The nusG gene of Streptomyces griseus: Cloning of the gene and analysis of the A-factor binding properties of the gene product

Abstract The nusG gene of Streptomyces griseus was cloned and the nucleotide sequence determined. It encodes a protein with an identify of 76% to the reported receptor (VbrA) for VB-C, an autoregulatory factor in Streptomyces virginae . NusG protein was expressed in Escherichia coli . However, no binding activity for A-factor, an butyrolactone autoregulator in S. griseus very similar to VB-C, could be detected. The nusG gene of S. griseus does not seem to encode the A-factor-binding protein.     

Purification and Characterization of Membrane Protein (90 kDa) from Mycoplasma salivarium,Which Binds Immunoglobulin (Ig) G Fc Fragment

A 90 kDa protein of Mycoplasma salivarium was released from cell membranes of the organism with Triton X-100 and purified by ion-exchange chromatography and chromatofocusing. The protein was eluted at pH 5.5 by chromatofocusing. The protein was shown to react with the Fc fragments of IgG from human and nine different animal species and did not distinguish between IgG from different species, while protein A, tested for comparative purposes, displayed a strong specificity for human and swine IgG. Furthermore, the protein reacted with antigen specific goat IgG (specific for gamma chains of human IgG), sheep red blood cells (SRBC) sensitized with rabbit antiserum to SRBC, that is, the Fc part of rabbit IgG, and concanavalin A as well. These findings may suggest that the protein is a lectin which binds the carbohydrate moiety of the Fc part of IgG.     

Herpes Simplex Virus-Induced Expression of 70 kDa Heat Shock Protein (HSP70) Requires Early Protein Synthesis But Not Viral DNA Replication

The major 70 kDa heat shock protein (HSP70), which is scarcely expressed in unstressed rodent cells, was apparently induced by infection with herpes simplex virus (HSV). Infection with HSV types 1 and 2 elevated HSP70 mRNA levels within 4 hr post-infection. HSP70 synthesis and accumulation increased in HSV-infected cells. Irradiation of HSV with UV-light abolished the ability to induce HSP70 mRNA. Inhibitors of viral DNA synthesis did not affect the induction of HSP70 in infected cells. Protein synthesis within 2 hr after infection was necessary for HSP70 induction.     

野生大豆种子蛋白含量差异的生理及结构基础的探讨

利用ＳＤＳ－聚丙烯酰胺凝胶电泳、电子显微镜、蛋白及酰脲含量测定等技术,对高蛋白含量（５０．７％ ）的５０３５９ 和低蛋白含量（４０．８％ ）的５０３０５ 两个野生大豆在种子发育过程中贮藏蛋白积累的速率、蛋白组分合成的起始时间、蛋白体发育的进程以及幼茎的酰脲含量进行了比较研究。结果表明：野生大豆５０３５９的高蛋白含量是与其种子发育过程中较高的植株酰脲含量、较早较快的贮藏蛋白合成及积累速率,液泡中高效的蛋白贮藏方式以及蛋白体在子叶细胞中占有较大体积相联系的     

双价外壳蛋白基因植物表达载体的构建及马铃薯转基因植株的鉴定

在克隆了马铃薯Ｘ病毒（ＰＶＸ）、马铃薯Ｙ 病毒（ＰＶＹ）和马铃薯卷叶病毒（ＰＬＲＶ）的外壳蛋白基因的基础上,构建同时包含ＰＶＸ和ＰＶＹ 与ＰＶＹ 和ＰＬＲＶ 两个外壳蛋白基因植物表达框架的表达载体,通过农杆菌（Ａｇｒｏｂａｃｔｅｒｉｕｍ ｔｕｍｅｆａｃｉｅｎｓ）介导转化烟草（Ｎｉｃｏｔｉａｎａｔａｂａｃｕｍ ）和生产上常用的几个马铃薯（Ｓｏｌａｎｕｍ ｔｕｂｅｒｏｓｕｍ ）优良品种：“Ｆａｖｏｒｉｔａ”、“虎头”、“克４”。经ＰＣＲ检测证明外源基因已整合到植物的染色体上,得到批量转基因植株。在转ＰＶＸ＋ＰＶＹ 外壳蛋白基因的烟草上接种ＰＶＸ （５ μｇ／ｍ Ｌ）、ＰＶＹ（２０ μｇ／ｍ Ｌ）病毒,得到有一定抗性的植株     

花粉高尔基囊泡与牛脑微管的体外结合

把从榛木（Ｃｏｒｙｌｕｓａｖｅｌｌａｎａ Ｌ．）花粉中分离得到的高尔基囊泡与经高度纯化并聚合好的牛脑微管进行体外组合,然后于１．５ ｍ ｏｌ／Ｌ的蔗糖层上进行超离心,对其沉淀物进行ＳＤＳ－聚丙烯酰胺凝胶电泳和电镜负染。结果表明,花粉高尔基囊泡可以结合到牛脑微管上,证明植物花粉的高尔基囊泡与动物细胞的某些细胞器一样,也与细胞骨架的主要组成之一——微管具有结构上的紧密联系。花粉高尔基囊泡与牛脑微管的体外结合能力,受１０ ｍ ｍ ｏｌ／ＬＡＴＰ和０．５ ｍ ｏｌ／ＬＫＣｌ的影响,但不受５ ｍ ｍ ｏｌ／Ｌ ＡＭＰ－ＰＮＰ的影响,说明两者结合可能是通过高尔基囊泡表面与ＡＴＰ有关的某种外周膜蛋白来完成的。     

A method for α-helical integral membrane protein fold prediction

Integral membrane proteins (of the α-helical class) are of central importance in a wide variety of vital cellular functions. Despite considerable effort on methods to predict the location of the helices, little attention has been directed toward developing an automatic method to pack the helices together. In principle, the prediction of membrane proteins should be easier than the prediction of globular proteins: there is only one type of secondary structure and all helices pack with a common alignment across the membrane. This allows all possible structures to be represented on a simple lattice and exhaustively enumerated. Prediction success lies not in generating many possible folds but in recognizing which corresponds to the native. Our evaluation of each fold is based on how well the exposed surface predicted from a multiple sequence alignment fits its allocated position. Just as exposure to solvent in globular proteins can be predicted from sequence variation, so exposure to lipid can be recognized by variable-hydrophobic (variphobic) positions. Application to both bacteriorhodopsin and the eukaryotic rhodopsin/opsin families revealed that the angular size of the lipid-exposed faces must be predicted accurately to allow selection of the correct fold. With the inherent uncertainties in helix prediction and parameter choice, this accuracy could not be guaranteed but the correct fold was typically found in the top six candidates. Our method provides the first completely automatic method that can proceed from a scan of the protein sequence databanks to a predicted three-dimensional structure with no intervention required from the investigator. Within the limited domain of the seven helix bundle proteins, a good chance can be given of selecting the correct structure. However, the limited number of sequences available with a corresponding known structure makes further characterization of the method difficult. © 1994 John Wiley & Sons, Inc.