Evidence for the association of NR1 plasmid DNA with inner membrane of proteus mirabilis

• Main Author: Stukes, James Bernard
• Format: Others
• Published: DigitalCommons@Robert W. Woodruff Library, Atlanta University Center 1986
• Subjects: Biology
• Online Access: http://digitalcommons.auctr.edu/dissertations/1539; http://digitalcommons.auctr.edu/cgi/viewcontent.cgi?article=3199&context=dissertations

The examination of exponent i ally grown Proteus mirabilis, in the absence and presence of chloramphenicol revealed NR1 plasmid DNA-membrane complexes when isolated on 10-30% neutral sucrose (CLOS) gradients. Subsequent analysis of CLOS generated pl asmid DNA-membrane fract ions on 30- 50% isopycnic step neutral slJcrose gradients indicated preferential association of the plasmid DNA with the inner cytoplasmic membrane. In addition, plasmid DNA-membrane complexes isolated by the Clewell-Helinski "cleared lysate" procedure indicated preferential association with the inner cytoplasmic membrane, as well. Agarose gel analysis of covalently closed circular (CCC) NR1, isolated from exponentially grown cultures of P. mirabilis in the presence of chloramphenicol revealed that the plasmid molecules maintained their composite structure of 60 Mdaltons, and did not undergo transitioning. Further, EcoR! restriction digest of these molecules confirmed the existence of NR1 plasmid DNA.