Topic
Multicistronic message
About: Multicistronic message is a research topic. Over the lifetime, 34 publications have been published within this topic receiving 1475 citations.
Papers
TL;DR: Nine additional adjacent genes involved in type III capsule production are cloned and sequenced, suggesting that a single gene can confer serotype specificity in organisms that produce complex polysaccharides.
Abstract: Streptococcus agalactiae is a primary cause of neonatal morbidity and mortality. Essential to the virulence of this pathogen is the production of a type-specific capsular polysaccharide (CPS) that enables the bacteria to evade host immune defenses. The identification, cloning, sequencing, and functional characterization of seven genes involved in type III capsule production have been previously reported. Here, we describe the cloning and sequencing of nine additional adjacent genes, cpsIIIFGHIJKL, neuIIIB, and neuIIIC. Sequence comparisons suggested that these genes are involved in sialic acid synthesis, pentasaccharide repeating unit formation, and oligosaccharide transport and polymerization. The type III CPS (cpsIII) locus was comprised of 16 genes within 15.5 kb of contiguous chromosomal DNA. Primer extension analysis and investigation of mRNA from mutants with polar insertions in their cpsIII loci supported the hypothesis that the operon is transcribed as a single polycistronic message. The translated cpsIII sequences were compared to those of the S. agalactiae cpsIa locus, and the primary difference between the operons was found to reside in cpsIIIH, the putative CPS polymerase gene. Expression of cpsIIIH in a type Ia strain resulted in suppression of CPS Ia synthesis and in production of a CPS which reacted with type III-specific polyclonal antibody. Likewise, expression of the putative type Ia polymerase gene in a type III strain reduced synthesis of type III CPS with production of a type Ia immunoreactive capsule. Based on the similar structures of the oligosaccharide repeating units of the type Ia and III capsules, our observations demonstrated that cpsIaH and cpsIIIH encoded the type Ia and III CPS polymerases, respectively. Additionally, these findings suggested that a single gene can confer serotype specificity in organisms that produce complex polysaccharides.
128 citations
TL;DR: This study has revealed that the 4881 nt of the P1 structural gene are flanked by ORFs, and there are no obvious ribosome-binding sites or transcription termination sequences in the immediately adjacent regions, which suggests that the P 1 gene is transcribed as part of a larger polycistronic message.
116 citations
TL;DR: The Epstein-Barr virus nuclear antigen (EBNA I) present in latently infected cells is encoded in a 2-kilobase exon contained in the BamHI K viral genomic fragment, but this exon is, however, found within a 3.7- kilobase mRNA transcript.
Abstract: The Epstein-Barr virus nuclear antigen (EBNA I) present in latently infected cells is encoded in a 2-kilobase exon contained in the BamHI K viral genomic fragment. This exon is, however, found within a 3.7-kilobase mRNA transcript. The origin of the remaining 1.7 kilobases is unknown, although it is not derived from adjacent Epstein-Barr virus DNA sequences. A 1.1-kilobase cDNA clone generated by primer extension using an oligonucleotide complimentary to a sequence 245 base pairs 3' to the putative initiation codon for EBNA I in the BamHI K fragment has been isolated. This clone contains seven exons (from the BamHI W, Y, U, E, and K viral genomic fragments), which are spread over approximately 70 kilobases of the viral genome. However, this clone does not appear to contain the complete 5' end of the transcript. In addition to the open reading frame in the exon encoding EBNA I, three other open reading frames are found in this transcript that potentially encode other viral antigens present in latently infected cells.
110 citations
TL;DR: Northern (RNA) blot and primer extension analyses of total cellular RNA indicate that all four genes are transcribed, and the N termini of all four flagellins are very hydrophobic, and this region shows a high degree of homology with the flageLLins from Halobacterium halobium.
Abstract: The flagellins of Methanococcus voltae are encoded by a multigene family of four related genes (flaA, flaB1, flaB2, and flaB3). All four genes map within the same region of the genome, with the last three arranged in a direct tandem. Northern (RNA) blot and primer extension analyses of total cellular RNA indicate that all four genes are transcribed. The flaB1, flaB2, and flaB3 flagellins are transcribed as part of a large polycistronic message which encodes at least one more protein which is not a flagellin. An intercistronic stem-loop followed by a poly(T) tract located between the flaB2 and flaB3 genes appears to increase the resistance of the flaB1/flaB2 portion of this polycistronic message to digestion by endogenous RNases. The flaA gene, located approximately 600 bp upstream from the tandem, is transcribed as a separate message at very low levels. The four open reading frames encode proteins of molecular weights 23,900, 22,400, 22,800, and 25,500, much less than the Mr values of 33,000 and 31,000 for the flagellins calculated from sodium dodecyl sulfate-polyacrylamide gel electrophoresis of isolated flagellar filaments. Each flagellin contains multiple eukaryotic glycosylation signals (Arg-X-Ser/Thr), although they do not appear to be glycoproteins, and each has an 11- or 12-amino-acid leader peptide. The N termini of all four flagellins (amino acids 1 through 47 of the mature protein) are very hydrophobic, and this region shows a high degree of homology with the flagellins from Halobacterium halobium. Images
96 citations
TL;DR: This study indicates that the P1 gene is transcribed as part of a larger polycistronic message in virulent Mycoplasma pneumoniae.
89 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2012 | 2 |
| 2010 | 1 |
| 2007 | 1 |
| 2004 | 1 |
| 2003 | 1 |
| 2002 | 3 |