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1.
A mutation at proline-115 in the A-factor receptor protein of Streptomyces griseus abolishes DNA-binding ability but not ligand-binding ability. 总被引:2,自引:0,他引:2 下载免费PDF全文
A-factor (2-isocapryloyl-3R-hydroxymethyl-gamma-butyrolactone) and its specific receptor protein (ArpA) are required for streptomycin production and aerial mycelium formation in Streptomyces griseus. A mutant strain HO1 that produced streptomycin and formed aerial mycelium and spores was derived from an A-factor-deficient mutant, S. griseus HH1. The phenotypes of mutant HO1 were found to result from a single amino acid replacement of ArpA; the proline residue at position 115 in the wild-type ArpA was replaced by serine, yielding mutant ArpA (P115S). The mutant ArpA (P115S) was still able to form a homodimer and possessed A-factor-binding ability but lost the ability to bind DNA. The properties of P115S suggest that ArpA consists of two independently functional domains, one for A-factor binding and one for DNA binding, and that proline-115 plays an important role in DNA binding. This is in agreement with the idea that A-factor binding to the COOH-terminal domain of ArpA causes a subtle conformational change of the distal NH2-terminal DNA-binding domain, resulting in dissociation of ArpA from DNA. 相似文献
2.
DON AT AGOSTI 《Systematic Entomology》1994,19(2):93-117
Abstract. The holarctic ant tribe Formicini is revised, the new genus Bajcaridris described, and possible phylogenetic relationships are discussed. The subgenus Iberoformica is synonymized with Formica. A synopsis, diagnosis and keys to the genera are provided. 相似文献
3.
Hoshino Shotaro Onaka Hiroyasu Abe Ikuro 《Journal of industrial microbiology & biotechnology》2019,46(3-4):363-374
Journal of Industrial Microbiology & Biotechnology - Bacterial secondary metabolites (SM) are rich sources of drug leads, and in particular, numerous metabolites have been isolated from... 相似文献
4.
Desulfurization of Benzothiophene by the Gram-Negative Bacterium, Sinorhizobium sp. KT55 总被引:3,自引:0,他引:3
Sinorhizobium sp. KT55 was the first Gram-negative isolate to be capable of utilizing benzothiophene as the sole source of sulfur. By GC-MS
analysis of metabolites of benzothiophene by this strain, benzothiophene sulfone, benzo[e][1,2]oxathiin S-oxide and o-hydroxystyrene were detected, suggesting that the benzothiophene desulfurization pathway of this strain is benzothiophene
→ benzothiophene sulfoxide → benzothiophene sulfone → benzo[e][1,2]oxathiin S-oxide →o-hydroxystyrene. Desulfurization activity of this strain was significantly repressed by methionine, cysteine, sulfate, dimethyl
sulfoxide, and Casamino acids.
Received: 5 January 2001/Accepted: 6 February 2001 相似文献
5.
本文报道海拔3417m和4280m地区世居藏族和移居汉族青少年运动状态下心肺功能的对比研究。结果显示:3417m和4280m世居藏族的最大氧耗量、无氧阈值及最大心输出量都明显大于汉族,血氧饱和度(Sao2)随运动负荷的增加而降低。海拔3417m藏、汉族的△Sao2分别为7.46%和10.03%,4280m处为8.57%和13.75%,最大心率随海拔升高而下降。研究提示,藏族青少年有较高的最大有氧能力,反映了他们对低氧环境的适应优势。 相似文献
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A benzothiophene (BT) and dibenzothiophene (DBT) monooxygenase (TdsC), which catalyzes the oxidation of the sulfur atoms in BT and DBT molecules, was purified from Paenibacillus sp. strain A11-2. The molecular mass of the purified enzyme and its subunit were determined to be 200 kDa and 43 kDa by gel filtration and sodium dodecyl sulfate polyacrylamide gel electrophoresis, respectively, indicating a tetrameric structure. The N-terminal amino acid sequence of the purified TdsC completely matched the amino acid sequence deduced from the nucleotide sequence of the tdsC gene reported previously [Ishii et al. (2000) Biophys Biochem Res Commun 270:81-88]. The optimal temperature and pH for the TdsC reaction were 65 degrees C and pH 9, respectively. TdsC required NADH, FMN and TdsD, a NADH-dependent FMN oxidoreductase, for its activity, as was observed for TdsA. FAD, lumiflavin and/or NADPH had some effect on the maintenance of TdsC activity. A comparison of the substrate specificity of TdsC and DszC, the homologous monooxygenase purified from Rhodococcus erythropolis strain KA2-5-1, demonstrated a contrasting pattern towards alkylated DBTs and BTs. 相似文献
9.
The effects of adrenomedullin (AM) and proadrenomedullin N-terminal 20 peptide (PAMP) on membrane potential and sympathetic neurotransmission were studied in rat mesenteric arteries by using microelectrodes. AM (10(-7) M) but not PAMP (10(-6) M) produced membrane hyperpolarization, which was abolished by high K solution or by glibenclamide, an ATP-sensitive K(+) (KATP) channel blocker. Neither AM nor PAMP affected excitatory junction potentials, a measure of sympathetic, purinergic neurotransmission. These findings suggest that AM hyperpolarizes the membrane via activation of KATP channels, which may contribute to the vasodilatory action of AM, whereas the mechanisms of the vasodepressor action of PAMP remain unclear. 相似文献
10.
Subsequent to the isolation of the first recognized RFamide neuropeptide, FMRFamide, from the clam, a large number of these peptides have been identified. There are now five groups of RFamide peptides identified in mammals. RFamide peptides show diversity with respect to their N-terminal sequence and biological activity. RFamide peptides have been implicated in a variety of roles, including energy metabolism, stress and pain modulation, as well as effects in the neuroendocrine and cardiovascular systems. In the present minireview, we focus on prolactin-releasing peptide (PrRP) and RFamide related peptide (RFRP) with respect to their roles in the control of energy metabolism and stress responses. Both food intake and stressful stimuli activate PrRP neurons. The administration of PrRP affects energy metabolism and neuroendocrine systems. PrRP-deficient or PrRP receptor-deficient mice show abnormal energy metabolism and/or stress responses. On the other hand, RFRP neurons are activated by stressful stimuli and the administration of RFRP induces neuroendocrine and behavioral stress responses. Taken together, these data suggests that PrRP and RFRP neurons play a role in the control of energy metabolism and/or stress responses. 相似文献