ACQUISITION OF RESISTANCE GENES BY THE INCQ PLASMID R1162 IS LIMITED BY ITS HIGH COPY NUMBER AND LACK OF A PARTITIONING MECHANISM

Citation
Ec. Becker et Rj. Meyer, ACQUISITION OF RESISTANCE GENES BY THE INCQ PLASMID R1162 IS LIMITED BY ITS HIGH COPY NUMBER AND LACK OF A PARTITIONING MECHANISM, Journal of bacteriology, 179(18), 1997, pp. 5947-5950
Citations number
17
Categorie Soggetti
Microbiology
Journal title
ISSN journal
00219193
Volume
179
Issue
18
Year of publication
1997
Pages
5947 - 5950
Database
ISI
SICI code
0021-9193(1997)179:18<5947:AORGBT>2.0.ZU;2-Z
Abstract
R1162 is a representative member of the broad-host-range IncQ group of multicopy plasmids. Lower-copy-number derivatives of R1162 were const ructed in vitro and shown to be unstable, indicating that partitioning of plasmid copies at cell division is due to random distribution and not to an active partitioning mechanism, However, the normal copy numb er of R1162 reduces cell fitness during growth in broth and favors the emergence of unstable, lower-copy-number variants. As a result, plasm id-borne antibiotic resistance genes active at a low copy number event ually result in plasmid loss during periods of no selection. We argue that the maintenance of R1162 in a population requires a gene that is selected only at high levels. This reduces the potential for acquiring genes from other R factors and could explain the limited variety of a ntibiotic resistance genes contained by naturally occurring IncQ plasm ids.