The hierarchy of KorB binding at its 12 binding sites on the broad-host-range plasmid RK2 and modulation of this binding by IncC1 protein 1 1Edited by J. Karn

Kostelidou, Kalliopi; Thomas, Christopher M.

doi:10.1006/jmbi.1999.3359

Cited by 35 publications

(35 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2), even though they did not disrupt any genes. The low stability of these two plasmids might be due to the disturbance of the tight regulation of the plasmids (28,49,61). In fact, in pBPTn/J-3, Tn21Km was inserted in one of the binding sites for the regulation protein KorB (insertion site and consensus sequence, TTTA2GCGG CTAAA).…”

Section: Discussionmentioning

confidence: 99%

Region-Specific Insertion of Transposons in Combination with Selection for High Plasmid Transferability and Stability Accounts for the Structural Similarity of IncP-1 Plasmids

et al. 2007

View full text Add to dashboard Cite

The overall architecture of IncP-1 plasmids is very conserved in that the accessory genes are typically located in one or two specific regions: between oriV and trfA and between the tra and trb operons. Various hypotheses have been formulated to explain this, but none have been tested experimentally. We investigated whether this structural similarity is due to region-specific transposition alone or also is reliant on selection for plasmids with insertions limited to these two regions. We first examined the transposition of Tn21Km into IncP-1␤ plasmid pBP136 and found that most Tn21Km insertions (67%) were located around oriV. A similar experiment using the oriV region of IncP-1␤ plasmid pUO1 confirmed these results. We then tested the transferability, stability, and fitness cost of different pBP136 derivatives to determine if impairment of these key plasmid characters explained the conserved plasmid architecture. Most of the pBP136 derivatives with insertions in transfer genes were no longer transferable. The plasmids with insertions in the oriV-trfA and tra-trb regions were more stable than other plasmid variants, and one of these also showed a significantly lower fitness cost. In addition, our detailed sequence analysis of IncP-1 plasmids showed that Tn402/5053-like transposons are situated predominantly between the tra and trb operons and close to the putative resolution site for the ParA resolvase, a potential hot spot for those transposons. Our study presents the first empirical evidence that region-specific insertion of transposons in combination with selection for transferable and stable plasmids explains the structural similarity of IncP-1 plasmids.

show abstract

Section: Discussionmentioning

confidence: 99%

Region-Specific Insertion of Transposons in Combination with Selection for High Plasmid Transferability and Stability Accounts for the Structural Similarity of IncP-1 Plasmids

et al. 2007

View full text Add to dashboard Cite

show abstract

“…ParB binds to a specific centromerelike sequence (parS) on the chromosome forming a higher order nucleoprotein complex that is thought to pair the sister chromosomes/plasmids. ParA, an ATPase, binds to ParB and is thought to act as a motor, pulling or pushing two ParB-bound chromosomes apart to different poles of the bacterial cell (2)(3)(4).…”

mentioning

confidence: 99%

“…KorB binds simultaneously with RNA polymerase at promoters and interacts with it to prevent open complex formation (17). KorB can act upstream or downstream of the promoters and also at a distance (2)(3)(4)9). At all promoters, KorB acts cooperatively with a second repressor, either KorA, TrbA, or KorC, forming a regulatory network that coordinates expression of the operons on the plasmid (3,6,7,16).…”

mentioning

confidence: 99%

Order and Disorder in the Domain Organization of the Plasmid Partition Protein KorB

Rajasekar

Muntaha

Tame

et al. 2010

Journal of Biological Chemistry

View full text Add to dashboard Cite

The plasmid partition protein KorB has a dual role: it is essential for the correct segregation of the low copy number broad host range RK2 plasmid while also being an important regulator of transcription. KorB belongs to the ParB family of proteins, and partitioning in RK2 has been studied as a simplified model of bacterial chromosome segregation. Structural information on full-length ParB proteins is limited, mainly due to the inability to grow crystals suitable for diffraction studies. We show, using CD and NMR, that KorB has regions of significant intrinsic disorder and hence it adopts a multiplicity of conformations in solution. The biophysical data are consistent with bioinformatic predictions based on the amino acid sequence that the N-terminal region and also the region between the central DNA-binding domain and the C-terminal dimerization domain are intrinsically disordered. We have used small angle x-ray scattering data to determine the ensemble of solution conformations for KorB and selected deletion mutants, based on models of the known domain structures. This conformational range of KorB is likely to be biologically required for DNA partitioning and for binding to a diverse set of partner proteins.

show abstract

“…KorB binds specifically to twelve places on the plasmid genome (KorB operators O B 1 to O B 12) (1,24), with a hierarchy of binding affinities (10). Five of these sites (O B 4, O B 5, O B 7, O B 8, and O B 9) are within the regions encoding transfer genes, but none of them are very close to promoters, and only one of them (O B 9) is known to mediate KorB repression of transcription.…”

mentioning

confidence: 99%

Cooperativity between KorB and TrbA Repressors of Broad-Host-Range Plasmid RK2

et al. 2001

View full text Add to dashboard Cite

The KorB and TrbA proteins of broad-host-range plasmid RK2 are key regulators of the plasmid genes required for conjugative transfer. trbBp is the primary promoter responsible for expression of mating pair formation genes. We show that despite the targets for KorB and TrbA at trbBp being about 165 bp apart, 189 bp upstream of the transcription start point and overlapping the ؊10 region, respectively, these two proteins show up to 10-fold cooperativity for the repression of trbBp. Deletion analysis of TrbA showed that the Cterminal domain (CTD), which has a high degree of sequence conservation with the CTD of KorA, is required for this cooperativity with KorB. Western blotting demonstrated that the apparently mutual enhancement of repression is not due simply to elevation of repressor level by the presence of the second protein, suggesting that the basis for cooperativity is interaction between KorB and TrbA bound at their respective operators.The self-transmissible, broad-host-range plasmid RK2 (indistinguishable from RP4 and RP1) has been studied in great detail (17). Its replication, partitioning, and transfer functions show many features of interest, but its most striking aspect is the complex regulatory circuitry which coordinates expression of the genes for all these basic functions. The regulatory proteins responsible for this coordination are KorA and KorB, encoded in the central control operon; KorC, encoded in the klc operon; and TrbA, encoded before the trb operon. The study described in this paper focused on the interactions between KorB and TrbA at trbBp (Fig.

show abstract

The hierarchy of KorB binding at its 12 binding sites on the broad-host-range plasmid RK2 and modulation of this binding by IncC1 protein 1 1Edited by J. Karn

Cited by 35 publications

References 34 publications

Region-Specific Insertion of Transposons in Combination with Selection for High Plasmid Transferability and Stability Accounts for the Structural Similarity of IncP-1 Plasmids

Region-Specific Insertion of Transposons in Combination with Selection for High Plasmid Transferability and Stability Accounts for the Structural Similarity of IncP-1 Plasmids

Order and Disorder in the Domain Organization of the Plasmid Partition Protein KorB

Cooperativity between KorB and TrbA Repressors of Broad-Host-Range Plasmid RK2

Contact Info

Product

Resources

About