链霉菌大肠杆菌穿梭质粒载体pSGLgpp的构建及应用

质粒pSGL1(74kb)是从球孢链霉菌(\%Streptomyces geobisporus)\%中分离得到的一个高拷贝质粒,已测定其最小复制子序列。从球孢链霉菌总DNA中采用PCR方法扩增获得编码C1027前蛋白信号肽的DNA片断gpp。将gpp克隆至pSGL1的衍生质粒pSGLN中,获得新的链霉菌表达型质粒载体pSGLgpp。应用该质粒进行了人的河溶性白细胞介素1受体I型的表达。     

链霉菌—大肠菌穿梭质袜载体pSGLgpp的构建及应用

质粒ｐＳＧＬ１（７．４ｋｂ）是从球孢链霉菌（Ｓｔｒｅｐｔｏｍｙｃｅｓ ｇｅｏｂｉｓｐｏｒｕｓ）中分离得到的一个高拷贝质粒,已测定其最小复制子序列。从球孢链霉菌总ＤＮＡ中采用ＰＣＲ方法扩增获得编码Ｃ１０２７前蛋白信号肽的ＤＮＡ片断ｇｐｐ。将ｇｐｐ克隆至ｐＳＧＬ１的衍生质粒ｐＳＧＬＮ中,获得新的链霉菌表达型质粒载体ｐＳＧＬｇｐｐ。应用该质粒进行了人的河溶性白细胞介素１受体Ｉ型的表达。     

力达霉素产生菌球孢链霉菌C-1027中atrA同源基因的克隆及分析

目的：在天蓝色链霉菌Streptomyces coelicolor A3(2)中多效性调节因子AtrA（AtrA-c）可通过激活放线紫红素途径特异性的调节因子ActII-ORF4的转录来控制放线紫红素的产生。在灰色链霉菌Streptomyces griseus NBRC13350和阿维链霉菌Streptomyces avermitilis MA-4680中也发现了AtrA-c 编码基因（atrA-c）的同源基因,分别影响链霉素和阿维菌素的生物合成。本文目的在于探索球孢链霉菌C-1027（Streptomyces globisporus C-1027）中是否存在AtrA,克隆球孢链霉菌C-1027中atrA基因并进行生物信息学分析,为进一步确定其对力达霉素产生的调控作用及调控机制奠定基础。[方法] 采用在球孢链霉菌C-1027中异源表达AtrA-c,来确定AtrA-c对力达霉素产量的影响;通过Southern blot 分析来判断在球孢链霉菌C-1027 基因组中是否有atrA-c同源基因;PCR扩增方法获得球孢链霉菌C-1027 atrA基因（atrA-gl）并测序;通过多种生物信息学软件来分析atrA-gl及其与旁侧基因的组织结构、对已发现的AtrA蛋白进行同源性比对及亲缘关系分析。[结果]在球孢链霉菌C-1027中异源表达天蓝色链霉菌AtrA-c蛋白,发现其对力达霉素的产量有影响。以atrA-c为探针,通过Southern blot分析显示球孢链霉菌C-1027基因组中存在atrA-c的同源基因。PCR扩增得到球孢链霉菌C-1027 的atrA基因的全序列以及该基因上下游的旁侧序列（GenBank/EMBL/DDBJ 登录号GU723707）。通过对球孢链霉菌C-1027、天蓝色链霉菌A3(2)、灰色链霉菌NBRC13350以及阿维链霉菌MA-4680 AtrA蛋白序列进行同源性分析发现,四种AtrA蛋白编码氨基酸序列一致性达到65%至 87%,相似性高达70% 至89%。并且,球孢链霉菌C-1027 atrA基因与相邻基因形成的组织结构与天蓝色链霉菌和灰色链霉菌完全一致。根据蛋白质同源性绘制进化树,发现球孢链霉菌AtrA蛋白与灰色链霉菌AtrA蛋白亲缘关系最近。[结论]确定在球孢链霉菌C-1027中存在atrA同源基因并影响力达霉素的产量,克隆了首个力达霉素生物合成基因簇外的调节基因--atrA基因,通过生物信息学分析初步推测了该基因的功能,为进一步研究AtrA-gl对力达霉素途径特异性级联调控网络的调控关系奠定了基础。     

球孢链霉菌质粒pSGL1的性质研究

链霉菌质粒pSGL1是本实验室在球孢链霉菌（Streptomycelglobisporus）中发现的新的质粒,它可以在变铅青链霉菌中复制。用缺失分析确定了pSGL1的基本复制区位于一个2．0kb的片段上。pSGL1能够与pIJ101相容。pSGL1是一个高拷贝质粒,拷贝数约为70～250。在对质粒进行分析的过程中得到的一些衍生质粒如pSGLN和pSGLS3等可以作为新的链霉菌基因克隆载体,并可用于构建新的高效分泌表达的链霉菌载体。     

双歧杆菌分泌RNA的实验

目的：通过双歧杆菌对数生长期培养液中出现核酸的性质的研究探索双歧杆菌作用于机体的分子机制。方法：采用液体培养双歧杆菌方法;提取对数生长的双歧杆菌培养发酵液中的总核酸;将纯化后的核酸用RNA降解酶降解,电泳观察核酸条带电泳结果。结果：双歧杆菌对数生长期培养发酵液中仅存在RNA。结论：双歧杆菌对数生长期可能分泌100bp RNA。     

糖多孢红霉菌多拷贝表达载体pZM的构建

对糖多孢红霉菌染色体上红霉素生物合成基因进行改造 ,已经合成了多种红霉素类似物。在糖多孢红霉菌中对红霉素类似物进行结构修饰 ,以pWOR1 0 9质粒为基础构建糖多孢红霉菌多拷贝表达载体pZM。pZM载体带有PermE启动子、fd终止子、多克隆位点、硫链丝菌肽和氨苄青霉素抗性基因、以及在大肠杆菌和糖多孢红霉菌中复制的ColE1ori和pJV1ori复制子 ,系可在大肠杆菌和糖多孢红霉菌中扩增的穿梭质粒。在糖多孢红霉菌中 ,pZM可以表达氨普霉素抗性基因和绿色荧光蛋白基因 ,从糖多孢红霉菌中提取的表达质粒酶切图谱与转化前一致 ,表明pZM是糖多孢红霉菌中多拷贝、稳定的表达载体。     

游动双孢菌线型质粒pPR2的全序列测定及分析

[目的]获得游动双孢菌线型质粒pPR2的全序列,并揭示新型的端粒复制蛋白和可能的中间复制位点.[方法]用分段克隆的方法和序列拼接获得pPR2的全序列,利用软件分析端粒DNA的二级结构和可能的端粒复制蛋白,利用链霉菌原生质体转化的方法检测可能的中间复制的位点.[结果]pPR2全长为15520 bp,(G C)含量为68.1%.其端粒末端反向重复序列的长度为329 bp,不能像多数链霉菌的线型质粒那样能形成保守的"折返"的二级结构.pPR2虽然没有参与链霉菌端粒复制的保守的tap/tpg基因,但是pPR2.3c基因编码了一个双结构域蛋白,分别同链霉菌的端粒复制相关蛋白Tap和嗜血杆菌的解旋酶具有相似性.pPR2缺少典型的链霉菌重复序列-复制基因(iteron-rep)区段,将几乎覆盖全长pPR2的两段DNA进行克隆后,不能转化变铅青链霉菌.此外,pPR2基因还编码可能参与线型DNA复制的调控的单链结合蛋白(SSB)和与放线菌质粒接合转移相关的主要蛋白(Tva).[结论]pPR2是链霉菌之外的放线菌中最小的线型质粒,其序列在游动双孢菌属的线型质粒中是首次报道.pPR2可能具有新型的端粒复制的机制,其中pPR2.2c和pPR2.3c编码可能的端粒复制蛋白.     

双歧杆菌质粒的检测及其对抗生素敏感性

本文应用ＬｅＢＬａｎｃ法提取６种２０株双歧杆菌菌株的质粒,发现共有４个种的６株菌株存在着１～３个质粒,多数质粒的分子量小于６．０ｋｂ。存在质粒的双歧杆菌包括分离自人的短双歧杆菌、青春双歧杆菌、两歧双岐杆菌和婴儿双歧杆菌。用固体培养基滤纸片抑菌圈法测定双歧杆菌对１５种常用抗生素的敏感性,结果表明,测试的２０株双歧杆菌菌株对所检测的１５种抗生素的敏感性无规律可循,而且质粒消除实验表明质粒的存在与所检测的抗生素抗性无相关性。     

一株拮抗可可球二孢菌放线菌的分离及鉴定

目的:筛选具有拮抗植物病原真菌可可球二孢菌活性的放线菌.方法:选择高氏一号培养基分离放线菌,以可可球二孢菌为指示菌进行抑菌活性筛选,通过形态学特征、生理生化特征、培养特征以及16S rRNA基因序列分析等研究对筛选得到的高活性菌株进行菌种鉴定.结果:从南方红豆杉根际土壤中筛选得到一株高活性菌株KLBMP 2284,16S rRNA基因序列比对结果显示其与弗吉尼亚链霉菌(Streptomyces virginiae)相似性98.963％,发酵液稀释300倍后抑制率为41.64％.结论:KLBMP 2284为弗吉尼亚链霉菌的一个菌株.     

双歧杆菌的耐药性与质粒

目的：研究双歧杆菌的耐药性与质粒的关系。方法 对１７株５种来自微生态制剂的双歧杆菌进行抗生素药敏试验和质粒检测,利用溴化乙锭消除其质粒;比较质粒消除前后耐药性的改变。结果１７株双歧杆菌对氨基糖式类和多肽类抗生素呈强抗性;除１株短型双歧杆菌Ｂ１５７存有２．７Ｋｂ和５．６Ｋｂ两种质粒外,其余菌株均未质粒,消除后持粒的Ｂ１５７株菌对抗生素的敏感性并未改变。结论 此１７株双歧杆菌的耐药性与质粒无直接相关性     

A rapid and efficient method of lysis of Listeria and other gram-positive bacteria using mutanolysin.

A rapid and simple procedure is described for cell lysis for preparation of nucleic acids and intact ribosomal RNA from Gram-positive bacteria. Commercial mutanolysin (purified from Streptomyces globisporus) was used for inducing lysis. Listeria, Lactobacillus and Lactococcus strains were very sensitive to mutanolysin when compared to lysozyme. Susceptibility to mutanolysin was improved by a preliminary treatment with acetone, and sodium dodecyl sulfate reduced the efficiency of lysis when used together with mutanolysin. The procedure was also effective for recovering plasmids from these bacteria.     

Glucosamine substitution and muramidase susceptibility in Bacillus anthracis

Cell walls of Bacillus anthracis were found to be resistant to lysozyme, and partially resistant to mutanolysin, a muramidase from Streptomyces globisporus. Following treatment with acetic anhydride, it was observed that the walls were highly susceptible to hydrolysis by lysozyme or mutanolysin. Analyses of cell walls, prior to and following derivatization with fluorodinitrobenzene, revealed that approximately 88% of the glucosamine residues and 34% of the muramic acid residues of the peptidoglycan contained unsubstituted amino groups, thereby providing an explanation for the resistance of the walls to lysozyme. The walls of B. anthracis were approximately 19% cross-linked, based on the findings that 81% of the diaminopimelic acid residues could be modified by fluorodinitrobenzene. Walls of B. thuringiensis 4040 and B. cereus ATCC 19637 also contained high percentages of unsubstituted amino sugars, and unless acetylated, were also relatively resistant to lysozyme and mutanolysin. When B. anthracis, B. cereus, or B. thuringiensis were grown in the presence of 100 micrograms/mL lysozyme, there was a decrease in the average number of cells per chain, but there was no decrease in growth rates, suggesting that the enzyme was acting at septa. It is unlikely that lysozyme and autolysins act synergistically in Bacillus, because azide anion, which activates autolysins, did not enhance the lytic action of lysozyme in B. anthracis, B. cereus, or B. thuringiensis.     

Cell wall substrate specificity of six different lysozymes and lysozyme inhibitory activity of bacterial extracts

We have investigated the specificity of six different lysozymes for peptidoglycan substrates obtained by extraction of a number of gram-negative bacteria and Micrococcus lysodeikticus with chloroform/Tris-HCl buffer (chloroform/buffer). The lysozymes included two that are commercially available (hen egg white lysozyme or HEWL, and mutanolysin from Streptomyces globisporus or M1L), and four that were chromatographically purified (bacteriophage lambda lysozyme or LaL, bacteriophage T4 lysozyme or T4L, goose egg white lysozyme or GEWL, and cauliflower lysozyme or CFL). HEWL was much more effective on M. lysodeikticus than on any of the gram-negative cell walls, while the opposite was found for LaL. Also the gram-negative cell walls showed remarkable differences in susceptibility to the different lysozymes, even for closely related species like Escherichia coli and Salmonella Typhimurium. These differences could not be due to the presence of lysozyme inhibitors such as Ivy from E. coli in the cell wall substrates because we showed that chloroform extraction effectively removed this inhibitor. Interestingly, we found strong inhibitory activity to HEWL in the chloroform/buffer extracts of Salmonella Typhimurium, and to LaL in the extracts of Pseudomonas aeruginosa, suggesting that other lysozyme inhibitors than Ivy exist and are probably widespread in gram-negative bacteria.     

溶氧对变溶菌素发酵的影响

变溶菌素是由球孢链霉菌产生的一种胞外溶菌酶群。它包括几种不同类型的溶菌酶,有着广阔的用途和良好的应用前景。许多研究结果[1,2]表明,它比卵清溶菌酶有更为广泛的溶菌谱,应用范围更广,尤其是在预防和治疗龋齿[3]方面有其独特的优点。在医药上可用作灭菌剂,也可用其作?..     

PlyC, a novel bacteriophage lysin for compartment-dependent proteomics of group A streptococci

Streptococcus pyogenes (Spy) (group A streptococci) is an important and exclusively human bacterial pathogen, which uses secreted and surface-associated proteins to circumvent the innate host defense mechanisms and to adhere and internalize into host cells. Thus, investigation of the bacterial extracellular compartments, including secreted and cell wall-associated subproteomes, is crucial for understanding adherence, invasion, and internalization mechanisms as major steps of Spy pathogenesis. Here, we compared a bacteriophage encoded cell wall hydrolase, PlyC, a multimeric lysin of the C1 bacteriophage, with the established glycosidase, mutanolysin, from Streptomyces globisporus for their suitability to efficiently digest Spy cell walls and release cell wall-anchored Spy proteins for subsequent proteome research. Our results show that PlyC is superior for cell wall protein extraction compared to mutanolysin due to its higher activity and specificity as an N-acetylmuramoyl-L-alanine amidase. Furthermore, our experimental design allowed us to delineate the actual localization of the proteins despite contamination with intracellular proteins.     

Characterization of a major 31-kilodalton peptidoglycan-bound protein of Legionella pneumophila.

A 31-kilodalton (kDa) protein was solubilized from the peptidoglycan (PG) fraction of Legionella pneumophila after treatment with either N-acetylmuramidase from the fungus Chalaropsis sp. or with mutanolysin from Streptomyces globisporus. The protein exhibited a ladderlike banding pattern by autoradiography when radiolabeled [( 35S]cysteine or [35S]methionine) PG material was extensively treated with hen lysozyme. The banding patterns ranging between 31 and 45 kDa and between 55 and 60 kDa resolved as a single 31-kDa protein when the material was subsequently treated with N-acetylmuramidase. Analysis of the purified 31-kDa protein for diaminopimelic acid by gas chromatography revealed 1 mol of diaminopimelic acid per mol of protein. When outer membrane PG material containing the major outer membrane porin protein was treated with N-acetylmuramidase or mutanolysin, both the 28.5-kDa major outer membrane protein and the 31-kDa protein were solubilized from the PG material under reducing conditions. In the absence of 2-mercaptoethanol, a high-molecular-mass complex (100 kDa) was resolved. The results of this study indicate that a 31-kDa PG-bound protein is a major component of the cell wall of L. pneumophila whose function may be to anchor the major outer membrane protein to PG. Finally, a survey of other Legionella species and other serogroups of L. pneumophila suggested that PG-bound proteins may be a common feature of this genus.     

Transformation ofBacillus spp.: An examination of the transformation ofBacillus protoplasts by plasmids pUB110 and pHV33

The protoplasting and transformation techniques described by Chang and Cohen [5] have been modified by the inclusion of mutanolysin and these techniques have been used to prepare protoplasts of a number ofBacillus spp. Cells of some, however, remained resistant to cell wall hydrolysis by both mutanolysin and lysozyme. Protoplasts were prepared from sixBacillus species, including a strain ofB. subtilis, and transformed with the plasmid pUB110. Transformation with the shuttle vector pHV33 was, however, less successful and antibiotic-resistant protoplasts, although detected, either failed to regenerate their osmotic stability or rapidly lost their antibiotic resistance.     

The stability of plasmid pSG 1912 inheritance by the cells of Streptomyces globisporus 1912 and of heterologous streptomycete strains]

Streptomyces globisporus 1912 strain contains plasmid pSG1912 (11, 2kb) determining some phenotypic properties. The plasmid is able to exist and to provide for exhibition of these properties both in autonomous and integrated state. It is established that plasmid pSG1912 and constructed derivatives are stably inherited by cells of S. globisporus 1912 and heterologous hosts, and besides, molecular size and determined properties being retained.     

Sequence of the lyc gene encoding the autolytic lysozyme of Clostridium acetobutylicum ATCC824: comparison with other lytic enzymes

The lyc gene, encoding an autolytic lysozyme from Clostridium acetobutylicum ATCC824, has been cloned. The nucleotide sequence of the lyc gene has been determined and found to encode a protein of 324 amino acids (aa) with a deduced Mr of 34,939. The lyc gene is preceded by two open reading frames with unknown functions, suggesting that this gene is part of an operon. Comparison between the deduced aa sequence of the lyc gene and the directly determined N-terminal sequence of the extracellular clostridial lysozyme suggests that the enzyme is synthesized without a cleavable signal peptide. Moreover, the comparative analyses between the clostridial lysozyme and other known cell-wall lytic enzymes revealed a significant similarity with the N-terminal portion of the lysozymes of Streptomyces globisporus, the fungus Chalaropsis, the Lactobacillus bulgaricus bacteriophage mv1, and the Streptococcus pneumoniae bacteriophages of the Cp family (CPL lysozymes). In addition, the analyses showed that the C-terminal half of the clostridial lysozyme was homologous to the N-terminal domain of the muramoyl-pentapeptide-carboxypeptidase of Streptomyces albus, suggesting a role in substrate binding. The existence of five putative repeated motifs in the C-terminal region of the autolytic lysozyme suggests that this region could play a role in the recognition of the polymeric substrate.