细菌质粒复制拷贝数的调控 1)细菌质粒的拷贝数有两种:单拷贝,多拷贝 2)细菌质粒的复制利用的装置与染色体DNA的 复制是相同的,但质粒的复制独立于染色体 3)细菌质粒拷贝的控制有相对独立的调控机制 4)质粒的非兼容性调控与拷贝数调控有两种不 同的机制:反义RNA和重复子( Citron 5)染色体DNA复制是双向复制,质粒DNA复制是 单向复制
细菌质粒复制拷贝数的调控 1) 细菌质粒的拷贝数有两种:单拷贝, 多拷贝. 2) 细菌质粒的复制利用的装置与染色体DNA的 复制是相同的, 但质粒的复制独立于染色体.. 3) 细菌质粒拷贝的控制有相对独立的调控机制. 4) 质粒的非兼容性调控与拷贝数调控有两种不 同的机制: 反义RNA和重复子(iteron). 5) 染色体DNA复制是双向复制, 质粒DNA复制是 单向复制
非兼容性质粒复制调控 1. Incompatibility group: a set of plasmids that are unable to coexist in the same bacterial cell. Both plasmids have the same type of origin. Copy number is controlled: repressor(rNa D)that measures the concentration of origins. 2. CoEl plasmid as a model for copy number and compatibility system(ca 20 copies per cell ). Selfish plasmids with territorial rights(自私质粒具有领土主权)
非兼容性质粒复制调控 1. Incompatibility group: a set of plasmids that are unable to coexist in the same bacterial cell. Both plasmids have the same type of origin. Copy number is controlled: repressor (RNA I) that measures the concentration of origins. 2. ColE1 plasmid as a model for copy number and compatibility system. (ca. 20 copies per cell). Selfish plasmids with territorial rights (自私质粒具有领土主权)
Plasmid incompatibility is connected with copy nunber 非兼容性质粒复制抑制的机制 l. Primer RNA: 555 bases, starts upstream of the ori and extends into the ori a cleaved by rnase H(cuts RNA: DNA hybrids) b 3'OH of RNA serves as primer to initiate DNA synthesis c only cut by rNase h if it is not duplexed with antisense RNA (RNAD
Plasmid incompatibility is connected with copy number 非兼容性质粒复制抑制的机制: 1. Primer RNA: 555 bases, starts upstream of the ori and extends into the ori. a. cleaved by RNase H (cuts RNA:DNA hybrids) b. 3’ OH of RNA serves as primer to initiate DNA synthesis. c. only cut by RNase H if it is not duplexed with antisense RNA (RNA I)
Replication of ColEl plasrnid DNA-nulticopy control: Replication starts with transcription RNA lI is required for priming DNA synthesis RNa pOlymerase at the origin. Positive requlation 启动子1555 20 RNA I P- P- origIn RNA|启动子 Anti-sense RNA I(108 b) acts as a negative P- and p- are regulator promoters for the regulatory transcripts
origin P-II P-I Replication of ColE1 plasmid DNA-multicopy control; Replication starts with transcription RNA I RNA II Anti-sense RNA I (108 b) acts as a negative regulator RNA II is required for priming DNA synthesis at the origin. Positive regulation. P-I and P-II are promoters for the regulatory transcripts. -555 -20 RNA polymerase 启动子II 启动子I
Replication of ColE1 plasrnid DNA-rmulticopy control -555 265 20 P- ongIn P 复制引物 RNA-loop structure s required to RNA lI RNaseH stabilize the RNA DNA creates the persistent hybrid 5 3-terminus if loops are present
P-II origin Replication of ColE1 plasmid DNA-multicopy control RNA II 555 -20 5’ 3’ RNA-loop structure is required to stabilize the RNA:DNA persistent hybrid . RNaseH creates the 3’-terminus if loops are present. P- -265