PMID:1931824
| Citation |
Blakely, G, Colloms, S, May, G, Burke, M and Sherratt, D (1991) Escherichia coli XerC recombinase is required for chromosomal segregation at cell division.New Biol. 3:789-98 |
|---|---|
| Abstract |
XerC is a site-specific recombinase of the bacteriophage lambda integrase family that is encoded by xerC at 3700 kbp on the genetic map of Escherichia coli. The protein was originally identified through its role in converting multimers of plasmid ColE1 to monomers; only monomers are stably inherited. Here we demonstrate that XerC also has a role in the segregation of replicated chromosomes at cell division. xerC mutants form filaments with aberrant nucleotides that appear unable to partition correctly. A DNA segment (dif) from the replication terminus region of the E. coli chromosome binds XerC and acts as a substrate for XerC-mediated site-specific recombination when inserted into multicopy plasmids. This dif segment contains a region of 28 bp with sequence similarity to the crossover region of ColE1 cer. The cell division phenotype of xerC mutants is suppressed in strains deficient in homologous recombination, suggesting that the role of XerC/dif in chromosomal metabolism is to convert any chromosomal multimers (arising through homologous recombination) to monomers. |
| Links | |
| Keywords |
Site-specific Recombination; Chromosome Dimers; Resolution; Binding Sites; Cell Division; Escherichia coli; Integrases; dif; cer |
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Main Points of the Paper
- xerC insertion mutants have defects in cell division and chromosomal nucleoid segregation
- mutations in recA suppress the xerC- phenotype
- site-specific recombination locus dif is related to cer (alignments included)
- dif is a substrate for XerC-mediated site-specific recombination
- XerC recombination at dif doesn't require ArgR or PepA
Materials and Methods Used
- xerC+ plasmid complementation of the xerC mutant phenotype
Phenotype Annotations
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| Species | Taxon ID | Strain | Gene (if known) | OMP | Phenotype | Details | Evidence | Notes |
|---|---|---|---|---|---|---|---|---|
|
xerC |
small colonies |
Growth |
on broth-containing plates |
Plating Assay |
xerCY17 and xerC2 are both insertion mutations | |||
|
xerC |
slow recovery from stationary phase |
Growth |
Growth Curve |
xerCY17 and xerC2 are both insertion mutations | ||||
|
xerC |
varying exponential growth rate |
Growth |
day-to-day variation of 80-100% compared to isogenic xerC+ strain |
Growth Curve |
xerCY17 and xerC2 are both insertion mutations | |||
|
xerC |
filamented cells |
Morphology |
variable number of filaments |
Microscopy |
xerCY17 and xerC2 are both insertion mutations | |||
|
xerC |
nonfilamentous cells at the two-cell stage |
Morphology |
excess number of these within the population |
Microscopy |
xerCY17 and xerC2 are both insertion mutations | |||
|
xerC |
mispositioned nucleoid |
Morphology |
single, highly amplified nucleoid at the filament midpoint and sometimes other places within the cell |
Microscopy |
Fiigure 1-B2: xerCY17 and xerC2 are both insertion mutations | |||
|
xerC |
abolished DNA dimer resolution |
Growth |
using a plasmid with dif site as a reporter for chromosome dimer resolution |
Biochemical Assay |
Figure 3- xerCY17 and xerC2 are both insertion mutations | |||
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Notes
References
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