Table 1 Bacterial strains and plasmids used in this study

R. etli strains

 CFN 42

Wild type

[29]

 CE3

Spontaneous Sm^r mutant of R, etli CFN 42 Nal^r

[31]

 CMS310

R. etli CE3 otsAch::ΩNal^rSm^rSpc^r

This study

E. coli strain

 DH5α

supE44 Δ (lac)U169 ϕ80d lacZΔM15 hsdR17 recA1 endA1 gyrA96 thi-1 relA1; host for DNA manipulations

[35]

Plasmids

 pSK(-)

Cloning vector; Ap^r

Stratagene

 pUC19-301

Cloning vector, Ap^r

J. Onofre, Personal Communication

 pHP45Ω

pBR322 derivative carrying the Ω cassette; Ap^rSm^rSp^r

[36]

 pRK600

Helper plasmid; Cm^rtra

[37]

 pJQ200-SK

Suicide vector; Gm^rmobsac

[38]

 pMotsA1

4.2-kb blunt fragment from R. etli CE3 genome (containing frk, otsAch, pgi) cloned into pUC19301 in Eco RV; Apr

This study

 pMotsA4

4,1-kb Bgl II-Xba I fragment from pMotsA1 cloned into pSK in Bam HI-Xba I; Ap^r

This study

 pMotsA5

pMotsA4 derivative containing an Bgl II recognition site within otsAch; Ap^r

This study

 pMotsA6

pMotsA5 derivative with Ω casete within otsAch; Ap^rSm^rSpc^r

This study

 pMotsA7

6.1-kb Apa I-Xba I fragment from pMotsA6 (containing frk,otsAch, pgi) cloned into pJQ200-SK; Gm^rSm^rSpc^r

This study