitors that have been reported up to now.
|
| 9925088 |
The utility of a somatostatin-type receptor binding peptide radiopharmaceutical (P829) in the evaluation of solitary pulmonary nodules |
10.1378/chest.115.1.224. |
Chest |
The utility of a somatostatin-type receptor binding peptide radiopharmaceutical (P829) in the evaluation of solitary pulmonary nodules
Abstract
- Many neoplasms including small cell cancers more densely express somatostatin-type receptors or more avidly bind somatostatin than granulomatous and other nonmalignant processes. While non-small cell neoplasms of the lung have not yet been shown to demonstrate this receptor expression, previous studies have documented non-small cell lung cancer detection with somatostatin analog scintigraphy. This phenomenon can be conceivably exploited utilizing technetium Tc-99m P829 (P829), a unique low molecular weight somatostatin-type receptor binding polypeptide radiopharmaceutical. The objective of this study was to determine the ability of P829 scintigraphy to noninvasively differentiate malignant and nonmalignant solitary pulmonary nodules (SPNs).\n \n \n \n \n The radiopharmaceutical technetium 99mTc-P829 was utilized for scintigraphy including single photon emission computed tomography. Thirty individuals with indeterminate SPNs of > or = 1 cm and significant risk factors for primary lung cancer were identified and underwent P829 scintigraphy. Tissue diagnosis was then established by transthoracic needle biopsy specimens.\n \n \n \n \n Fourteen subjects demonstrated abnormal P829 scans in the region of the radiographic abnormality. Twelve of this group had biopsy specimens revealing neoplasia. Two subjects with necrotizing granuloma on biopsy specimen had abnormal P829 scans in the region of the nodule. Sixteen subjects had no abnormal P829 tracer uptake in the region of the nodule. Fourteen subjects had benign diagnoses on biopsy specimens. One member of this group with a non-diagnostic biopsy specimen refused thoracotomy and remains radiographically stable at 24 months of follow-up. One subject with a squamous cell carcinoma demonstrated no P829 activity in the region of the nodule. The specificity of P829 scintigraphy based on transthoracic needle biopsy specimen was 88%. The sensitivity was 93%. P829 scintigraphy correctly identified or excluded malignancy in 27 of 30 subjects.\n \n \n \n \n P829 scintigraphy reliably identified or excluded malignancy in radiographically indeterminate solitary pulmonary nodules. The sensitivity and specificity compared favorably with the reported results of F-18 fluorodeoxyglucose positron emission tomographic imaging.
|
| 10022120 |
Tyrosine phosphorylation and complex formation of Cbl-b upon T cell receptor stimulation |
10.1038/sj.onc.1202411. |
Oncogene |
Tyrosine phosphorylation and complex formation of Cbl-b upon T cell receptor stimulation
Abstract
- Cbl-b, a mammalian homolog of Cbl, consists of an N-terminal region (Cbl-b-N) highly homologous to oncogenic v-Cbl, a Ring finger, and a C-terminal region containing multiple proline-rich stretches and potential tyrosine phosphorylation sites. In the present study, we demonstrate that upon engagement of the T cell receptor (TCR), endogenous Cbl-b becomes rapidly tyrosine-phosphorylated. In heterogeneous COS-1 cells, Cbl-b was phosphorylated on tyrosine residues by both Syk- (Syk/Zap-70) and Src- (Fyn/Lck) family kinases, with Syk kinase inducing the most prominent effect. Syk associates and phosphorylates Cbl-b in Jurkat T cells. A Tyr-316 Cbl-binding site in Syk was required for the association with and for the maximal tyrosine phosphorylation of Cbl-b. Mutation at a loss-of-function site (Gly-298) in Cbl-b-N disrupts its interaction with Syk. Cbl-b constitutively binds Grb2 and becomes associated with Crk-L upon TCR stimulation. The Grb2- and the Crk-L-binding regions were mapped to the C-terminus of Cbl-b. The Crk-L-binding sites were further determined to be Y655DVP and Y709KIP, with the latter being the primary binding site. Taken together, these results implicate that Cbl-b is involved in TCR-mediated intracellular signaling pathways.
|
| 10026169 |
Identification of Grb4/Nckbeta, a src homology 2 and 3 domain-containing adapter protein having similar binding and biological properties to Nck |
10.1074/jbc.274.9.5542. |
J Biol Chem |
Identification of Grb4/Nckbeta, a src homology 2 and 3 domain-containing adapter protein having similar binding and biological properties to Nck
Abstract
- Adapter proteins made up of Src homology (SH) domains mediate multiple cellular signaling events initiated by receptor protein tyrosine kinases. Here we report that Grb4 is an adapter protein closely related to but distinct from Nck that is made up of three SH3 domains and one SH2 domain. Northern analysis indicated that both genes are expressed in multiple tissues. Both Nck and Grb4 proteins could associate with receptor tyrosine kinases and the SH3-binding proteins PAK, Sos1, and PRK2, and they synergized with v-Abl and Sos to induce gene expression via the transcription factor Elk-1. Although neither protein was transforming on its own, both Nck and Grb4 cooperated with v-Abl to transform NIH 3T3 cells and influenced the morphology and anchorage-dependent growth of wild type Ras-transformed cells. Nck and Grb4 therefore appear to be functionally redundant.
|
| 10048485 |
Prediction of the coding sequences of unidentified human genes. XII. The complete sequences of 100 new cDNA clones from brain which code for large proteins in vitro. |
10.1093/dnares/5.6.355 |
DNA Res. |
Prediction of the coding sequences of unidentified human genes. XII. The complete sequences of 100 new cDNA clones from brain which code for large proteins in vitro.
Abstract
- In this paper, we report the sequences of 100 cDNA clones newly determined from a set of size-fractionated human brain cDNA libraries and predict the coding sequences of the corresponding genes, named KIAA0819 to KIAA0918. These cDNA clones were selected on the basis of their coding potentials of large proteins (50 kDa and more) by using in vitro transcription/translation assays. The sequence data showed that the average sizes of the inserts and corresponding open reading frames are 4.4 kb and 2.5 kb (831 amino acid residues), respectively. Homology and motif/domain searches against the public databases indicated that the predicted coding sequences of 83 genes were similar to those of known genes, 59% of which (49 genes) were categorized as coding for proteins functionally related to cell signaling/communication, cell structure/motility and nucleic acid management. The chromosomal locations and the expression profiles of all the genes were also examined. For 54 clones including brain-specific ones, the mRNA levels were further examined among 8 brain regions (amygdala, corpus callosum, cerebellum, caudate nucleus, hippocampus, substantia nigra, subthalamic nucleus, and thalamus), spinal cord, and fetal brain.
|
| 10051406 |
The gene structure of the human growth factor bound protein GRB2 |
10.1006/geno.1998.5692. |
Genomics |
The gene structure of the human growth factor bound protein GRB2
Abstract
- The growth factor bound protein GRB2, a 25-kDa cytosolic protein, plays a key role in two separate pathways of the insulin signal transduction system leading from the insulin receptor to the Ras proteins and thus affecting mitogenic signaling. GRB2 regulates Ras activation through association with the guanine nucleotide exchange factor Sos. The GRB2/Sos complex can connect with insulin receptor substrate 1 (IRS-1), which is one of the primary targets of the insulin and insulin-like growth factor receptors. In a second pathway, independent of IRS-1, GRB2 links the insulin receptor to Ras signaling through another adapter protein, called Shc. In protooncogenic and other noninsulin signaling systems, GRB2 appears to link receptor tyrosine kinases to Ras in similar pathways as well. This study presents the exon-intron organization of the human GRB2 gene. After primers were placed across the known mRNA sequence, Long PCR products spanning introns and their adjacent splice sites were amplified and adequately sequenced to establish the splice sites and flanking regions. The gene was found to consist of five exons (ranging from 78 to 186 bp) and of four introns (from approximately 1 to approximately 7 kb). Intron primers for the respective exons were generated using the newly found flanking sequences. All exons were successfully amplified and sequenced, and the data obtained from Long PCR sequencing were confirmed.
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