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S A McIntire

Publications and source records attributed to S A McIntire.

10 recordsLinked to original sources
PubMed1995

Characterization of a 3.5-kbp plasmid from Helicobacter pylori.

A 3.5-kbp plasmid (pHPM180) was isolated from Helicobacter pylori (HPM180) and the DNA sequence was determined. Two open reading frames (ORF1 and ORF2) were identified which could encode polypeptides of 54,517 and 27,629 Da, respectively. Ribosome binding and promoter consensus sequences were identified, as well as two 232-bp direct repeats and four 22-bp direct repeats. DNA sequence homology was found between pHPM180 ORF1 and a 684-base pair HindIII fragment from a 5.6-kbp H. pylori plasmid. ORF1 showed amino acid homology with six replication proteins from bacterial plasmids with theta-type replicons. Additional sequence identity was found between pHPM180 noncoding DNA and a segment of H. pylori pHPK255, a plasmid that replicates via a rolling circle type mechanism. A ribonuclease protection assay determined that ORF1 was transcribed in H. pylori HPM180.

Amino Acid Sequence↗
PubMed1987

Fertility inhibition gene of plasmid R100.

The fin0 gene of R100 was isolated from the Fin0+ transducing phage VA lambda 57. The limits of the gene were determined by BAL31 digestions and by analysis of deletion mutations derived from an internal restriction site. The DNA sequence contained an open reading frame of 558 nucleotides that would encode a protein of 21,268 daltons. Synthesis of such a protein was observed only when the fragment was cloned in front of the TAC promoter. Deletions entering the large open reading frame from either end were Fin0-, while internal frame shift mutations retained high Fin0 activity. One such strain had a 13 bp internal deletion that would produce a protein of 63 amino acid residues of which 21 were basic. We were consequently unable to rigorously establish that the 558 base orf encoded a fin0 product. The strand opposite the large open reading frame contained several transcription termination signals, and it is possible that the active gene product is one or two small RNAs from this strand.

Bacteriophage lambda↗
PubMed1987

oriT sequence of the antibiotic resistance plasmid R100.

We present the nucleotide sequence of the oriT region from plasmid R100. Comparison to other IncF plasmids revealed homology around the proposed nick sites as well as conservation of inverted repeated sequences in the nonhomologous region. Three areas showed strong homology (eight of nine nucleotides) to the consensus sequence for binding of integration host factor, suggesting a role for this DNA-binding protein in nicking at oriT.

Anti-Bacterial Agents↗
PubMed1983

The finO gene of antibiotic resistance plasmid R100.

Lambda phages carrying the R100 finO gene have been isolated from an R100:: lambda cointegrate in which lambda was inserted into the R100 traD gene at kb coordinate 72.1. Physical analyses of these phages place the finO gene within R100 SalI fragment D, near kb coordinate 82.0. Analysis of proteins synthesized by the phages did not identify the finO gene product, although a constitutive protein of m.w. 30,100 was encoded by R100 DNA between kb coordinates 78.7 and 81.2.

Bacterial Proteins↗
PubMed1979

Lambda transducing phages derived from a FinO- R100::lambda cointegrate plasmid: proteins encoded by the R100 replication/incompatibility region and the antibiotic resistance determinant.

Three lambda transducing phages have been isolated from pEDR20, an R100::lambda cointegrate plasmid in which the lambda insertion inactivated the R100 finO gene. Physical analysis of the three phages showed that the lambda is inserted at kilobase coordinate 81.3 of R100. All three phages carry different amounts of R100 DNA in the left arm of lambda. Each pahge contains ISlb, the mer genes and the region between coordinate 81.3 and 88.6; thus, all contain the genes necessary for R100 replication. One phage, VA lambda 73, contains the entire r-determination of R100 in addition to the above DNA. Five proteins coded by the region between 81.3 and 88.6 were detected. These had subunit molecular weights of 10,400; 12,200; 16,200; 19,600; and 38,300. The first was made constitutively and the other four only from a lambda promoter. Other constitutive proteins were one from the cml fus region with a molecular weight of 22,400 (cml) and two from the str sul region with molecular weights of 31,500 (str?) and 30,100 (sul?). Mercuric ion induced synthesis of at least 10 proteins. Six of these were known from earlier work. The total size of the proteins which appear to derive from the mer genes exceeds by a factor of 1.5, the coding capacity of this region without overlapping genes. Some, or all of these extra proteins may be chromosomal in origin, possibly derepressed in response to mercury gene products.

Bacteriophage lambda↗
PubMed1978

Properties of lambda transducing bacteriophages carrying R100 plasmid DNA: mercury resistance genes.

Three lambdamer (resistance to Hg2+ and mercurials) transducing phages were prepared from three independent cointegrate isolates of bacteriophage lambda and plasmid R100. DNA heteroduplex and restriction nuclease analyses of the lambdamer DNA showed that all three phages had resulted from lambda insertion at kilobase coordinate 8.6 of plasmid R100, followed by loss of different lengths of lambda DNA and replacement with different lengths of R100 DNA. Two of the lambdamer phages were defective, containing deletions from lambdaatt through the lambdaN gene and into the lambdarex gene; the third, VAlambda14, was an N+ Spi- plaque-forming phage. With VAlambda14, N-dependent transcription of R100 mer from the lambdapL promoter suggested that transcription of mer proceeded in the direction from IS1b toward the sulfonamide resistance determinant (i.e., from a plasmid promoter in restriction nuclease fragment EcoRI-H toward fragment EcoRI-I). Phage-directed protein synthesis in a UV-irradiated lambdaind- lysogen showed the Hg2+-inducible synthesis of three major polypeptides of molecular weights 68,000, 11,500, and 8,500 and three minor ones of molecular weights 54,000, 33,000, and 13,500. The largest of the major polypeptides is identified as the subunit of the mercuric reductase enzyme. The functions of the smaller polypeptides are not known. Hg2+ reductase enzyme assays confirmed the regulation of mer synthesis during phage infection.

Bacterial Proteins↗
PubMedDate not supplied

Frequency in the United States of non-beta-lactamase-producing strains of Neisseria gonorrhoeae possessing the 24.5-Mdal conjugative plasmid.

We characterized 475 non-beta-lactamase-producing gonococcal isolates from five U.S. cities by auxotype, serovar, and plasmid content to determine the frequency of isolates with the 24.5-Mdal gonococcal conjugative plasmid. A total of 150 (32%) of all isolates possessed the 24.5-Mdal plasmid; these isolates represented between 10% and 53% of isolates from each city. Isolates possessing the 24.5-Mdal plasmid belonged to 45 (56%) of 81 auxotype/serovar (A/S) classes, or between 24% and 70% of the A/S classes isolated in each city. Overall, a higher proportion of strains isolated in the southern cities possessed the 24.5-Mdal plasmid than did those from northeastern or northwestern cities. These strains appear to have spread independently of the spread of beta-lactamase-producing Neisseria gonorrhoeae strains. The prevalence of N. gonorrhoeae strains with the 24.5-Mdal conjugative plasmid has increased substantially and may have important implications for the epidemiology of gonorrhea caused by beta-lactamase-producing strains.

Conjugation, Genetic↗