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Biomedical subjects

V Scarlato

Publications and source records attributed to V Scarlato.

45 records · Page 3Linked to original sources
PubMed1990

Positive transcriptional feedback at the bvg locus controls expression of virulence factors in Bordetella pertussis.

Regulation of the genes coding for virulence factors in Bordetella pertussis is controlled by the bvg locus, which encodes one putative sensory protein (BvgS) and one positive regulator of transcription (BvgA). We have studied the transcription of the bvg locus and found that this is controlled by a 350-base-pair DNA fragment, which contains five promoters, three of which transcribe the bvg locus, one transcribes an antisense RNA, and one transcribes a virulence-associated gene. Under noninducing conditions, only the promoter P2 is active and this is responsible for the production of low amounts of regulatory proteins. Upon induction, the other four promoters become active and, by a mechanism that may involve transcriptional and translational regulation, cause a 50-fold increase of the transcriptional activator BvgA. A model of the autoregulation of the bvg locus is presented.

Bacterial Proteins↗
PubMed1990

Genetic characterization of Bordetella pertussis filamentous haemagglutinin: a protein processed from an unusually large precursor.

The nucleotide sequence of the structural gene for filamentous haemagglutinin (FHA), fhaB, a crucial adherence factor for Bordetella pertussis, has been determined. Its 10774 nucleotides are far more than necessary to encode the 220 kD biologically active, mature polypeptide product, suggesting a role for co- or post-translational processing. Fusion proteins derived from various portions of the fhaB open reading frame (ORF) were used to generate polyclonal antisera. Western immunoblot analysis of purified FHA and Bordetella sp. whole cell extracts with these antisera indicated that the 220 kD product is encoded by the 5' portion of the ORF and that the smaller polypeptide species are breakdown products of this polypeptide. These data, as well as N-terminal amino acid sequencing of the major polypeptide species, suggest a scheme for the proteolytic processing of an FHA precursor polypeptide.

Adhesins, Bacterial↗
PubMed1989

Characterization of the structural genes for the DNA-binding protein H-NS in Enterobacteriaceae.

The promoter region of Escherichia coli hns, the structural gene for the DNA-binding protein H-NS, has been identified by use of a promoter search vector and the in vivo transcriptional start point by primer extension analysis. The homologous hns genes of two other Enterobacteriaceae, Proteus vulgaris and Serratia marcescens, were identified by heterologous hybridization with a DNA probe derived from E. coli hns, cloned and sequenced. Taking into account only the invariant nucleotides and amino acids, the homology of H-NS among the three organisms was found to be greater than 70% at the DNA level and greater than 75% at the protein level. The three hns genes were also found to have nearly identical transcriptional and translational signals.

Amino Acid Sequence↗
PubMed1989

Bacteriophage T4 late gene expression: overlapping promoters direct divergent transcription of the base plate gene cluster.

Eight 5' ends of RNA molecules which encompass the bacteriophage T4 base plate late genes 51 to 26 region have been mapped by S1 nuclease protection and reverse transcription within a 246-bp DNA segment. Two of eight 5' ends are initiated at two absolutely conserved late promoter sites, P51 and P26a, that direct RNA synthesis on opposite strands. These two promoters share four of eight promoter sequence base pairs. A third 5' end arises from another promoter, P26b, which shows one base pair mismatch with respect to the absolutely conserved -10 sequence. All the other 5' ends arise from RNA processing and/or degradation. Since no other late transcription promoter sites were found within the base plate cluster sequence, we propose that the two overlapping late promoters, P51 and P26a, direct the expression of the T4 base plate gene cluster, included between map coordinates 114,000 and 121,038: P51 directs the transcription of genes 51, 27, 28, 29, 48, and 54 on the rDNA strand and P26a the transcription of genes 26 and 25 on the /DNA strand. This peculiar promoter configuration might account for the low level of transcription of these late genes.

Amino Acid Sequence↗
PubMed1988

Symmetric transcription of bacteriophage T4 base plate genes.

Dot-blot and Northern-blot experiments, using strand-specific RNA probes, show that part of the bacteriophage T4 DNA that codes for six of the base plate structural genes (gp 51, 27, 28, 29, 48 and 54), is transcribed in vivo from both DNA strands. The r DNA strand transcripts contain sequences which are translated into structural proteins. Antisense l strand RNA is about 100 fold less abundant than RNA molecules transcribed from the r DNA strand.

Blotting, Northern↗
PubMed1984

Statistical evaluation of the coding capacity of complementary DNA strands.

Two independent methods are used to evaluate the protein-coding information content in different classes of DNA sequences. The first method allows to evaluate the statistical relevance of finding unidentified reading frames, longer than 100 codons, on both DNA strands of: a) 117 DNA sequences that code for 142 nuclear proteins; b) 39 stable RNA coding sequences and c) 36 other DNA sequences which include regulatory and as yet unknown function sequences. The finding of 50 reading frames longer than 100 codons (complementary inverted proteins or c.i.p. genes) located on the DNA strand complementary to the protein-coding one is drastically in excess of the number predicted by chance alone. An independent method (testcode) applied to c.i.p. gene sequences, which assigns the probability of coding to a given sequence, predicts that more than 50% of these genes are translated in a functional product. These analyses indicate the existence of a new class of protein-coding genes, located on the DNA sequences complementary to the protein-coding DNA strand.

Animals↗
PubMed1981

Coding capacity of complementary DNA strands.

A Fortran computer algorithm has been used to analyze the nucleotide sequence of several structural genes. The analysis performed on both coding and complementary DNA strands shows that whereas open reading frames shorter than 100 codons are randomly distributed on both DNA strands, open reading frames longer than 100 codons ("virtual genes") are significantly more frequent on the complementary DNA strand than on the coding one. These "virtual genes" were further investigated by looking at intron sequences, splicing points, signal sequences and by analyzing gene mutations. On the basis of this analysis coding and complementary DNA strands of several eukaryotic structural genes cannot be distinguished. In particular we suggest that the complementary DNA strand of the human epsilon-globin gene might indeed code for a protein.

Animals↗