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PubMed1985

[Inactivation of cytochrome P-450 in hydroxylase reactions].

It has been shown that sodium azide, a catalase inhibitor, accelerates the inactivation of cytochrome P-450 in reactions of hydroxylation of type I substrates, e.g., dimethylaniline (DMA), aminopyrine (AP), benzphetamine (BPh), p-nitroanisole (p-Na) and type II substrates--aniline (AN). In the absence of sodium azide, cytochrome P-450 is either non-activated (as in the case of AN) or is inactivated at a low rate. Haemoprotein inactivation in the presence of sodium azide in all hydroxylation reactions with the exception of O-demethylation of p-NA is a first-order reaction with respect to cytochrome P-450. Studies on the mechanism of cytochrome P-450 inactivation demonstrated that hydrogen peroxide formed via the NADPH-dependent hydroxylase cycle exhibits an inactivating effect towards the enzyme. The value of inactivation constant for cytochrome P-450 in hydroxylation reactions proceeding in the presence of sodium azide coincides with that of enzyme inactivation in the NADPH-oxidase and glucose oxidase systems generating H2O2.

Animals↗

PubMed1980

Non-specific binding by macrophages: existence of different adhesive mechanisms and modulation by metabolic inhibitors.

Rat peritoneal cells were made to bind test particles of five different species: immunoglobulin-coated sheep red cells (IGSRC), glutaraldehyde-treated sheep red cells (GSRC), leishmania, latex beads and tumour cells. The dependence of binding on various physicochemical parameters was studied: the binding of latex or leishmania resisted cold (4 degrees), azide, cytochalasin B, ethyleneglycol and dimethylsulphoxide (DMSO). The binding of IGSRC resisted cold and azide, but it was inhibited by cytochalasin B, ethyleneglycol and DMSO. The binding of GSRC was inhibited by cold, azide and ethyleneglycol, but not by cytochalasin B and DMSO. The binding of tumour cells was inhibited by azide, cytochalasin B, ethyleneglycol and DMSO. An attempt was made to saturate selectively some adhesive sites of macrophage membranes: glutaraldehyde-treated bovine albumin (GBSA) inhibited the ingestion of latex and GSRC, not leishmania and IGSRC, whereas a crude leishmania extract (CLE) inhibited the ingestion of all tested particles except latex. Antigen-antibody complexes inhibited the ingestion of IGSRC and leishmania, not latex and GSRC. Rat macrophages were made to bind radio-iodinated GBSA (GIBSA). The uptake of glutaraldehyde-treated albumin was proportional to the amount of substrate the cells were incubated with over a wide concentration range. This uptake was not a result of endocytosis, and it was far more efficient than that of peroxidase. Macrophage-particle interaction was studied with electron microscopy. The binding of IGSRC and leishmania to macrophages involved large areas where the interacting membranes were separated by a low density gap of constant width. The interaction of GSRC and latex with macrophages was much more patchy and irregular. Further, no redistribution of the macrophage surface polysaccharides seemed associated with the binding of GSRC. It was concluded that several different mechanisms and different membrane adhesive structures are involved in non-specific recognition by macrophages. Further, non-specific binding sometimes requires an active cell participation. Several testable hypotheses are described, which suggest further experiments in order to obtain a fuller insight into the mechanism of rosette formation.

Animals↗

PubMed1993

Evaluation of collagen cross-linking techniques for the stabilization of tissue matrices.

The use of glutaraldehyde (GTA) for cross-linking biological tissue implants has a number of undesirable side effects, including cytotoxicity and induction of calcification. In an attempt to find an improved cross-linking agent for tissue implants, we have evaluated a number of cross-linking procedures shown previously to be effective with pure collagen or collagenous substrates, including GTA, succinic anhydride, cyanamide, 1-ethyl-3-(dimethylaminopropyl)carbodi-imide, dimethyl suberimidate, ascorbate-copper, glucose-lysine and acyl azide treatments. Apart from GTA, only acyl azide treatment significantly cross-linked human dermis, the degree of cross-linking being better than that seen after treatment of dermis with 1 mM GTA. Acyl azide treatment of thicker vascular tissue (porcine aorta) also resulted in a significantly cross-linked tissue. Preliminary cytotoxicity studies suggested that acyl azide treatment was not toxic, and, therefore, coupled with its cross-linking ability, this treatment is worthy of further investigation and may prove to be an alternative to GTA for the treatment of bioprostheses.

3T3 Cells↗

PubMed1999

Activation of the human immunodeficiency virus-1 long terminal repeat by respiratory burst oxidants of neutrophils.

The human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) introduced in association with the luciferase reporter gene into Jurkat T cells was strongly activated by a combination of human neutrophils and phorbol myristate acetate (PMA). Activation was not observed when normal neutrophils were replaced by neutrophils which lack a respiratory burst, ie, from a patient with chronic granulomatous disease (CGD), was strongly inhibited by catalase, was potentiated by vanadate, was stimulated by relatively low concentrations of azide, and was inhibited by selective inhibitors of protein kinase C (PKC). The PMA affected activation in three ways: (1) by directly activating the LTR in Jurkat LTRluc; (2) by inducing a respiratory burst in neutrophils with the formation of H2O2; and (3) by increasing the sensitivity of Jurkat LTRluc to the activating effect of H2O2. When PMA was replaced by opsonized zymosan as the neutrophil stimulus, activation of the LTR was low unless azide was added. Activation in the presence of azide was not seen when CGD neutrophils were used or when catalase was added, suggesting that azide acts by inhibiting the degradation of H2O2. These findings indicate that activation of the HIV-1 LTR in Jurkat T cells can be induced by H2O2 released by neutrophils, particularly when PKC is concomitantly activated.

Gene Expression Regulation↗

PubMed1989

Genotoxicity of azidoalanine in mammalian cells.

Sodium azide mutagenesis is mediated through a metabolic intermediate in bacteria and plant species. However, very little is known about the interaction of this intermediate with nucleic acids, its genotoxic potential, or its mechanism of action, especially in mammalian cells. Chinese hamster cells and normal human skin fibroblasts were treated with extracts from Salmonella typhimurium or Hordeum vulgare (barley) containing a crude mutagenic metabolite, as well as with synthetically produced azidoalanine. The cells were evaluated for the induction of sister chromatid exchanges and the ability to perform unscheduled DNA synthesis. With the purified azidoalanine and the azide-treated extracts from Hordeum vulgare, there was a statistically significant increase in the frequency of sister chromatid exchanges observed in both Chinese hamster cells and human fibroblasts. This increase was about twofold, as compared with the control. On the other hand, there was no detectable genotoxic response when cells were exposed to azide-treated extract from Salmonella typhimurium. The results imply that azidoalanine and the crude mutagenic metabolite from Hordeum vulgare are weakly genotoxic in mammalian cells.

Alanine↗

PubMed1997

Mutational analysis of the role of Rap1 in regulating cytoskeletal function in Dictyostelium.

It was shown previously that increased expression of the ras-related rap1 gene in Dictyostelium discoideum altered cell morphology (Rebstein et al., Dev. Genet., 1993, 14, 347-355). Vegetative Rap1 transformants were more flattened and spread than parental Ax2 cells and had increased F-actin near the cell periphery. In addition, Rap1 cells were inhibited in the rapid cell contraction that occurs upon refeeding with nutrient media. In this communication, we show that expression of Rap also markedly reduces the contraction response that occurs upon addition of azide to vegetative cells. The changes in cell morphology, the refeeding contraction response, and the azide contraction response have been used to analyze mutants of Rap1 generated by site-directed mutagenesis. The substitution G12V, predicted to increase the proportion of protein binding GTP, did not alter the effect of Rap on cell morphology or on its ability to inhibit the contraction response to azide, but modestly enhanced the ability of Rap1 to inhibit cell rounding in response to nutrient media. The substitution S17N, predicted to restrict the protein to the GDP-bound state, did not produce the flattened cell morphology and abolished the inhibitory effects of Rap in the two cell contraction assays. These results are consistent with a requirement of GTP binding for the Rap-induced effects. Transformants carrying the Rap-S17N protein had a more polar morphology than the parental Ax2 cells, suggesting the possibility that Rap-S17N interferes with the ability of endogenous Rap to regulate the cytoskeleton. Substitutions at amino acid 38, within the presumptive effector domain, reduced but did not abolish the effects of Rap1 on cell contraction, while the substitution T61Q had no effect on Rap1 activity. Taken together, the results suggest that Rap may have multiple regulatory effects on cytoskeletal function.

Animals↗

PubMed1982

Localization of glycerophosphate acyltransferase in Escherichia coli.

sn-Glycero-3-phosphate acyltransferase (EC 2.3.1.15) the first enzyme involved in phospholipid biosynthesis, is known to be associated with the cytoplasmic membrane of Escherichia coli. The localization of this enzyme in the transverse plane of the membrane was investigated by proteolysis of intact and lysed spheroplasts and by inhibition of glycerol 3-phosphate transport into intact cells in the presence of azide. Glycerophosphate acyltransferase was found to be resistant to proteolysis by trypsin in intact spheroplasts, whereas its enzymatic activity could be destroyed completely by trypsin in lysed spheroplasts. These results are in line with a localization of the acyltransferase at the inner aspect of the cytoplasmic membrane. Sodium azide was shown to have no inhibitory effect on glycerophosphate acyltransferase activity. Lack of incorporation of glycero phosphate into the phospholipids of glycerol phosphate transport-negative cells and inhibition of this incorporation in wild-type and glycerol 3-phosphate transport-constitutive cells by azide support a cytoplasmic-oriented localization of the glycerophosphate acyltransferase.

Acyltransferases↗

PubMed1995

ESR evidence for the generation of reactive oxygen species from the copper-mediated oxidation of the benzene metabolite, hydroquinone: role in DNA damage.

In previous studies, we observed that Cu(II) strongly induces the oxidation of hydroquinone (HQ), producing benzoquinone and H2O2 through a Cu(II)/Cu(I) redox cycle mechanism. The oxidation of HQ by Cu(II) also results in plasmid DNA cleavage. In this study, using ESR spectroscopy we have investigated whether this chemical-metal redox system can generate reactive oxygen species which induce DNA damage. In order to set the stage for the ESR experiments and the inhibitors to be used in these experiments, some preliminary O2 consumption and plasmid DNA cleavage experiments were performed. Mixing 100 microM HQ with 10 microM Cu(II) in phosphate-buffered saline (PBS) resulted in a marked consumption of O2 and the concomitant generation of H2O2, and extensive DNA degradation in chi X-174 RF I DNA. The presence of superoxide dismutase (SOD) or mannitol did not affect either the O2 consumption, H2O2 generation or DNA damage. In contrast, the Cu(I) chelators, bathocuproinedisulfonic acid (BCS) and glutathione (GSH), extensively inhibited the HQ/Cu(II)-mediated O2 consumption and DNA damage. The presence of catalase also prevented the DNA damage. Although the HQ/Cu(II)-mediated O2 consumption increased in the presence of azide, azide markedly inhibited the HQ/Cu(II)-induced DNA degradation, resulting in primarily open circles. Using ESR spectroscopy, it was observed that Cu(II) strongly mediated the formation of semiquinone anion radicals from HQ in PBS, which could be blocked by BCS. alpha-(4-Pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN)-spin trapping experiments showed that the interaction of HQ with Cu(II) produced 4-POBN-CH3 and 4-POBN-CH(OH)CH3 adducts in the presence of dimethyl sulfoxide (DMSO) and ethanol, respectively, suggesting that hydroxyl radical or an equivalent reactive intermediate is generated from the HQ/Cu(II) system. The presence of catalase, BCS or GSH but not SOD completely prevented the formation of 4-POBN-CH3 adduct from the HQ/Cu(II) plus 4-POBN/DMSO system. This indicates that both H2O2 and Cu(I) are critical for the formation of reactive oxygen from the HQ/Cu(II) system. Anaerobic conditions induced an approximately 85% decrease in the formation of 4-POBN-CH3 adduct. Reactive oxygen scavenger experiments showed that the formation of the 4-POBN-CH3 adduct was significantly inhibited by azide but not by mannitol. Overall, the above results indicate that through a copper-redox cycling mechanism the copper-mediated oxidation of HQ generates reactive oxygen species which may participate in DNA damage.

Animals↗

PubMed1984

An investigation of adhesion and detachment in slime mould amoebae using columns of hydrophobic beads.

Vegetative amoebae of Dictyostelium discoideum (strain AX2) adhere to columns of hydrophobic beads (Bio-Beads SM-2) which have been coated with axenic growth medium. This binding is blocked by sodium azide and other inhibitors of aerobic respiration. Bound cells are not detached by lowering the temperature but they can be eluted from the column by including azide in the medium. However, this effect is critically influenced by temperature. The elution profiles become progressively shallower as the temperature is lowered. The profiles represent a set of probability distributions whose means and variances increase with decreasing temperature. Below 20 degrees C, the mean time to cell detachment is a linear function of temperature. A statistical model of this azide-stimulated detachment has been developed which closely predicts the real data. It assumes that each amoeba has k binding sites whose stochastically independent behaviour is governed by a parameter theta; the mean time to detachment of each site is 1/theta. Both parameters have been estimated. The value of k is close to 3 and does not vary with temperature below 20 degrees C. In contrast, theta varies in such a way that the value of 1/theta increases linearly with decreasing temperature, so paralleling the behaviour of the mean cell detachment time.

Adhesiveness↗

PubMed1992

Isolation and characterization of a brefeldin A-resistant mutant of monkey kidney Vero cells.

Brefeldin A (BFA) is a fungal antibiotic which disrupts protein transport between the endoplasmic reticulum and the Golgi. A BFA-resistant mutant of monkey kidney Vero cells, BER-40, which exhibited about a 90-fold increase in the LD50 of BFA (5.2 ng/ml for Vero cells versus 460 ng/ml for BER-40 cells), has been isolated. The increased resistance of BER-40 cells toward BFA was also manifested in a greatly reduced inhibition of protein secretion by BFA in the mutant and a lack of protection by BFA of the mutant cells from ricin cytotoxicity. Somatic cell hybridization between the Vero and BER-40 cells showed that the BFA-resistance in BER-40 behaved as a codominant trait. The structure of the Golgi region, as examined by immunofluorescence microscopy with antibodies against Golgi markers (the 110-kDa protein and mannosidase II) or with fluorescent lipid NBD-ceramide, was unchanged in the mutant cells as compared to that in the wild-type cells. Treatment of Vero cells with BFA (1 micrograms/ml) or with 2-deoxyglucose plus sodium azide resulted in a rapid release of the 110-kDa protein, mannosidase II, and NBD-ceramide from the Golgi membrane to a more diffuse distribution in the cytosol. In contrast, these three Golgi markers remained to be Golgi-associated following treatment of BER-40 cells with BFA or with 2-deoxyglucose plus sodium azide. Immunoblotting of cell extracts from Vero and BER-40 cells with monoclonal antibody against the 110-kDa protein did not reveal any significant difference in the level of this Golgi marker in the mutant cells. These data suggest that the BFA-resistance mutation in BER-40 has rendered the cyclic pathway of the 110-kDa protein assembly to the Golgi membrane resistant to both BFA and 2-deoxyglucose plus sodium azide.

Adenosine Triphosphate↗

PubMed1995

Evidence for SecA- and delta pH-independent insertion of D1 into thylakoids.

Many nuclear-encoded proteins are targeted into chloroplast thylakoids by an azide sensitive Sec-related mechanism or by a delta pH-driven mechanism. In this report, the requirements for the integration of chloroplast-encoded thylakoid proteins have been analysed in pulse-labeled intact chloroplasts. We show that the integration of the photosystem II reaction centre protein, D1, continues in the absence of a delta pH and in the presence of azide. A range of other proteins are similarly targeted to thylakoids in the presence of azide, suggesting that the SecA-related mechanism is not widely used for the targeting of chloroplast-encoded proteins.

Adenosine Triphosphatases↗

PubMed1991

Antimutagenicity of propionic acid bacteria.

The antimutagenic effect of dialysed cell extracts of 4 strains of propionic acid bacteria was examined against the mutagenicity of sodium azide in the TA1535 tester strain of Salmonella typhimurium using the Ames test. It was noted that dialysates of 2 strains of Propionibacterium shermanii, P. pentosaceum and P. acnes, significantly reduced sodium azide-induced revertants. The dialysate of propionic acid cocci did not show an antimutagenic effect. The inhibitory activity was enhanced if the mutagen and extract were coincubated for 20 min prior to performing the mutagenicity assay. Antimutagenicity of dialysates from P. shermanii VKM-103 against MNNG and 9-aminoacridine was shown in S. typhimurium strains TA1535 and TA97. The antimutagenic activity was found in the protein fraction of the cell extract of P. shermanii. The proteins of the dialysate of P. shermanii were separated using a Toyopearl gel column into 3 main peaks according to their molecular weights. The antimutagenic activity towards sodium azide was found in the second and the third peaks. We suggest that dialysates of the cells of propionic acid bacteria contain several kinds of antimutagenic substances with different molecular weights.

Aminacrine↗

PubMed1996

Mutation induction and mutation spectra of S. typhimurium TA100 after exposure to isohistidines.

L-Isohistidine and D,L-isohistidine, but not D-isohistidine, caused an increase of the number of mutant colonies in S. typhimurium strain TA100. Spontaneous and also sodium azide or 2-aminoanthracene induced mutant numbers were enhanced by L-isohistidine and by an isomeric mixture of D,L- and L-isohistidine. These effects could not be attributed to a growth-enhancing property. The colony probe hybridization procedure was used to investigate the effects of the histidines on the spontaneous and azide-induced spectra of the hisG46 allele in strain TA100. D,L-Isohistidine, but not the D-isomer, caused and increase of transitions (CCC-->CTC) and transversions (CCC-->CAC) in the spontaneous spectrum. Sodium azide alone induced a strong increase of CCC-->CTC transitions; combination with the D,L-isohistidine led to a further enhancement of this type of base substitutions, whereas with the L-isomer, no such effect was observed. This supports the hypothesis that the activity of D,L-isohistidine is probably not due to DNA-damaging properties, but rather to indirect mechanisms, such as enhancement of the infidelity of DNA replication and/or interference with DNA-repair or proofreading functions.

Alleles↗

PubMed1990

Effect of polymorphonuclear leukocyte-derived oxygen free radicals and hypochlorous acid on cardiac function and some biochemical parameters.

Polymorphonuclear (PMN) leukocyte activation is known to result in the production and release of oxygen free radicals and hypochlorous acid. Various clinical conditions are associated with PMN leukocyte stimulation. The present investigation deals with the effects of stimulated PMN leukocytes in the absence and in the presence of scavengers of oxygen free radicals (superoxide dismutase, catalase), hypochlorous acid quencher (methionine), and myeloperoxidase inhibitor (azide) on cardiac function and contractility; blood lactate, gases, and pH levels, blood and cardiac tissue malondialdehyde; and PMN leukocyte chemiluminescence activity in anesthetized dogs. Opsonised zymosan was used for stimulation of PMN leukocytes, and the effects were observed for 2 hours. The dogs were divided into four groups: group I, zymosan; group II, superoxide dismutase + catalase + zymosan; group III, methionine + zymosan; group IV, azide + methionine + zymosan. Zymosan produced a decrease in cardiac function and in indices of myocardial contractility and an increase in systemic and pulmonary vascular resistance. There was a decrease in blood pH and in PMN leukocyte chemiluminescense and an increase in the blood lactate and malondialdehyde. Superoxide dismutase plus catalase and methionine reduced the effect of zymosan on cardiac function and contractility and on blood malondialdehyde, lactate, and pH. The combination of azide and methionine did not prevent the deleterious effects of zymosan on cardiac function and contractility. Cardiac tissue malondialdehyde levels were lower in groups III and IV than in groups I and II which had values similar to each other. Methionine was superior to superoxide dismutase plus catalase in the prevention of the deleterious effects of PMN leukocyte stimulation on the various measured parameters. These results suggest that oxygen free radicals and hypochlorous acid are cardiac depressants and increase systemic and pulmonary vascular resistance in addition to causing tissue damage. Clinical situations with PMN stimulation may result in cardiac depression. The oxygen free radical scavenger and hypochlorous acid quencher may be beneficial in the counteraction of the deleterious effects of PMN leukocyte stimulation on the hemodynamic parameters and cellular integrity.

Animals↗

PubMed1996

Relationship between mitochondrial dysfunction and toxicity of propyl gallate in isolated rat hepatocytes.

The relationship between cytotoxicity and mitochondrial dysfunction caused by propyl gallate (PG) has been studied in hepatocytes freshly prepared from fasted rats. Hepatocytes isolated from fasted (18 h) rats were significantly more susceptible to the toxicity of PG than hepatocytes from fed rats. The addition of fructose (15 mM), an alternative carbohydrate source, to hepatocyte suspensions resulted in the prevention of PG (1 mM)-induced cell killing accompanied by decrease in intracellular ATP loss during a 3 h-incubation period. Despite this, fructose did not completely prevent an abrupt loss of intracellular glutathione caused by PG, but effectively inhibited the loss of protein thiol levels. Fructose elicited a concentration (0.5-20mM)-dependent protection against the cytotoxicity of 1.5 mM PG. The incubation of hepatocytes with sodium azide (4 mM), an inhibitor of oxidative phosphorylation, enhanced the toxicity induced by PG (1 mM), but coincubation with fructose delayed the onset of toxicity. Neither azide alone nor fructose plus azide did affect the cell viability during the incubation period. Furthermore, the addition of 2 mM salicylamide, nontoxic to hepatocytes during the incubation period, enhanced PG (1 mM)-induced cytotoxicity and decreased the loss of free PG. These results indicate that the onset of cytotoxicity caused by PG may depend on the intracellular energy status and that mitochondria are critical target for the compound. In addition, the toxicity caused by the inhibition of mitochondrial ATP synthesis is related to the concentration of PG remaining in cell suspensions.

Adenosine Triphosphate↗

PubMed2002

Detailed kinetic analysis and identification of the nucleophile in alpha-L-arabinofuranosidase from Geobacillus stearothermophilus T-6, a family 51 glycoside hydrolase.

alpha-l-Arabinofuranosidases cleave the l-arabinofuranoside side chains of different hemicelluloses and are key enzymes in the complete degradation of the plant cell wall. The alpha-l-arabinofuranosidase from Geobacillus stearothermophilus T-6, a family 51 glycoside hydrolase, was subjected to a detailed mechanistic study. Aryl-alpha-l-arabinofuranosides with various leaving groups were synthesized and used to verify the catalytic mechanism and catalytic residues of the enzyme. The steady-state constants and the resulting Brønsted plots for the E175A mutant are consistent with the role of Glu-175 as the acid-base catalytic residue. The proposed nucleophile residue, Glu-294, was replaced to Ala by a double-base pairs substitution. The resulting E294A mutant, with 4-nitrophenyl alpha-l-arabinofuranoside as the substrate, exhibited eight orders of magnitude lower activity and a 10-fold higher K(m) value compared with the wild type enzyme. Sodium azide accelerated by more than 40-fold the rate of the hydrolysis of 2',4',6'-trichlorophenyl alpha-l-arabinofuranoside by the E294A mutant. The glycosyl-azide product formed during this reaction was isolated and characterized as beta-l-arabinofuranosyl-azide by (1)H NMR, (13)C NMR, mass spectrometry, and Fourier transform infrared analysis. The anomeric configuration of this product supports the assignment of Glu-294 as the catalytic nucleophile residue of the alpha-l-arabinofuranosidase T-6 and allows for the first time the unequivocal identification of this residue in glycoside hydrolases family 51.

Alanine↗

PubMed1990

Synergy between penicillin and gentamicin against enterococci.

The role of active uptake in aminoglycoside activity against penicillin-treated enterococci was studied by viable counts and ATP determinations. Penicillin and gentamicin gave synergistic bactericidal and post-antibiotic effects (PAEs) which were partially reduced by sodium azide, an electron transport inhibitor, and totally blocked in the presence of both sodium azide and EDTA, which chelates divalent cations. EDTA and gentamicin showed marked synergy in both 'killing curve' and PAE experiments. This synergy was completely inhibited by sodium azide. The data indicate that the activity of gentamicin against enterococci that have been damaged by penicillin or EDTA is energy-dependent. This is consistent with present theories of gentamicin uptake via transportation drive by a protonmotive force.

Adenosine Triphosphate↗

PubMed1993

The filamentous bacteriophage assembly proteins require the bacterial SecA protein for correct localization to the membrane.

The noncapsid assembly proteins pI and pI of the filamentous bacteriophage f1 are inserted into the inner membrane of Escherichia coli via an internal signal sequence. Inhibition of the activity of SecA with low concentrations of sodium azide results in rapid accumulation of pI and pI proteins in the cytoplasm. However, both proteins are inserted into the membrane under the same conditions when synthesized in bacteria containing a secA azide resistance mutation. The other noncapsid assembly protein, pIV, is an outer membrane protein synthesized with a cleavable signal sequence. Wild-type bacteria accumulate the precursor to pIV when protein synthesis is in the presence of low concentrations of sodium azide. These results suggest that the f1 bacteriophage assembly proteins require SecA and consequently the bacterial Sec system to reach their proper membrane location.

Adenosine Triphosphatases↗