Difference between revisions of "Part:BBa K1378031"
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===Usage and Biology=== | ===Usage and Biology=== | ||
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| + | <p>Holin is a generic term to describe a group of small proteins produced by double-stranded DNA bacteriophage to trigger holes formation at the end of lytic cycle. In our project, we design our suicide switch based on the λ lysis model. The S holin, also called S<sub>105</sub>, encoded by S gene, a dual-start motif of λ phage, is an 105-amino-acid-residue CM protein with three transmembrane domains (TMD)<sup>[3]</sup>. S<sub>107</sub>, also called antiholin, is the other protein encoded by S gene, differing from the S holin only by the Met-Lys N-terminal extension. However, this difference confers to S<sub>107</sub> an extra positive charge, which prevents its TMD1 from inserting into the CM<sup>[4]</sup>. Additionally, as its name suggests, S<sub>107</sub> can bind to S105 and inhibit its function specifically<sup>[5]</sup>. In λ lysis system, S<sub>107</sub> and S<sub>105</sub> are encoded by S gene at ratio of approximately 1:2, which is defined by the two RNA structure, and if the amount of S<sub>107</sub> is increased relative to S<sub>105</sub>, the 'lysis time' will be delayed<sup>[6]</sup>. The inhibition function of S<sub>107</sub> can be subverted by collapsing proton motive force, which also allow insertion of TMD1 of S<sub>107</sub> into CM, instantly increasing the amount of active holin by making previously inactive S<sub>107</sub> - S<sub>105</sub> complexes functional <b>(Fig. 1)</b>.</p> | ||
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| + | <figure><img src="https://static.igem.org/mediawiki/2014/b/be/Peking2014zsy_holin.png"><figcaption><b>Figure 1. </b> The model for the membrane topology of S<sub>107</sub> and S<sub>105</sub>. S<sub>105</sub> consist of three transmembrane domains (TMD) with an N-out, C-in topology while S<sub>107</sub> only has two TMDs, caused by an extra positive charge conferred by Lys2. The S<sub>107</sub> can inhibit the function of S<sub>105</sub>, preventing it from forming holes in cell membrane. However, this inhibition can be subverted by the dissipation of proton motive force and in this case, S<sub>107</sub> will become active holin, accelerating the rate of pore formation.</figcaption></figure> | ||
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<span class='h3bb'>Sequence and Features</span> | <span class='h3bb'>Sequence and Features</span> | ||
Revision as of 00:39, 18 October 2014
Holin from lambda phage
Holin is a 105-amino-acid-residue cytoplasmic membrane protein with three transmembrane domains, naturally expressed by double-stranded lambada phage. Holin will oligomerize and form a hole on the inner membrane of host bacteria at a certain time at an allele-specific time. And then the formation of hole will help Endolysin, a kind of lysozyme, come out from cytoplasm to periplasm to degrade peptidoglycan and inhibit the respiration by eliminating proton gradient.
Sequence and Features
Assembly Compatibility:
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000COMPATIBLE WITH RFC[1000]