ε-聚赖氨酸对阪崎克罗诺杆菌细胞结构与生物被膜形成的影响北大核心CSCD

ε-聚赖氨酸(ε-polylysine,ε-PL)作为一种抗菌活性强、安全性高、热稳定性好的阳离子型天然多肽,已作为安全的食品防腐剂受到关注。以阪崎克罗诺杆菌(Cronobacter sakazakii)为供试菌株,揭示ε-PL的抑菌机理,为细菌耐药性和食品防腐措施研究提供理论支持。研究了ε-PL作用下对阪崎克罗诺杆菌的最小抑菌浓度(minimum inhibitory concentration,MIC)、细胞膜壁通透性、细胞表面疏水性及运动性等生理特性的影响,并利用透射电子显微镜对ε-PL作用下的细菌细胞形态变化进行了观察,在此基础上,探究了ε-PL对阪崎克罗诺杆菌生物被膜(biofilm,BF)的抑制和清除作用效果,并利用荧光染色显微观察清除后被膜菌通透性的改变。ε-PL对阪崎克罗诺杆菌的抑菌活性具有浓度依赖性,ε-PL对阪崎克罗诺杆菌ATCC51329的MIC为256 μg/mL。ε-PL能够增强细胞膜壁通透性,使其细胞内容物如核酸、碱性磷酸酶等大量渗出,从而表现对阪崎克罗诺杆菌的杀菌作用。同时ε-PL能够降低阪崎克罗诺杆菌的表面疏水性和运动性,进而影响阪崎克罗诺杆菌生物被膜的形成。ε-PL对阪崎克罗诺杆菌生物被膜抑制和清除的作用效果显著,结合物理振荡,可大大提高生物被膜清除效率。ε-PL能够破坏阪崎克罗诺杆菌的细胞结构,从而达到抑菌效果。ε-PL能够降低阪崎克罗诺杆菌细胞表面的疏水性、运动性,进而ε-PL能够抑制生物被膜的形成,对成熟生物被膜也具有清除作用。     

黄芩苷对阪崎克罗诺杆菌生物膜的抑制作用

【目的】分析黄芩苷对阪崎克罗诺杆菌生物膜的抑制作用。【方法】采用XTT法评价黄芩苷对阪崎克罗诺杆菌起始粘附性及生物膜内细菌细胞活性的影响,并且采用荧光实时定量PCR(Quantitative real-time PCR,q RT-PCR)检测了阪崎克罗诺杆菌生物膜相关基因glp Q、nlp D、gsi B、deo B、lux S、sdi A的表达水平。【结果】黄芩苷对阪崎克罗诺杆菌的抑制效果呈剂量依赖型。黄芩苷对阪崎克罗诺杆菌的MIC80值为1 024 mg/L,该浓度的黄芩苷对阪崎克罗诺杆菌BAA-894和IQCC10423菌株生物膜的抑制率分别为83.7%和53.2%。浓度为2 048 mg/L的黄芩苷能够通过降低阪崎克罗诺杆菌的粘附性来抑制新生物膜的形成。另外,实时定量PCR结果表明黄芩苷可能通过下调阪崎克罗诺杆菌生物膜相关基因的表达来抑制其生物膜的形成。【结论】黄芩苷有可能被作为抗菌剂以预防和灭活阪崎克罗诺杆菌生物膜。     

枯草芽孢杆菌中bacilosarcin B对美人鱼发光杆菌的抑菌机理

【背景】美人鱼发光杆菌(Photobacteriumdamselae)是一种海洋条件致病菌,能够引起多种海洋生物和人类疾病。因此,探究美人鱼发光杆菌的生物防治技术具有重要意义。【目的】探究枯草芽孢杆菌(Bacillus subtilis)中bacilosarcin B对美人鱼发光杆菌的抑菌活性及其可能的抑菌机理。【方法】利用高效液相色谱法从枯草芽孢杆菌fmb60发酵液中制备bacilosarcin B,采用分光光度法测定bacilosarcinB对多种致病菌的最小抑菌浓度及其对美人鱼发光杆菌的时间-抑菌曲线。测定bacilosarcin B对美人鱼发光杆菌生物被膜、胞外核酸、蛋白质和胞内碱性磷酸酶含量的影响,结合荧光显微镜、扫描电镜和透射电镜检测美人鱼发光杆菌细胞膜通透性和细胞壁完整性,并研究bacilosarcin B对细菌运动能力和胞内DNA的作用。【结果】Bacilosarcin B对美人鱼发光杆菌最小抑菌浓度为8μg/mL。抑菌机理研究表明bacilosarcin B通过破坏细菌细胞壁和细胞膜的完整性使细胞膜通透性增强,造成细胞内成分渗出。此外,bacilosarcinB还可与...     

阪崎克罗诺杆菌噬菌体JC01的筛选和特性

【背景】阪崎克罗诺杆菌是一种食源性病原体,摄入受污染的婴儿配方奶粉(powdered infant formula, PIF)常引起新生儿坏死性小肠结肠炎和脑膜炎,对早产儿和免疫功能低下的婴儿健康甚至生命产生严重威胁。噬菌体具有特异性杀菌性,可成为一种新型生物防控制剂预防阪崎克罗诺杆菌和其他食源性致病菌的污染。【目的】从污水中分离出感染阪崎克罗诺杆菌噬菌体,评价其生物学特性、基因组生物信息及在婴儿配方奶粉中杀菌作用。【方法】采用双层琼脂法分离鉴定噬菌体,并测定其酸碱稳定性、温度稳定性、宿主范围和一步生长曲线,透射电镜观察形态,对其基因组进行二代测序和裂解功效测定。【结果】从污水中分离到一株新的能裂解阪崎克罗诺杆菌的噬菌体JC01,具有二十面立体对称头部和非收缩的长尾,噬菌体JC01基因组为双链DNA,由61 736 bp组成,预测有76个开放阅读框(open reading frame, ORF),不含有tRNA,基因组中不含有耐药基因和毒力基因。系统发育分析及基因比对分析显示噬菌体JC01是全新的噬菌体,归类于有尾噬菌体纲(Caudoviricetes)卡金斯病毒科(Casjensviridae)雅昆病毒属(Jacunavirus),被命名为Jacunavirus 01。噬菌体JC01在不同温度(−20-40 °C)和pH 5.0-9.0范围内稳定,且对婴儿配方奶粉污染的阪崎克罗诺杆菌具有良好的杀菌效果。【结论】JC01噬菌体是裂解阪崎克罗诺杆菌的新噬菌体,作为生物安全防控剂在食品生产和加工方面具有很大潜力。     

Plantaricin 163对热杀索丝菌的抗菌活性及其作用机制

【背景】热杀索丝菌(Brochothrix thermosphacta)为鲫鱼在4°C贮藏过程中的主要腐败菌,Plantaricin 163是由植物乳杆菌产生的一种新型广谱细菌素,能明显延长鲫鱼的贮藏期。【目的】研究Plantaricin163对热杀索丝菌的抗菌活性和作用机制。【方法】通过测定最小抑菌浓度(Minimuminhibitoryconcentration)和杀菌动力学了解Plantaricin163对热杀索丝菌的抗菌效果,并从电导率的变化、核酸和蛋白的泄露、流式细胞实验、扫描电镜和透射电镜观察等4个方面探讨Plantaricin 163对热杀索丝菌的作用机制。【结果】Plantaricin 163对热杀索丝菌的的最小抑菌浓度为32μg/mL,优于Nisin的作用效果,作用方式为杀菌模式,6 h内能完全杀死热杀索丝菌。Plantaricin163能够通过增加热杀索丝菌细胞膜的通透性,增加胞外电导率,进而破坏细胞膜完整性,导致内容物泄漏,并影响细胞的外部形态和内部结构,从而导致菌体细胞瓦解死亡。【结论】Plantaricin 163可以破坏热杀索丝菌的细胞膜和内部结构,发挥抗菌活性。     

短双歧杆菌对鼠伤寒沙门氏菌的抑制

【背景】鼠伤寒沙门氏菌是主要的肠道病原菌之一,利用益生菌治疗肠道病原菌感染已成为一种新型、绿色的微生态疗法。【目的】研究筛选出的短双歧杆菌无细胞发酵上清液(Cell-free supernatant,CFS)对鼠伤寒沙门氏菌的体外抑制作用及机制。【方法】采用微量稀释法测定短双歧杆菌YH68 CFS对鼠伤寒沙门氏菌的最小抑菌浓度(Minimum inhibitory concentration,MIC)和亚抑制浓度(Sub-inhibitory concentrations,SIC),并从鼠伤寒沙门氏菌的细胞形态、细胞膜通透性、膜完整性以及毒力基因表达的变化探讨YH68 CFS对鼠伤寒沙门氏菌的抑菌机理,同时检测YH68 CFS对鼠伤寒沙门氏菌粘附和侵袭肠上皮细胞HT29的影响。【结果】YH68 CFS (3×109 CFU/mL)对鼠伤寒沙门氏菌具有较好的抑制效果,抑菌圈直径为22.27±0.44 mm,最小抑菌浓度为250μL/mL,对鼠伤寒沙门氏菌的抑制机制是通过增加其细胞膜通透性破坏其完整性,形成难以修复的孔洞,最终达到抑菌的目的;亚抑制浓度为62.5μL/mL时YH68 CFS并不能影响鼠伤寒沙门氏菌的生长,但仍然能通过下调毒力基因表达的方式抑制其对肠上皮细胞的粘附和入侵。【结论】短双歧杆菌YH68对鼠伤寒沙门氏菌具有良好的抑菌作用,可作为治疗沙门氏菌感染的潜在益生菌。     

阪崎克罗诺杆菌的16S rDNA鉴定分型

阪崎克罗诺杆菌（Cronobacter sakazakii）是一种重要的食源性条件致病菌,易引发新生儿、早产儿、低体重新生儿和免疫力低下的婴幼儿产生严重的脑膜炎、菌血症和坏死性小肠结肠炎。本研究以分离自不同来源、通过生化鉴定的37株阪崎克罗诺杆菌作为研究对象,利用16S rDNA基因测序的方法对阪崎克罗诺杆菌进行鉴定和分型。结果表明：ES4并非为阪崎克罗诺杆菌,说明采用16S rDNA基因测序进行阪崎克罗诺杆菌的鉴定更为可靠;通过构建系统发育树分析,分离菌株位于同一系统发育分支;根据序列同源性比对,可将这一分支下的所有菌株分成7个子群,这表明16S rDNA基因测序可以对阪崎克罗诺杆菌进行分型,进一步揭示其系统发育关系。     

益生菌拮抗阪崎肠杆菌的初步研究

目的研究鼠李糖乳杆菌和植物乳杆菌等8种常见益生菌对阪崎肠杆菌的拮抗作用。方法采用牛津杯法测定益生菌耗尽上清对阪崎肠杆菌的抑菌圈,获得对阪崎肠杆菌具有较强抑菌能力的鼠李糖乳杆菌和植物乳杆菌;采用混合培养法对2株益生菌与阪崎肠杆菌的拮抗竞争能力进行测试。结果 8种益生菌耗尽上清均能抑制阪崎肠杆菌,其抑菌能力具有热稳定性且依赖于酸性pH环境。阪崎肠杆菌(107CFU/mL)与鼠李糖乳杆菌(108CFU/mL或109CFU/mL)共孵育至24 h,其活菌量开始逐渐下降,至120 h孵育结束下降到105CFU/mL;菌量比为1:10的阪崎肠杆菌与植物乳杆菌共孵育至24 h,其活菌量开始逐渐下降,菌量比为1:100时则提前至8 h,至120 h孵育结束活菌量均下降到102CFU/mL。结论鼠李糖乳杆菌和植物乳杆菌均能有效地竞争拮抗阪崎肠杆菌。     

甘氨酸受体在肾细胞缺氧保护中的作用研究

目的明确甘氨酸受体(glycine receptor,GlyR)是否介导甘氨酸对ATP耗竭细胞的保护作用。方法构建甘氨酸受体α1亚单位(GlyRα1)的真核表达载体pcDNA3.1(b),转染入缺乏天然GlyR的人胚胎肾细胞HEK293。化学性缺氧使细胞处于ATP耗竭状态,光学显微镜及电镜观察细胞形态及超微结构改变,LDH释放率、细胞膜对荧光标记复合物通透性反映细胞膜完整性,台盼蓝染色观察细胞活性。结果细胞ATP耗竭3h后,细胞膜通透性明显增加,细胞器结构损伤,大量细胞死亡。甘氨酸明显降低表达GlyR的转染HEK293细胞膜通透性,阻止荧光标记复合物进入细胞内,细胞LDH释放率由59.18±8.10%下降为35.15±2.61%。从而维持细胞形态结构,降低细胞死亡率。对不表达GlyR细胞无保护作用。结论GlyR介导甘氨酸对ATP耗竭细胞的保护作用,增强细胞对ATP耗竭的耐受能力,增加细胞的存活几率。     

蝎毒多肽Ctry2459抗白色念珠菌机制研究

【目的】探究蝎毒多肽Ctry2459抗白色念珠菌的作用机制。【方法】采用肉汤稀释法并结合平板计数法测定蝎毒多肽Ctry2459对白色念珠菌的最小抑菌浓度和最小杀真菌浓度;通过平板计数法绘制蝎毒多肽Ctry2459对白色念珠菌的时间-杀菌动力学曲线;通过PI吸收实验检测蝎毒多肽Ctry2459对白色念珠菌细胞膜完整性的影响;通过核酸阻滞实验检测蝎毒多肽Ctry2459与核酸间是否具有结合作用;通过流式细胞技术检测蝎毒多肽Ctry2459对白色念珠菌活性氧、线粒体膜电位以及凋亡/坏死的影响。【结果】蝎毒多肽Ctry2459对白色念珠菌的最小抑菌浓度和最小杀真菌浓度分别为25μg/mL和50μg/mL。蝎毒多肽Ctry2459对白色念珠菌的杀菌作用具有时间和浓度依赖性,并可通过直接破坏细胞膜的完整性以及通过ROS介导的线粒体失能导致细胞坏死的方式杀灭白色念珠菌细胞。【结论】蝎毒多肽Ctry2459可以作为抗白色念珠菌药物研发的候选分子或者分子模板。     

Class III bacteriocin Helveticin-M causes sublethal damage on target cells through impairment of cell wall and membrane

Helveticin-M, a novel Class III bacteriocin produced by Lactobacillus crispatus exhibited an antimicrobial activity against Staphylococcus aureus, S. saprophyticus, and Enterobacter cloacae. To understand how Helveticin-M injured target cells, Helveticin-M was cloned and heterologously expressed in Escherichia coli. Subsequently, the cell wall organization and cell membrane integrity of target cells were determined. The mechanism of cellular damage differed according to bacterial species. Based on morphology analysis, Helveticin-M disrupted the cell wall of Gram-positive bacteria and disorganized the outer membrane of Gram-negative bacteria, therefore, altering surface structure. Helveticin-M also disrupted the inner membrane, as confirmed by leakage of intracellular ATP from cells and depolarization of membrane potential of target bacteria. Based on cell population analysis, Helveticin-M treatment caused the increase of cell membrane permeability, but the cytosolic enzymes were not influenced, indicating that it was the sublethal injury. Therefore, the mode of Helveticin-M action is bacteriostatic rather than bactericidal.     

ATP analogues induce membrane permeabilization in transformed mouse fibroblasts

The mechanism underlying ATP-induced permeabilization of transformed mouse fibroblasts was studied by using nonhydrolyzable analogues of ATP. Incubation of 3T6 cells with 0.6 mM of either ATP, 5'-adenylyl imidodiphosphate (p[NH]ppA) or adenosine 5'-[beta, gamma-methylene]triphosphate (p[CH2]ppA) resulted in an increase of 17-, 8- or 5-times, respectively, in the cell membrane permeability, measured by the efflux of normally impermeant metabolites from the cells. The induced cell permeabilization was preceded by a reduction in the membrane potential (delta psi), determined according to the distribution of the cation tetraphenylphosphonium (TPP+) between the cells and the medium. Reduction of 26, 18 and 13 mV in delta psi was exerted by 0.6 mM of either ATP, p[NH]ppA or p[CH2]ppA, respectively. In 3T3 cells the untransformed counterparts of 3T6 cells, neither reduction of delta psi, nor alterations in membrane permeability were exerted by either ATP or by its analogues. The data indicate that the dissociation of the beta, gamma-phosphate bond is not essential for membrane permeabilization by external ATP, implying that the binding of ATP to the cell surface of transformed cells is sufficient to initiate the permeabilization process. The data also suggest that delta psi is involved in the control of membrane permeability.     

Comparative antimicrobial activity and mechanism of action of bovine lactoferricin-derived synthetic peptides

Lactoferricin B (LfcinB), a 25 residue peptide derived from the N-terminal of bovine lactoferrin (bLF), causes depolarization of the cytoplasmic membrane in susceptible bacteria. Its mechanism of action, however, still needs to be elucidated. In the present study, synthetic LfcinB (without a disulfide bridge) and LfcinB (C–C; with a disulfide bridge) as well as three derivatives with 15-, 11- and 9-residue peptides were prepared to investigate their antimicrobial nature and mechanisms. The antimicrobial properties were measured via minimum inhibitory concentration (MIC) determinations, killing kinetics assays and synergy testing, and hemolytic activities were assessed by hemoglobin release. Finally, the morphology of peptide-treated bacteria was determined by atomic force microscopy (AFM). We found that there was no difference in MICs between LfcinB and LfcinB (C–C). Among the derivatives, only LfcinB15 maintained nearly the same level as LfcinB, in the MIC range of 16–128 μg/ml, and the MICs of LfcinB11 (64–256 μg/ml) were 4 times more than LfcinB, while LfcinB9 exhibited the lowest antimicrobial activity. When treated at MIC for 1 h, many blebs were formed and holes of various sizes appeared on the cell surface, but the cell still maintained its integrity. This suggested that LfcinB had a major permeability effect on the cytoplasmic membrane of both Gram-positive and Gram-negative bacteria, which also indicated it may be a possible intracellular target. Among the tested antibiotics, aureomycin increased the bactericidal activity of LfcinB against E. coli, S. aureus and P. aeruginosa, but neomycin did not have such an effect. We also found that the combination of cecropin A and LfcinB had synergistic effects against E. coli.     

XRE家族转录因子XrpA调控粘质沙雷氏菌的耐酸能力

【背景】工业菌株的耐酸能力是发酵过程中的一大挑战。粘质沙雷氏菌(Serratia marcescens)作为肠杆菌科的一种细菌,可生成2,3-丁二醇、乙偶姻和灵菌红素等高附加值产品。然而目前对于粘质沙雷氏菌酸耐受能力的分子机制尚不清楚。【目的】通过对转录调控因子XrpA的挖掘以及对其功能的研究,探究粘质沙雷氏菌酸耐受能力的分子机制,为改善工业菌株耐酸能力提供新的策略。【方法】通过对粘质沙雷氏菌进行转座子插入突变,构建了一个Tn5G转座子插入突变文库,利用文库筛选了一株酸敏感型突变株,并对其进行测序鉴定;同时还对突变菌株中与耐酸相关关键基因的转录水平以及细胞膜通透性、细胞膜完整性和H+-ATPase的活性变化进行检测。【结果】发现了一个响应酸胁迫的转录调控因子BVG90₂3400,其属于XRE超级家族转录调控因子,命名为XrpA。在酸性条件下,与野生型菌株(JNB5-1)相比,xrpA被阻断后导致了粘质沙雷氏菌多种表型的变化,其中包括生物量显著下降、H+-ATPase活性降低、细胞膜的通透性以及完整性受到破坏。【结论】XrpA影响粘质沙雷氏菌耐酸能力的分子机制是通过...     

Cellular responses to external ATP which precede an increase in nucleotide permeability in transformed cells

Transformed mouse fibroblasts, such as 3T6, exhibit an increase in plasma membrane permeability to nucleotides and other normally impermeant molecules when incubated with external ATP in an alkaline medium low in divalent cations. Increased nucleotide permeability, induced by external ATP, occurs after a 3- to 5-min lag period. Prior to this event, there is a dramatic Na+ influx and K+ efflux, a significant reduction in the levels of intracellular ATP and organic phosphates, and a reduction in the plasma membrane potential. Accordingly, we postulate that these cellular responses to external ATP play a role in the efflux of nucleotides. Ouabain, a specific inhibitor of the plasma membrane (Na+,K+)-ATPase, acts together with low concentrations of external ATP to increase nucleotide permeability in 3T6 cells. This effect occurs at concentrations of ouabain and ATP which alone do not increase nucleotide permeability. In addition, ouabain and low concentrations of ATP alone have little effect on the level of intracellular ATP. This is in contrast to energy inhibitors and uncouplers which appear to enhance nucleotide permeability by lowering the intracellular ATP concentration. Ouabain alone causes a threefold increase in intracellular Na+ levels and a similar reduction in intracellular K+ levels under our experimental conditions, supporting the idea that ion fluxes are involved in the mechanism of permeabilization.     

Ethanol reduces mitochondrial membrane integrity and thereby impacts carbon metabolism of Saccharomyces cerevisiae

Saccharomyces cerevisiae is an excellent ethanol producer, but is rather sensitive to high concentration of ethanol. Here, influences of ethanol on cellular membrane integrity and carbon metabolism of S.?cerevisiae were investigated to rationalize mechanism involved in ethanol toxicity. Addition of 5% (v/v) ethanol did neither significantly change the permeability of the cytoplasmic membrane of the reference strain S.?cerevisiae BY4741 nor of the ethanol-tolerant strain iETS3. However, the addition of ethanol resulted in a marked decrease in the mitochondrial membrane potential and in increased concentrations of intracellular reactive oxygen species (ROS). The carbon flux was redistributed under these conditions from mainly ethanol production to the TCA cycle. This redistribution was possibly a result of increased energy demand for cell maintenance that increased from about zero to 20-40?mmol?ATP?(g(CDW) h)(-1) . This increase in maintenance energy might be explained by the ethanol-induced reduction of the proton motive force and the required removal of ROS. Thus, the stability of the mitochondrial membrane and subsequently the capacity to keep ROS levels low could be important factors to improve tolerance of S.?cerevisiae against ethanol.     

Inhibitory effect of a lipopeptide biosurfactant produced by Bacillus subtilis on planktonic and sessile cells of Trichosporon spp.

The present study aimed to investigate the inhibitory effect of a bacterial biosurfactant (TIM96) on clinical strains of Trichosporon. Additionally, the effect of TIM96 on the ergosterol content, cell membrane integrity, and the hydrophobicity of planktonic cells was assessed. The inhibitory activity of TIM96 against Trichosporon biofilms was evaluated by analyzing metabolic activity, biomass and morphology. MIC values ranged from 78.125 to 312.5 μg ml^?1 for TIM96; time-kill curves revealed that the decline in the number of fungal cells started after incubation for 6 h with TIM96 at both MIC and 2×MIC. The biosurfactant reduced the cellular ergosterol content and altered the membrane permeability and the surface hydrophobicity of planktonic cells. Incubation at 10×MIC TIM96 reduced cell adhesion by up to 96.89%, thus interfering with biofilm formation. This concentration also caused up to a 99.2% reduction in the metabolic activity of mature biofilms. The results indicate potential perspectives for the development of new antifungal strategies.     

复合生物保鲜剂对松鼠葡萄球菌的抑菌性能及其作用机理研究

以冷藏带鱼中分离出的革兰氏阳性优势菌——松鼠葡萄球菌(Staphylococcus sciuri)为试验菌,研究复合生物保鲜剂(配比浓度为:壳聚糖10.0 g/L,溶菌酶0.3 g/L与茶多酚3.0 g/L)对松鼠葡萄球菌的抑菌效果与作用机理。通过牛津杯法确定复合保鲜剂对松鼠葡萄球菌的最小抑菌浓度(MIC)与最小杀菌浓度(MBC),结合抑菌活力、细菌生长曲线、碱性磷酸酶(AKP)活性、细胞膜完整性、膜通透性与细菌超微结构观察等,综合评价不同浓度复合保鲜剂在不同处理时间内对松鼠葡萄球菌的作用效果。结果表明,复合保鲜剂对松鼠葡萄球菌的MIC与MBC分别为0.8与1.6 mg/mL,随着处理时间的延长,复合生物保鲜剂明显抑制松鼠葡萄球菌的生长,使菌体细胞外的AKP量增多,造成细菌菌体细胞壁通透性增大,细胞结构的完整性受到破坏,菌液电导率值显著升高,菌体电解质等内容物外泄,影响细胞内环境和细胞膜的稳定性,菌体皱缩变形,表面粗糙,细胞壁塌陷,细胞质外泄渗出,导致菌体死亡。     

ATP analogues induce membrane permeabilization in transformed mouse fibroblasts

The mechanism underlying ATP-induced permeabilization of transformed mouse fibroblasts was studied by using nonhydrolyzable analogues of ATP. Incubation of 3T6 cells with 0.6 mM of either ATP, 5′-adenylyl imidodiphosphate (p[NH]ppA) or adenosine 5′-[β,γ-methylene]triphosphate (p[CH₂]ppA) resulted in an increase of 17-, 8- or 5-times, respectively, in the cell membrane permeability, measured by the efflux of normally impermeant metabolites from the cells. The induced cell permeabilization was preceded by a reduction in the membrane potential (Δψ), determined according to the distribution of the cation tetraphenylphosphonium (TPP⁺) between the cells and the medium. Reduction of 26, 18 and 13 mV in Δψ was exerted by 0.6 mM of either ATP, p[NH]ppA or p[CH₂]ppA, respectively. In 3T3 cells the untransformed counterparts of 3T6 cells, neither reduction of Δψ, nor alterations in membrane permeability were exerted by either ATP or by its analogues. The data indicate that the dissociation of the β,γ-phosphate bond is not essential for membrane permeabilization by external ATP, implying that the binding of ATP to the cell surface of transformed cells is sufficient to initiate the permeabilization process. The data also suggest that Δψ is involved in the control of membrane permeability.