Nucleotide sequence of traQ and adjacent loci in the Escherichia coli K-12 F-plasmid transfer operon

The F tra operon region that includes genes trbA, traQ, and trbB was analyzed. Determination of the DNA sequence showed that on the tra operon strand, the trbA gene begins 19 nucleotides (nt) distal to traF and encodes a 115-amino-acid, Mr-12,946 protein. The traQ gene begins 399 nt distal to trbA and encodes a 94-amino-acid, Mr-10,867 protein. The trbB gene, which encodes a 179-amino-acid, Mr-19,507 protein, was found to overlap slightly with traQ; its start codon begins 11 nt before the traQ stop codon. Protein analysis and subcellular fractionation of the products expressed by these genes indicated that the trbB product was processed and that the mature form of this protein accumulated in the periplasm. In contrast, the protein products of trbA and traQ appeared to be unprocessed, membrane-associated proteins. The DNA sequence also revealed the presence of a previously unsuspected locus, artA, in the region between trbA and traQ. The artA open reading frame was found to lie on the DNA strand complementary to that of the F tra operon and could encode a 104-amino-acid, 12,132-dalton polypeptide. Since this sequence would not be expressed as part of the tra operon, the activity of a potential artA promoter region was assessed in a galK fusion vector system. In vivo utilization of the artA promoter and translational start sites was also examined by testing expression of an artA-beta-galactosidase fusion protein. These results indicated that the artA gene is expressed from its own promoter.

HLA and Chinese IgA nephropathy in Taiwan

No HLA-A, B, C, DR, DQ association was found in 80 Chinese IgA nephropathy patients. In addition, no prognostic genetic marker was discovered. The subgroup of those with gross hematuria was immunogenetically distinct from the subgroup of those without gross hematuria.

Fetal sex identification and prenatal bonding

This study explored the relation between expectant parents' knowledge of fetal sex and their attachment to their fetuses. During a routine 18-wk. prenatal visit, 126 expectant couples from an HMO population independently completed a background questionnaire and Fetal Attachment Scales of Cranky. During a routine 34-wk. obstetrical ultrasound examination those who chose to know were informed of the fetal sex. Total attachment scales were readministered during the 37th week. Parents' sex, knowledge of fetal sex, and the passage of time significantly affected attachment scores. Both parents' scores increased over time. Mothers' scores increased at a greater rate than the fathers'. Those parents who knew the fetal sex had significantly lower scores than those who did not. Whether the sex of the fetus was the preferred sex was nonsignificant. Results were derived from a double multivariate analysis of variance which controlled the within-couple and within-subject effects.

The product of the F plasmid transfer operon gene, traF, is a periplasmic protein

The products of clones carrying the F plasmid transfer operon gene, traF, were analyzed. Proteins expressed in maxicells were labeled with [35S]methionine and examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Clones carrying the wild-type traF gene expressed two polypeptide products that were not products of clones containing the traF13 amber mutation. These migrated with apparent molecular weights (Ma) of 27,000 and 25,000. A pulse-chase experiment suggested that the larger product was a precursor of the smaller one. In the presence of ethanol, the Ma-27,000 polypeptide accumulated and the Ma-25,000 product was not expressed. These results indicated that the traF protein undergoes proteolytic processing associated with export. Cell fractionation experiments further indicated that the greatest concentration of the mature (Ma 25,000) TraF protein was located in the periplasm. The DNA sequence of traF and the position of the transition mutation in traF13 DNA were also determined. Sequence analysis suggested that traF would be expressed as a 247-amino-acid, Mr-28,006 polypeptide. The 19 amino acids at the amino terminus of this polypeptide appear to constitute a typical membrane leader peptide, while the remainder of the molecule (Mr 25,942) is predicted to be primarily hydrophilic in character.

Metabolic changes in women using a long-acting monthly oral contraceptive and return of ovulation on discontinuation

Metabolic changes were investigated in two groups of women using oral contraceptives for 5 to 16 years. Blood samples were taken during the last cycle of oral contraceptive use and three months post-treatment. One group had used a monthly oral contraceptive (MOC, 3mg quinestrol and 10mg 16-methylene chlormadinone acetate) and the second group a daily oral contraceptive (DOC, 35 micrograms ethynylestradiol and 0.625 mg norethisterone). During treatment there were increases in serum total cholesterol and triglycerides but not HDL-C, in plasma total cortisol but not in renin activity, angiotensin II or urinary free cortisol excretion, in hemoglobin and some coagulation factors but not Factor X or antithrombin III, platelet function or fibrinolysis. The area under the blood glucose concentration-time curve, but not that for serum insulin, was slightly increased and there was no change in fasting blood sugar concentrations. All metabolic parameters, except plasma cortisol, which had shown an increase on treatment, had decreased to control levels within 3 months. Ovulation returned promptly in all women, the mean time being 70 days for Group MOC and 44 days for Group DOC. Thus, in spite of the long duration of use of the oral contraceptives, metabolic changes were minor.

Location of F plasmid transfer operon genes traC and traW and identification of the traW product

As part of an analysis of the conjugative transfer genes associated with the expression of F pili by plasmid F, we have investigated the physical location of the traC and traW genes. We found that plasmid clones carrying a 2.95-kilobase EcoRI-EcoRV F transfer operon fragment were able to complement transfer of F lac traC mutants and expressed an approximately 92,000-dalton product that comigrates with TraC. We also found that traW-complementing activity was expressed from plasmids carrying a 900-base-pair SmaI-HincII fragment. The traW product was identified as an approximately 23,000-dalton protein. The two different F DNA fragments that expressed traC and traW activities do not overlap. Our data indicate that the traC gene is located in a more-tra operon promoter-proximal position than suggested on earlier maps and that traW is distal to traC. These results resolve a long-standing question concerning the relationship of traW to traC. The clones we have constructed are expected to be useful in elucidating the role of proteins TraC and TraW in F-pilus assembly.

Analysis of transfer genes and gene products within the traB-traC region of the Escherichia coli fertility factor, F

A series of plasmids that carry overlapping segments of F DNA encoding the genes in the traB-traC interval was constructed, and a restriction enzyme map of the region was derived. Plasmids carrying deletions that had been introduced at an HpaI site within this interval were also isolated. The ability of these plasmids to complement transfer of F lac plasmids carrying mutations in traB, traV, and traW, and traC was analyzed. The protein products of the plasmids were labeled in UV-irradiated cells and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. These analyses showed that the product of traV is a polypeptide that migrates with an apparent molecular weight of 21,000. It was not detected when [35S]methionine was used to label plasmid products, but was readily detected in 14C-amino acid labeling experiments. A 21,500-dalton product appeared to stem from the region assigned to traP. A 9,000-dalton product was found to stem from a locus, named traR, that is located between traV and traC. No traW activity could be detected from the region of tra DNA examined. Our data also indicated that traC is located in a more promoter-proximal position than suggested on earlier maps. The plasmids constructed are expected to be useful in studies designed to identify the specific functions of the traB, -P, -V, -R, and -C products.

Analysis of Escherichia coli K12 F factor transfer genes: traQ, trbA, and trbB

The genes that encode the transfer properties of plasmid F, the fertility factor of Escherichia coli K12, are known to be clustered over a large, 33.3-kb segment of F DNA. As the central segment of the transfer region has not previously been well characterized, we constructed a detailed restriction map of the large F EcoRI DNA fragment, fl, and isolated a series of plasmid derivatives that carry various overlapping segments of this F tra operon DNA. We also analyzed the protein products of those clones that carried DNA segments extending over the region between traF and traH. This region was known to include traQ, a gene required for efficient conversion of the direct product of traA to the 7000-Da pilin polypeptide. We identified the traQ product as a polypeptide that migrates as a 12,500-Da protein on sodium dodecyl sulfate-polyacrylamide gels. We also detected the products of two other new genes that we have named trbA and trbB. These polypeptides migrate with apparent molecular weights of 14,200 and 18,400, respectively. Analysis of plasmid deletion derivatives that we constructed in vitro shows that these genes map in the order traF trbA traQ trbB traH. The presence of a plasmid carrying a small 0.43-kb fragment that expressed only the 12,500 traQ product caused the traA product of a co-resident compatible plasmid to be converted to the 7000-Da pilin polypeptide, demonstrating that TraQ is the only tra operon product required for this step of F-pilin biosynthesis.