S. Datta et Dk. Choudhuri, CHARACTERIZATION OF A LARGE PLASMID ENCODING FOR LIPOPOLYSACCHARIDE SYNTHESIS, DRUG-RESISTANCE AND VIRULENCE CHARACTERS IN SHIGELLA-DYSENTERIAE TYPE-1, Biochemical archives, 9(4), 1993, pp. 287-296
A 120 kb plasmid was transfered from N'-methyl-N'-nitro-N'-nitrosoguan
idine treated Shigella dysenteriae type 1 (Strain Dt 66, Am(r) Cm(r) T
c(r) Nal(s) ) to a plasmidless E.coli K12 KL318 (Am(s) Cm(s) Tc(s) Nal
(r) ) strain by conjugation. The Ampicillin, Chloramphenicol, Tetracyc
line resistant (Am(r) Cm(r), Tc(r) ) characters of transconjugants wer
e found to be encoded by the 120 kb-plasmid. On 0.7% agarose gel elect
rophoresis, localization of 120 kb plasmids of transconjugant & donor
were found at the same position. In lipopolysaccharide (LPS) biosynthe
sis studies, six fold, more LPS was recovered from transconjugant then
the recipient. Similarly in SDS-PAGE analysis, the donor showed a cha
racteristic ladder like LPS-bands in the molar mass of 67 kD to 10 kD.
However, the transconjugants revealed only 38-kD LPS band and recipie
nt strain did not show any band. In virulence studies, both the donor
and transconjugants showed adherence to HeLa cells but transconjugants
exhibited no itracellular invasion. Additionally, transconjugants fai
led to produce keratoconjunctivities in guineapig whereas the same was
performed by the donor (Shigella dysenteriae type 1).