G3p: Difference between revisions
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==Structural Analysis== | ==Structural Analysis== | ||
<applet load='1g3p' size='350' frame='true' align='right' caption='D1 and D2 domains of g3p' /> | <applet load='1g3p' size='350' frame='true' align='right' caption='D1 and D2 domains of g3p(1g3p)' /> | ||
Five major papers will be discussed outlining the evolution of structure analysis of g3p. | Five major papers will be discussed outlining the evolution of structure analysis of g3p. | ||
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===D1 Domain=== | ===D1 Domain=== | ||
The first structure of g3p entered into the PDB was by Holliger and Riechmann in late 1996-early 1997<ref name="holliger 97"/>. | The first structure of g3p entered into the PDB was by Holliger and Riechmann in late 1996-early 1997<ref name="holliger 97"/>. | ||
The D1 domain consists of mostly beta sheets. Both Holliger and Riechmann as well as Lubkowski et al noted a <scene name='G3p/N_terminal_alpha_helix/1'>N terminal alpha helix</scene> in their respective publications<ref name="holliger 97"/><ref name="lubkowski"/>. This aside, five <scene name='G3p/Beta_strands/1'>beta strands</scene> arranged as a barrel-like motif, which participates with two other strands from second domain to make an antiparallel sheet. Disulfide bonds exist between Cys 7 and Cys 36 (left handed helix) and Cys 46 and Cys 53 (right handed hook) <ref name="lubkowski"/>. | The <scene name='G3p/D1_in_blue_spin/1'>D1 domain</scene> consists of mostly beta sheets. Both Holliger and Riechmann as well as Lubkowski et al noted a <scene name='G3p/N_terminal_alpha_helix/1'>N terminal alpha helix</scene> in their respective publications<ref name="holliger 97"/><ref name="lubkowski"/>. This aside, five <scene name='G3p/Beta_strands/1'>beta strands</scene> arranged as a barrel-like motif, which participates with two other strands from second domain to make an antiparallel sheet. Disulfide bonds exist between Cys 7 and Cys 36 (left handed helix) and Cys 46 and Cys 53 (right handed hook) <ref name="lubkowski"/>. | ||
===D2 Domain=== | ===D2 Domain=== | ||
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==Functional Implications== | ==Functional Implications== | ||
===Infectivity=== | ===Infectivity=== | ||
The function of the protein has a close correlation with its structural domains. The D1 domain interacts with TolA protein in the periplasm of the bacterial cell. <ref name="lubkowski"/><ref name="cabilly"/><ref name="holliger 99"/>. (The C terminal domain of TolA is the coreceptor for filamentous phage infection of E coli(Cell 90, 351-360 (1997)). The D2 domain binds to F pilus on the outer membrane of ''Escherichia coli'', however, it is also blocks TolA binding to D1 in the absence of the F pilus <ref name="chatellier"> PMID:10606756 </ref>. In fact, without the D2 domain, infectivity is very low<ref name="lubkowski"/>. It has been speculated that D2 interacts with the F pilus first, drawing the phage closer to the bacterial cell, thus allowing D1-TolA interactions to occur<ref name="holliger 99"/>. Chatellier et al suggest that the complex formed by D1 and D2 may prevent destruction of the protein from bacterial proteases, and upon binding the protein opens up and D3 can then reach the inner membrane of the bacteria<ref name="chatellier"/>. Lubkowski et al like the interaction between D1 and D2 to a horseshoe shaped molecule attributing hydrophobic molecules facing toward the center as stabilizing factors <ref name="lubkowski"/>. | The function of the protein has a close correlation with its structural domains. The D1 domain interacts with TolA protein in the periplasm of the bacterial cell. <ref name="lubkowski"/><ref name="cabilly"/><ref name="holliger 99"/>. (The C terminal domain of TolA is the coreceptor for filamentous phage infection of E coli(Cell 90, 351-360 (1997)). The D2 domain binds to F pilus on the outer membrane of ''Escherichia coli'', however, it is also blocks TolA binding to D1 in the absence of the F pilus <ref name="chatellier"> PMID:10606756 </ref>. In fact, without the D2 domain, infectivity is very low<ref name="lubkowski"/>. It has been speculated that D2 interacts with the F pilus first, drawing the phage closer to the bacterial cell, thus allowing D1-TolA interactions to occur<ref name="holliger 99"/>. Chatellier et al suggest that the complex formed by D1 and D2 may prevent destruction of the protein from bacterial proteases, and upon binding the protein opens up and D3 can then reach the inner membrane of the bacteria<ref name="chatellier"/>. Lubkowski et al like the interaction between D1 and D2 to a horseshoe shaped molecule attributing <scene name='G3p/Hydrophobic/1'>hydrophobic molecules </scene> facing toward the center as stabilizing factors <ref name="lubkowski"/>. | ||
{{STRUCTURE_1tol | PDB=1tol | SCENE= }} | {{STRUCTURE_1tol | PDB=1tol | SCENE= }} | ||
The function of D3 was elicited last. D3 domain “anchors” to F pilus (Chatellier et al) and is necessary for phage packaging (Holliger et al) | The function of D3 was elicited last. D3 domain “anchors” to F pilus (Chatellier et al) and is necessary for phage packaging (Holliger et al) | ||
