Expression of the Serratia marcescens lipoproteins gene in Escherichia coli

The lipoprotein gene (lpp) of Serratia marcescens was cloned in a lambda phage vector (K. Nakamura and M. Inouye, Proc. Natl. Acad. Sci. U.S.A. 77: 1369-1373, 1980). This lpp gene was recloned in plasmid vectors pBR322 and pSC101. When a lipoprotein-deficient (lpp) mutant of Escherichia coli was transformed with pBR322 carrying the S. marcescens lpp gene, cells became nonleaky for ribonuclease, resistant to ethylenediaminetetraacetic acid, and sensitive to globomycin. The lipoprotein was found exclusively in the outer membrane fraction. These results indicate that the S. marcescens lipoprotein was normally secreted across the cytoplasmic membrane, modified, and assembled in the E. coli outer membrane. The amount of the free-form lipoprotein produced in this system was three times higher than that produced in lpp + C. coli cells, whereas there was no difference in the amount of the bound-form lipoprotein. On the other hand, lpp E. coli cells which harbored pSC101 carrying the S. marcescens lpp gene produced only one-third of the free-form lipoprotein produced in lpp E. coli cells which harbored pSC101 carrying the E. coli lpp gene. One of the major factors causing this difference in efficiency of gene expression between the lpp genes of S. marcescens and E. coli appears to be a deletion mutation at the transcription termination region found in the cloned S. marcescens lpp gene. The functional half-life of the S. marcescens lpp messenger ribonucleic acid in E. coli was found to be found half that of the E. coli lpp messenger ribonucleic acid.

Persistence of chlamydial infection after treatment for neonatal conjunctivitis

A high incidence of pharyngeal infection was found in babies with isolation-positive chlamydial conjunctivitis. Chlamydia trachomatis was isolated from the pharynx of 12 (52%) of 23 babies before treatment, and was reisolated from the eyes of 4 (12%) of 34 and from the pharynx of 14 (41%) of 34 after treatment. C trachomatis was reisolated significantly more often from babies treated only with topical tetracycline for 4 weeks (75%) than from those treated with both topical tetracycline and oral erythromycin for 2 weeks (32%). Reisolation from the eyes was associated with only minor clinical signs. Radiological signs of an inflammatory lesion in the chest were found in 2 of 8 babies examined because of persistent cough. These signs were not associated with high or rising titres of serum chlamydial antibody.

The araC gene of Escherichia coli: transcriptional and translational start-points and complete nucleotide sequence

The nucleotide sequence of the Escherichia coli araC gene and flanking regions have been determined from a series of overlapping fragments using the technique of base-specific chemical cleavage of Maxam and Gilbert (1980). The nucleotide sequence of araC gene was confirmed by the partial amino acid sequences of araC protein and its methionine peptides. The primary structure of araC polypeptide consists of 291 amino acid residues, giving it a chemical molecular weight of 33 314 daltons. The transcriptional start-point has been deduced from the sequence of araC mRNA synthesized in vitro and in vivo, and it is located 148 bp away from the transcriptional start-point of the araBAD operon. The translational start-point for the araC gene was deduced from the N-terminal amino acid sequence of the protein, and is located 165 bp from the 5'-end of araC mRNA. There is, therefore, a leader sequence of 164 bp preceding the araC gene.

Partial characterization of the atypical creatine kinase isoenzyme fraction in three cases

The atypical creatine kinase isoenzyme fraction in the sera of three patients was studied utilizing the technic of crossed immunoelectrophoresis. The findings provide strong evidence that in these clinically unrelated patients the atpical isoenzyme fraction is a complex of creatine kinase and IgG.

Visual loss caused by corneal crystals in myeloma: rapid improvement and plasma exchange and chemotherapy

Recognition of needle-like crystals in the cornea of a patient with deteriorating visual acuity initiated laboratory studies which demonstrated underlying multiple myeloma. Crystal deposition in the cornea occurs only rarely in multiple myeloma, and evidently reflects an unusual tendency for certain paraproteins to form numerous small aggregates which are deposited particularly within, and between, corneal epithelial cells. Treatment with chemotherapy, plus repeated plasma exchange with a normal plasma protein product resulted in significant depletion of crystals, and improvement in visual acuity over a period of three weeks. Accelerated clearance of paraprotein by plasmapheresis appeared to contribute materially to the rapidity of recovery, since recovery was considerably faster than in reported cases where treatment was with chemotherapy alone.

Cholesterol levels and plasma membrane fluidity in 3T3 and SV101-3T3 cells

Polyene antibiotics such as filipin selectively inhibit wheat germ agglutinin-induced agglutination of transformed and malignant cells compared to normal cells (Hatten ME, Burger MM: Biochemistry 18: 739, 1979). Since filipin binds specifically to cholesterol, we measured cholesterol levels in 3T3 cells and SV101-3T3 cells. SV101-3T3 cells contained 50-100% more cholesterol per cell than 3T3 cells. Both cell types were starved for cholesterol by growth in lipid-depleted medium plus 25-hydroxycholesterol. The cholesterol level of SV101-3T3 cells decreased by 30-50%, while the level in 3T3 cells remained constant. Filipin-stained SV101-3T3 cells revealed bright patches of filipin under fluorescence microscopy. These patches were absent in 3T3 cells and in SV101-3T3 and 3T3 cells starved for cholesterol. We selectively labeled plasma membranes of these cells with a spin label analog of phosphatidylcholine. The spin label indicated differences in plasma membrane fluidity that may be related to the different cholesterol levels in 3T3 and SV101-3T3 cells.

Modulation of sensitivity to natural killer cell lysis after in vitro explantation of a mouse lymphoma

On the basis of studies indicating that natural killer (NK) cells of the mouse can selectively kill certain syngenetic, allogeneic, and xenogeneic tumor cells in short-term Cr release assays and that cell lines established in vitro are more sensitive than the corresponding ascites tumor cells passaged in vivo, the kinetics of the modulation to increased sensitivity was studied after in vitro explanation of the A/Sn mouse-derived YAC ascites lymphoma. Sensitivity to NK lysis appeared after 3 weeks of culturing and reached the level of the continuously cultured line after 2 months. With the more sensitive competition assay, a change could be demonstrated as early as 2--24 hours of culture. The expression of the Moloney murine leukemia virus-determined, cell-surface antigen, measured by quantitative absorption with intact cells, increased in parallel with the NK sensitivity. In contrast, the H-2 alloantigen concentration decreased during in vitro culture.

Calibration of mass spectrometers for van der Waals dimers

A stream tube from a small supersonic free jet in vacuo is passed successively through the ion source of a quadrupole mass spectrometer and into an enclosed ionization gauge which indicates total mass flux. By simultaneous measurements of dimer and monomer ion currents as well as total mass flux we are able to arrive at absolute values of the relative concentration of neutral monomer and dimer in the free jet. Results obtained with argon, carbon dioxide, and oxygen indicate substantial fragmentation of dimers in the ion source. Consequently, populations of neutral dimers in supersonic free jets of the kind widely used as beam sources may be much larger than previous studies have indicated.

Further studies on the relationship between large glycoprotein molecules and allotransplantability in the TA3 tumor of the mouse: studies on segregating TA3-HA hybrids

In a series of six TA3-HA/A.CA hybrid cell lines formed by the fusion of the TA3-HA mammary carcinoma of a strain A mouse with a normal embryonic fibroblast of an A.CA mouse and then converted to the ascites form in parental strain A, the capacity to grow in foreign strains was inversely related to the ability to absorb anti-H-2a antibody. The absorptive capacities of the hybrid cell lines were intermediate between the low absorptive capacity of the non-strain-specific parent TA3-HA ascites cell line and the much higher absorptive capacity of the strain-specific ascites line TA3-St of the same tumor. Each hybrid cell line possessed an abundance of large endogenous cell-surface glycoprotein molecules similar to epiglycanin, a glycoprotein detected at the surface of the parent TA3-HA cell. The results suggested that the amount of epiglycanin-like material at the hybrid cell surfaces, determined by chemical and immunochemical methods, may have been directly related to the capacities of the cells to grow in foreign mouse strains and inversely related to their capacities to absorb anti-H-2a antibody.

Spin labeling of a cysteine residue of the Escherichia coli outer membrane lipoprotein in its membrane environment

A method was developed to attach a spin label to a specific site on the structural lipoprotein of the Escherichia coli outer membrane in situ. This method takes advantage of the fact that the outer membrane of wild-type E. coli contains few residues reactive towards sulfhydryl reagents. A mutant E. coli strain has been isolated [Suzuki, H., Nishimura, Y., Iketani, H., Campisi, J., Hirashima, A., Inouye, M. & Hirota, Y. (1976) J. Bacteriol. 127, 1494-1501] in which the second position from the carboxy terminus of the lipoprotein is changed from arginine into a cysteine residue. The membrane fraction of this mutant was treated with N-(1-oxyl-2,2,5,5-tetramethylpyrrolidinyl)maleimide in the presence of EDTA and 2-mercaptoethanol. Spin label was found to be preferentially incorporated into the lipoprotein. The spectrum of the spin-labeled membrane shows two components, both arising from spin label at the same site near the carboxy terminus. The strongly immobilized component has a maximum hyperfine splitting value of 53 G, and the weakly immobilized component, 37 G. A fraction of the lipoprotein is covalently bound to the peptidoglycan layer through its carboxy-terminal lysine; the spectrum of the isolated bound form of the lipoprotein was identical to that of the free form. When the matrix protein, the other major outer membrane protein, was removed by mutation, the spectrum of the lipoprotein was altered, suggesting that these two proteins are closely associated.

Amino acid replacement in a mutant lipoprotein of the Escherichia coli outer membrane

The primary structure of a mutant lipoprotein of the outer membrane of Escherichia coli was investigated. This mutant was previously described as a mutant that forms a dimer of the lipoprotein by an S-S bridge (H. Suzuki et al., J. Bacteriol. 127:1494-1501, 1976). The amino acid analysis of the mutant lipoprotein revealed that the mutant lipoprotein had an extra cysteine residue, with concomitant loss of an arginine residue. From the analysis of the mutant lipoprotein revealed that the mutant lipoprotein had an extra cysteine residue, with concomitant loss of an arginine residue. From the analysis of tryptic peptides, it was found that the arginine residue at position 57 was replaced with a cysteine residue. The amino terminal structure of the mutant lipoprotein was found to be glycerylcysteine, as in the case of the wild-type lipoprotein. The present results show that the mutation that was previously determined to map at 36.5 min on the E. coli chromosome occurred in the structure gene (lpp) for the lipoprotein. This was further confirmed by the fact that a merodiploid carrying both lpp+ and lpp produces not only the wild-type lipoprotein but also the mutant lipoprotein.

Optical properties of an outer membrane lipoprotein from Escherichia coli

The infrared spectrum of a structural lipoprotein from the Escherichia coli outer membrane indicated the lipoprotein had an alpha-helical conformation but no sign for the existence of beta-structures. From circular dichroism spectra of the lipoprotein, the alpha-helical content of the protein was found to be as high as 88% in 0.01-0.03% sodium dodecyl sulfate in the presence of 10(-5) M Mg2+ at pH 7.1 and 23 degrees C. When sodium dodecyl sulfate concentration increased higher than 0.1%, the alpha-helical content of the lipoprotein decreased to about 57%. Divalent cations, such as Mg2+ and Mn2+, were found to increase the helical content of the lipoprotein. The high alpha-helical content of the lipoprotein was observed in a wide range of temperatures (23 to 55 degrees C). The significance of the high alpha-helical content of the lipoprotein is discussed in light of the three-dimensional molecular models of the lipoprotein proposed previously.

Nucleotide sequence of the 5' end of araBAD operon messenger RNA in Escherichia coli B/r

The transcription reaction in vitro provides a means of analyzing the nucleotide sequence of the mRNA of the araBAD operon. By controlling the time of synthesis, we obtained araBAD mRNA of varying lengths beginning from the 5' end. These 5' fragments were freed of lambda RNA transcripts by successive hybridizations to the sense strands of a pair of lambda ara transducing phages that carry ara genes in opposite orientations. The purified 5' fragments were ordered by their times of appearance during synchronized RNA elongation and by nearest neighbor analyses. The results, when combined with the knowledge of the NH2-terminal sequence of the product of the first cistron (L-ribulokinase gene araB), establish the nucleotide sequence of the first 69 bases at the 5' end of the araBAD operon mRNA. The AUG starter codon for L-ribulokinase is located at positions 29-31. The sequence is: 5' A-C-C-C-G-U-U-U-U-U-U-U-U-G-G-A-U-G-G-A-G-U-G-A-A-A-C-G-A-U-G-G-C-G-A-U-U-G-C-A-A-U-U-G-G-C-C-U-C-G-A-U-U-U-U-G-C-A-G-U-G-A-U-U-C-U-G-(U)-. . .3'.

Serologically detectable specific and cross-reactive antigens on the membrane of a polyoma virus-induced murine tumor

With the aid of an assay measuring complement-dependent cytotoxocity mediated by syngeneic antibodies, we performed a serological analysis of surface antigens of a polyoma-virus-induced murine tumor (SEYF-a). In vivo propagated SEYF-a ascites tumor cells expressed a specific membrane antigen in addition to various other cross-reacting antigens. Among these we could identify at least four separate specificities. Two of these were present on MuLV-induced lymphoma cells, the first on Moloney-virus-induced YAC cells and the second on Gross-virus-induced GHA cells. The third cross-reacting antigen was detected on EL-4 cells. At least one additional specificity was present on two methylcholantthrene-induced murine sarcomas. Normal syngeneic lymphoid cells were insensitive to cytotoxicity mediated by the anti-tumor antisera. Quantitative and perhaps also qualitative differences between that antigenic expression of in vivo propagated on cultured SEYF-a cells were indicated. These studies show that hyperimmune sera produced in syngeneic mice against transplanted tumors may contain a considerable number of antibody specificities, only some of which are specific for the tumor. Furthermore, the results also suggest that polyoma-virus-induced tumors may possess individually distinct antigenic specificities, over and above the known cross-reacting TSTA or TSSA type antigen.

Lipoprotein from the outer membrane of Escherichia coli: purification, paracrystallization, and some properties of its free form

In the envelope of Escherichia coli, is a lipoprotein of molecular weight 7,200 as a major envelope protein. This lipoprotein was previously shown to exist in two different forms in the outer membrane of E. coli: the free form and the boundform, which is covalently linked to the peptidoglycau. The free form of the lipoprotein has been purified and paracrystallized by adding acetone to a sodium dodecyl sulfate solution in the presence of magnesium ion. The paracrystals were needle shaped. An electron micrograph of the negatively stained paracrystals showed a highly ordered ultrastructure. The chemical structure of the free form was compared with that of the bound form by (i) the amino acid composition, (ii) the fatty acid composition, and (iii) the peptide analysis after cyanogen bromide cleavage. The alpha-helical content of the free form of the lipoprotein was measured from the circular dichroism spectrum of the lipoprotein in 0.01% sodium dodecyl sulfate and found to be 87%. Using the purified lipoprotein as antigen, antiserum against the free form of the lipoprotein was obtained. Immunoprecipitation of the lipoprotein with the antiserum was found to be very specific, since only the free form of the lipoprotein was found as a major peak when the antiserum was reacted with the whole envelope proteins solubilized in 0.2% sodium dodecyl sulfate, and the immunoprecipitate thus formed was analyzed by polyacrylamide gel electrophoresis.

Isolation of specialized transducing bacteriophage lambda carrying genes of the L-arabinose operon of Escherichia coli B/r

A heat-inducible lysis-defective phage lambda (lambdacI857S7) has been integrated at multiple sites within the L-arabinose region (araCOIBAD) of a strain of Escherichia coli K-12 deleted for the normal lambda attachment site (lambdaattdelta). The lambda phage has become integrated with opposite orientations at two different loci within the aratb gene and with the "normal" orientation (clockwise N-RA-J) at a single site in the araC gene. The burst size, spontaneous-curing frequencies, and number of prophage harbored by each of the ara secondary-site lysogens have been determined. From these secondary-site lysogens it has been possible to generate plaque-forming ara-transducing phage (lambdapara) and defective ara-transducing phage (lambdadara), as well as defective leucine-transducing particles (lambdadleu). The construction and characterization of these lambdaara-transducing phage and their derivatives which carry genetically defined portions of the L-arabinose region are presented.