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Category: Microbial Genetics and Molecular Biology
Virulence Plasmids of Yersinia: Characteristics and Comparison, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555817732/9781555812652_Chap20-1.gif /docserver/preview/fulltext/10.1128/9781555817732/9781555812652_Chap20-2.gifAbstract:
This chapter focuses on virulence plasmids of Yersinia species with particular emphasis on their architecture, the virulence factors encoded by them, and comparisons between species and strains where possible. The involvement of plasmids in the virulence of Yersinia has long been known and is well established. The best-characterized of these is the low calcium response (LCR) plasmid that is common to the three pathogenic Yersinia species. The synthesis and regulation of effector Yop secretion by the type III system are extremely complex. The largest difference between the pLcr molecules that have been sequenced to date is in the position and orientation of some of the more important genes. The common mechanism of partitioning between the sequenced pLcr plasmids is interesting because the common partitioning system has been shown to be responsible for plasmid incompatibility between F and pYVe. The chapter addresses the putative virulence factors encoded by pFra as well as make postgenomic sequence comparisons where possible. The most prominent phage element that can be identified easily as a remnant on pFra is a portion of a lambda-like phage element. Recently, two independent self-transmissible antibiotic resistance plasmids (RTFs) have been identified in natural isolates of Y. pestis in Madagascar.
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Map of the common 26-kb core region encoding the type III secretion system of the Yersinia virulence plasmid. Genes and direction of transcription are indicated by arrows. Genes and alternate names used in the different Yersinia species are labeled with each coding region. The IcrA, IcrB, and IcrC designations were originally used for three separate loci identified by study oflacZ fusions in Y. pestis ( 33 ). The vir designation is used in Y. enterocolitica ( 40 ). The Icr loci divide the majority of the core region (excluding IcrG-yopD) into three parts. The IcrA locus extends from IcrE (yopN) to IcrR. The IcrB region extends from yscN to yscV. The IcrC locus includes the yscA through IcrQ (yscMt in Y. enterocolitica).
Map of the common 26-kb core region encoding the type III secretion system of the Yersinia virulence plasmid. Genes and direction of transcription are indicated by arrows. Genes and alternate names used in the different Yersinia species are labeled with each coding region. The IcrA, IcrB, and IcrC designations were originally used for three separate loci identified by study oflacZ fusions in Y. pestis ( 33 ). The vir designation is used in Y. enterocolitica ( 40 ). The Icr loci divide the majority of the core region (excluding IcrG-yopD) into three parts. The IcrA locus extends from IcrE (yopN) to IcrR. The IcrB region extends from yscN to yscV. The IcrC locus includes the yscA through IcrQ (yscMt in Y. enterocolitica).
Comparative gene maps of the three sequenced pLcr plasmids. The sequences have been oriented such that the replication region is at the top of the map and the LCR core gene cluster is placed first proceeding clockwise around the circle. Only genes of interest are shown, with arrows indicating the direction of transcription. The closed dots indicate the position of the sequence GTATT. The locations of IS elements or remnants (designated with a “-r"” suffix) arc also shown and discussed in the text. Regions I, II, and III shown on the pCDl map are discussed in the text.
Comparative gene maps of the three sequenced pLcr plasmids. The sequences have been oriented such that the replication region is at the top of the map and the LCR core gene cluster is placed first proceeding clockwise around the circle. Only genes of interest are shown, with arrows indicating the direction of transcription. The closed dots indicate the position of the sequence GTATT. The locations of IS elements or remnants (designated with a “-r"” suffix) arc also shown and discussed in the text. Regions I, II, and III shown on the pCDl map are discussed in the text.
Gene map of the replication region of pCD1/pYVe227 and pYVc8081. The nomenclature of the genes is in keeping with the reports describing these plasmids ( 47 , 58 ). Although the locations of these genes are quite similar, the level of homology at the DNA and protein level is quite low (see text). Arrows indicate the direction of transcription. The numbers indicate base-pair positions in the DNA sequence for pCDl (GenBank accession no. AF074612) and pYVe8081 (GenBank accession no. AF336309). The oriR region includes the putative DnaA box and short repeat sequences generally found in plasmid origins.
Gene map of the replication region of pCD1/pYVe227 and pYVc8081. The nomenclature of the genes is in keeping with the reports describing these plasmids ( 47 , 58 ). Although the locations of these genes are quite similar, the level of homology at the DNA and protein level is quite low (see text). Arrows indicate the direction of transcription. The numbers indicate base-pair positions in the DNA sequence for pCDl (GenBank accession no. AF074612) and pYVe8081 (GenBank accession no. AF336309). The oriR region includes the putative DnaA box and short repeat sequences generally found in plasmid origins.
Comparative architecture of the murine toxin plasmid pMTl/pFra derived from GenBank sequence AF074611 ( 47 ). The black regions represent sequences in common with the cryptic S. enterica serovar Typhi plasmid pHCM2 ( 62 ). The light gray region represents DNA sequences that are absent in the Y. pestis CO92 plasmid pFra (GenBank accession no. AL117211). Genes and additional regions of interest are shown inside the circular map. The position of ORF123 is specifically shown because it shares 9 1% amino acid identity with ORFL7074 found on E. coli p0157 ( 47 ). Only intact IS elements are shown. Restriction sites for EcoRland HindIII are also shown.
Comparative architecture of the murine toxin plasmid pMTl/pFra derived from GenBank sequence AF074611 ( 47 ). The black regions represent sequences in common with the cryptic S. enterica serovar Typhi plasmid pHCM2 ( 62 ). The light gray region represents DNA sequences that are absent in the Y. pestis CO92 plasmid pFra (GenBank accession no. AL117211). Genes and additional regions of interest are shown inside the circular map. The position of ORF123 is specifically shown because it shares 9 1% amino acid identity with ORFL7074 found on E. coli p0157 ( 47 ). Only intact IS elements are shown. Restriction sites for EcoRland HindIII are also shown.
Molecular properties of Yersinia plasmids
Molecular properties of Yersinia plasmids
List of pLcr-encodcd established effector proteins and virulence properties
List of pLcr-encodcd established effector proteins and virulence properties