G3p: Difference between revisions
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==Overview== | ==Overview== | ||
{{STRUCTURE_2g3p | PDB=2g3p | SCENE= }} | |||
Gene 3 protein (g3p pr pIII) is a minor coat protein found on the surface of filamentous bacteriophage <ref name="lubkowski"> PMID:9461080 </ref>. The protein consists of 406 amino acids divided into three domains interspaced with glycine linkers <ref name="lubkowski"/> <ref name="cabilly"> PMID:10596371 </ref>. Peptides or proteins can be fused to g3p and evaluated for binding or other properties. | Gene 3 protein (g3p pr pIII) is a minor coat protein found on the surface of filamentous bacteriophage <ref name="lubkowski"> PMID:9461080 </ref>. The protein consists of 406 amino acids divided into three domains interspaced with glycine linkers <ref name="lubkowski"/> <ref name="cabilly"> PMID:10596371 </ref>. Peptides or proteins can be fused to g3p and evaluated for binding or other properties. | ||
==Structural Analysis== | ==Structural Analysis== | ||
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This domain contains eight beta strands: six in a mixed beta sheet and two interacting with D1 antiparallel sheet (β6 and β13 <ref name="lubkowski"/>. The amino acids between β6 and β7 doesn’t have a specific motif but has stabilizing hydrophobic interactions with other parts of the domain <ref name="lubkowski"/>. Three hairpins exist in this domain: between β8 and β9, β9 and β10, and β10 and β11 (cis proline in the last hairpin) <ref name="lubkowski"/>. The final secondary structural element is an alpha helix that interacts with rest of the domain via hydrophobic interactions <ref name="lubkowski"/>. Of note, there is a cation-π interaction between His 191 and Phe 199. The C terminus of D2 has seven peptides, 3 of which are proline, 1 of which is <scene name='G3p/Pro_213_in_cis_conformation/1'>in the cis conformation</scene> <ref name="lubkowski"/>. | This domain contains eight beta strands: six in a mixed beta sheet and two interacting with D1 antiparallel sheet (β6 and β13 <ref name="lubkowski"/>. The amino acids between β6 and β7 doesn’t have a specific motif but has stabilizing hydrophobic interactions with other parts of the domain <ref name="lubkowski"/>. Three hairpins exist in this domain: between β8 and β9, β9 and β10, and β10 and β11 (cis proline in the last hairpin) <ref name="lubkowski"/>. The final secondary structural element is an alpha helix that interacts with rest of the domain via hydrophobic interactions <ref name="lubkowski"/>. Of note, there is a cation-π interaction between His 191 and Phe 199. The C terminus of D2 has seven peptides, 3 of which are proline, 1 of which is <scene name='G3p/Pro_213_in_cis_conformation/1'>in the cis conformation</scene> <ref name="lubkowski"/>. | ||
==Functional Implications== | ==Functional Implications== | ||
===Infectivity=== | ===Infectivity=== | ||
[[Image:F1_holliger_and_riechmann.jpg |frame|center|Figure Adapted from Holliger and Riechmann, 1997<ref name="holliger 97"> PMID:9032075 </ref>]] | |||
The linkers don’t have a specific purpose but appear to give the protein better flexibility providing optimal infectivity <ref name="lubkowski"/>. | The linkers don’t have a specific purpose but appear to give the protein better flexibility providing optimal infectivity <ref name="lubkowski"/>. | ||
N1 interacts with TolA protein anchoring it to bacterial cell. <ref name="lubkowski"/>( and Cabilly) see Riechmann and Holliger. The C terminal domain of TolA is the coreceptor for filamentous phage infection of E coli. Cell 90, 351-360 (1997) | N1 interacts with TolA protein anchoring it to bacterial cell. <ref name="lubkowski"/>( and Cabilly) see Riechmann and Holliger. The C terminal domain of TolA is the coreceptor for filamentous phage infection of E coli. Cell 90, 351-360 (1997) | ||
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Fusions to N terminus (no affect on infectivity), between D12 and D3 (100 fold reduction for peptide insertion, and a 1000 to 100,000 fold for noncovalently interacting peptides)(Chatellier et al) | Fusions to N terminus (no affect on infectivity), between D12 and D3 (100 fold reduction for peptide insertion, and a 1000 to 100,000 fold for noncovalently interacting peptides)(Chatellier et al) | ||
===Phage Display=== | ===Phage Display=== | ||
N terminus can be truncated and the peptide of choice can be inserted (Cabilly) | [[Image:wt_and_pIII.jpg |frame|right|Figure Adapted from Hill and Stockley et al, 1996 <ref name="hill"> PMID:8793867 </ref>]] N terminus can be truncated and the peptide of choice can be inserted (Cabilly) | ||
Insertions can also be done between D2 and D3 (H and R, 9032075) | Insertions can also be done between D2 and D3 (H and R, 9032075) | ||
