Experimental genome evolution: large-scale genome rearrangements associated with resistance to replacement of a chromosomal restriction-modification gene complex

Citation
N. Handa et al., Experimental genome evolution: large-scale genome rearrangements associated with resistance to replacement of a chromosomal restriction-modification gene complex, MOL MICROB, 40(4), 2001, pp. 932-940
Citations number
36
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
MOLECULAR MICROBIOLOGY
ISSN journal
0950-382X → ACNP
Volume
40
Issue
4
Year of publication
2001
Pages
932 - 940
Database
ISI
SICI code
0950-382X(200105)40:4<932:EGELGR>2.0.ZU;2-I
Abstract
Type II restriction enzymes are paired with modification enzymes that prote ct type II restriction sites from cleavage by methylating them. A plasmid c arrying a type II restriction-modification gene complex is not easily repla ced by an incompatible plasmid because loss of the former leads to cell dea th through chromosome cleavage. In the present work, we looked to see wheth er a chromosomally located restriction-modification gene complex could be r eplaced by a homologous stretch of DNA, We tried to replace the PaeR71 gene complex on the Escherichia coli chromosome by transducing a homologous str etch of PaeR71-modified DNA, The replacement efficiency of the restriction- modification complex was lower than expected. Some of the resulting recombi nant clones retained the recipient restriction-modification gene complex as well as the homologous DNA (donor allele), and slowly lost the donor allel e in the absence of selection. Analysis of their genome-wide rearrangements by Southern hybridization, inverse polymerase chain reaction (iPCR) and se quence determination demonstrated the occurrence of unequal homologous reco mbination between copies of the transposon IS3, It was strongly suggested t hat multiple rounds of unequal IS3-IS3 recombination caused large-scale dup lication and inversion of the chromosome, and that only one of the duplicat ed copies of the recipient PaeR71 was replaced.