Resistance Plasmids(r-plasmids the most well studied plasmids onv The emergence of bacteria resistant to several antibiotics is IS medically Significant Resistance can be transferred via cell-to-cell contact 890 This could be one of the reasons for the rapid rise of multiply 75 resistant strains Plasmid recombination is one cml 725 mean by which multiply resistant organisms might have 50 first arisen Infectious nature of the r plasmids permits rapid spread of the characteristic through populations onT ter Typical example: plasmid R100
Resistance Plasmids (R-Plasmids): the most well studied plasmids • The emergence of bacteria resistant to several antibiotics is medically significant • Resistance can be transferred via cell-to-cell contact • This could be one of the reasons for the rapid rise of multiply resistant strains • Plasmid recombination is one mean by which multiply resistant organisms might have first arisen • Infectious nature of the R plasmids permits rapid spread of the characteristic through populations • Typical example: plasmid R100
The presence of multiple antibiotic resistance is due to the fact that a single r plasmid contains a variety of genes coding for different antibiotic inactivation enzymes I H H.NC-N NH Biochemical HⅡ N-CNH2 HO mechanism OH RNH of resistance CH3 CH, mediated by OH R plasmids CHO Streptomycin Hc一cHcL H N H 3 O,N HH OH Phosphorylation (In aminoglycoside antibiotics Adenylylation with free amino group, inactivation also by N-acetylation
The presence of multiple antibiotic resistance is due to the fact that a single R plasmid contains a variety of genes coding for different antibiotic inactiviation enzymes Biochemical mechanism of resistance mediated by R plasmids
8.5 Three main processes of genetic recombination in chromosome are transferred to a recipient celm a donor prokaryotes fragments of homologous DNA fror (1)Transformation, which involves donor dna free in the environment 2)Transduction, in which the donor dna transfer is mediated by a virus (3) Conjugation, in which the transfer involves cell to-cell contact and a conjugative plasmid in the donor ce elI
(1) Transformation, which involves donor DNA free in the environment (2) Transduction, in which the donor DNA transfer is mediated by a virus (3) Conjugation, in which the transfer involves cellto-cell contact and a conjugative plasmid in the donor cell 8.5 Three main processes of genetic recombination in prokaryotes fragments of homologous DNA from a donor chromosome are transferred to a recipient cell
81. DNA Transfer in Bacteria DNA Transfer in bacteria Donor Free DNA transformation DNA-containing virus transduction Donor cell o conjugation ●
DNA Transfer in Bacteria transformation transduction conjugation
8.5.1 Conjugation Conjugative plasmids possess genetic information to code for sex pili and for some proteins needed for DNA transfer. Rolling circle replication occurs for DNA transfer during conjugation F plasmid of E coli has the special property of being able to mobilize the chromosome so that it can be transferred during cell-to-cell contact
8.5.1 Conjugation • Conjugative plasmids possess genetic information to code for sex pili and for some proteins needed for DNA transfer. • Rolling circle replication occurs for DNA transfer during conjugation. F plasmid of E. coli has the special property of being able to mobilize the chromosome so that it can be transferred during cell-to-cell contact