User:Nathan Harris/Tus: Difference between revisions

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'''Tus''' is a DNA binding protein involved in the termination of bi-directional replication in ''Escherichia coli''. Tus binds specifically to ''Ter'' sequences within the ''E. Coli'' genome forming a Tus- ''Ter'' complex which functions to trap replication forks. Tus binds to ''Ter'' sites as an asymmetric monomer creating a permissive and non-permissive face to allow for polar fork arrest.

'''Tus''' is a DNA binding protein involved in the termination of bi-directional replication in ''Escherichia coli''. Tus binds specifically to ''Ter'' sequences within the ''E. Coli'' genome forming a Tus- ''Ter'' complex which functions to trap replication forks. Tus binds to ''Ter'' sites as an asymmetric monomer creating a permissive and non-permissive face to allow for polar fork arrest <ref name = "Neylon"> "Neylon" Neylon, C., Kralicek, A. V., Hill, T.M. and Dixon, N.E. (2005) Replication Termination in Escherichia coli: Structure and Antihelicase Activity of the Tus-Ter Complex. Microbiology and Molecular Biology, 69 (3): 501-526.

</ref>.

=='''Biological role'''==

Multiple ''Ter'' sites (''TerA''- ''TerJ'') are located in regions destined for replication termination in ''E. coli''. Tus binds specifically to these 23bp ''Ter'' sites forming a Tus-''Ter'' complex <ref name = "Neylon"> "Neylon" Neylon, C., Kralicek, A. V., Hill, T.M. and Dixon, N.E. (2005) Replication Termination in Escherichia coli: Structure and Antihelicase Activity of the Tus-Ter Complex. Microbiology and Molecular Biology, 69 (3): 501-526.

Multiple ''Ter'' sites (''TerA''- ''TerJ'') are located in regions destined for replication termination in ''E. coli''. Tus binds specifically to these 23bp ''Ter'' sites forming a Tus-''Ter'' complex . This complex allows for the blocking of an approaching replication fork in one direction, the non-permissive face, but not from the other direction, the permissive face. The ability to halt the replication machinery at the non-permissive face is thought to involve the inhibition of DnaB Helicase, preventing it from unwinding DNA. DnaB inhibition has been proposed to occur either through protein-protein interactions between Tus and DnaB, or by a physical block provided by Protein-DNA interactions i.e. the Tus-''Ter'' complex <ref name = "Kamada"> Kamada, K., Horiuchi, T., Ohsumi, K., Shimamoto, N. and Morikawa, K. (1996) Structure of a replication-terminator protein complexed with DNA. Nature 383 (6681): 598-603.</ref>. Recent models suggest a potentially combination of these two mechanisms <ref name = "Kaplan"> Kaplan, D. L. and Bastia, D. (2009) Mechanisms of polar arrest of replication fork. Molecular biology, 72 (2): 279-285.</ref>. Evolution of this termination system has allowed for efficient replication by ''E. coli'' as it prevents any over expenditure of energy or time. Different replication proteins have been found in other model organisms, such as RTP in ''Bacillus subtilis''. Despite similar biological roles of RTP and Tus they have significantly different structures.

~~</ref>~~

. This complex allows for the blocking of an approaching replication fork in one direction, the non-permissive face, but not from the other direction, the permissive face. The ability to halt the replication machinery at the non-permissive face is thought to involve the inhibition of DnaB Helicase, preventing it from unwinding DNA. DnaB inhibition has been proposed to occur either through protein-protein interactions between Tus and DnaB, or by a physical block provided by Protein-DNA interactions i.e. the Tus-''Ter'' complex <ref name = "~~Neylon~~" />

. Recent models suggest a potentially combination of these two mechanisms. Evolution of this termination system has allowed for efficient replication by ''E. coli'' as it prevents any over expenditure of energy or time. Different replication proteins have been found in other model organisms, such as RTP in ''Bacillus subtilis''. Despite similar biological roles of RTP and Tus they have significantly different structures.

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Henderson, T., Niles, A., Valjavec-Gratian, M. and Hill, T. (2001) Site-directed mutagenesis and phylogenetic comparisons of Escherichia coli Tus protein: DNA-protein interactions alone cannot account for Tus activity. Molecular Genetics and Genomics, 265 (6): 941-953.

~~Kamada, K., Horiuchi, T., Ohsumi, K., Shimamoto, N. and Morikawa, K. (1996) Structure of a replication-terminator protein complexed with DNA. Nature 383 (6681): 598-603.~~

~~Kaplab, D. L. and Bastia, D. (2009) Mechanisms of polar arrest of replication fork. Molecular biology, 72 (2): 279-285.~~

Mulcair, M. D., Schaeffer, P. M., Oakley, A. J., Cross, H. F., Neylon, C., Hill, T. M. and Dixon, N .E. (2006) A molecular Mousetrap Determines Polarity of Termination of DNA Replication in E. coli. Cell 125: 1309-1319.

User:Nathan Harris/Tus: Difference between revisions

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@@ Line 1: / Line 1: @@
-'''Tus''' is a DNA binding protein involved in the termination of bi-directional replication in ''Escherichia coli''. Tus binds specifically to ''Ter'' sequences within the ''E. Coli'' genome forming a Tus- ''Ter'' complex which functions to trap replication forks. Tus binds to ''Ter'' sites as an asymmetric monomer creating a permissive and non-permissive face to allow for polar fork arrest.
+'''Tus''' is a DNA binding protein involved in the termination of bi-directional replication in ''Escherichia coli''. Tus binds specifically to ''Ter'' sequences within the ''E. Coli'' genome forming a Tus- ''Ter'' complex which functions to trap replication forks. Tus binds to ''Ter'' sites as an asymmetric monomer creating a permissive and non-permissive face to allow for polar fork arrest <ref name = "Neylon"> "Neylon" Neylon, C., Kralicek, A. V., Hill, T.M. and Dixon, N.E.  (2005) Replication Termination in Escherichia coli: Structure and Antihelicase Activity of the Tus-Ter Complex.  Microbiology and Molecular Biology, 69 (3): 501-526.
+</ref>.
 =='''Biological role'''==
-Multiple ''Ter'' sites (''TerA''- ''TerJ'') are located in regions destined for replication termination in ''E. coli''. Tus binds specifically to these 23bp ''Ter'' sites forming a Tus-''Ter'' complex <ref name = "Neylon"> "Neylon" Neylon, C., Kralicek, A. V., Hill, T.M. and Dixon, N.E.  (2005) Replication Termination in Escherichia coli: Structure and Antihelicase Activity of the Tus-Ter Complex.  Microbiology and Molecular Biology, 69 (3): 501-526.
+Multiple ''Ter'' sites (''TerA''- ''TerJ'') are located in regions destined for replication termination in ''E. coli''. Tus binds specifically to these 23bp ''Ter'' sites forming a Tus-''Ter'' complex . This complex allows for the blocking of an approaching replication fork in one direction, the non-permissive face, but not from the other direction, the permissive face.  The ability to halt the replication machinery at the non-permissive face is thought to involve the inhibition of DnaB Helicase, preventing it from unwinding DNA. DnaB inhibition has been proposed to occur either through protein-protein interactions between Tus and DnaB, or by a physical block provided by Protein-DNA interactions i.e. the Tus-''Ter'' complex <ref name = "Kamada"> Kamada, K., Horiuchi, T., Ohsumi, K., Shimamoto, N. and Morikawa, K.  (1996) Structure of a replication-terminator protein complexed with DNA.  Nature 383 (6681): 598-603.</ref>.  Recent models suggest a potentially combination of these two mechanisms <ref name = "Kaplan"> Kaplan, D. L. and Bastia, D.  (2009) Mechanisms of polar arrest of replication fork.  Molecular biology, 72 (2): 279-285.</ref>. Evolution of this termination system has allowed for efficient replication by ''E. coli'' as it prevents any over expenditure of energy or time.  Different replication proteins have been found in other model organisms, such as RTP in ''Bacillus subtilis''.  Despite similar biological roles of RTP and Tus they have significantly different structures.
-</ref>
-. This complex allows for the blocking of an approaching replication fork in one direction, the non-permissive face, but not from the other direction, the permissive face.  The ability to halt the replication machinery at the non-permissive face is thought to involve the inhibition of DnaB Helicase, preventing it from unwinding DNA. DnaB inhibition has been proposed to occur either through protein-protein interactions between Tus and DnaB, or by a physical block provided by Protein-DNA interactions i.e. the Tus-''Ter'' complex <ref name = "Neylon" />
-.  Recent models suggest a potentially combination of these two mechanisms. Evolution of this termination system has allowed for efficient replication by ''E. coli'' as it prevents any over expenditure of energy or time.  Different replication proteins have been found in other model organisms, such as RTP in ''Bacillus subtilis''.  Despite similar biological roles of RTP and Tus they have significantly different structures.
@@ Line 64: / Line 62: @@
 Henderson, T., Niles, A., Valjavec-Gratian, M. and Hill, T.  (2001) Site-directed mutagenesis and phylogenetic comparisons of Escherichia coli Tus protein: DNA-protein interactions alone cannot account for Tus activity.  Molecular Genetics and Genomics, 265 (6): 941-953.
-Kamada, K., Horiuchi, T., Ohsumi, K., Shimamoto, N. and Morikawa, K.  (1996) Structure of a replication-terminator protein complexed with DNA.  Nature 383 (6681): 598-603.
-Kaplab, D. L. and Bastia, D.  (2009) Mechanisms of polar arrest of replication fork.  Molecular biology, 72 (2): 279-285.
 Mulcair, M. D., Schaeffer, P. M., Oakley, A. J., Cross, H. F., Neylon, C., Hill, T. M. and Dixon, N .E.  (2006) A molecular Mousetrap Determines Polarity of Termination of DNA Replication in E. coli. Cell 125: 1309-1319.