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[[ | ==N-Terminal Domain of Bombyx mori Fibroin Mediates the Assembly of Silk in Response to pH Decrease== | ||
<StructureSection load='3ua0' size='340' side='right' caption='[[3ua0]], [[Resolution|resolution]] 3.00Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[3ua0]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Bombyx_mori Bombyx mori]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3UA0 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3UA0 FirstGlance]. <br> | |||
</td></tr><tr><td class="sblockLbl"><b>[[Non-Standard_Residue|NonStd Res:]]</b></td><td class="sblockDat"><scene name='pdbligand=MSE:SELENOMETHIONINE'>MSE</scene></td></tr> | |||
<tr><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">FIBH ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=7091 Bombyx mori])</td></tr> | |||
<tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3ua0 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3ua0 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=3ua0 RCSB], [http://www.ebi.ac.uk/pdbsum/3ua0 PDBsum]</span></td></tr> | |||
<table> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
Fibroins serve as the major building blocks of silk fiber. As the major component of fibroin, the fibroin heavy chain is a considerably large protein comprising N-terminal and C-terminal hydrophilic domains and 12 highly repetitive Gly-Ala-rich regions flanked by internal hydrophilic blocks. Here, we show the crystal structure of the fibroin N-terminal domain (FibNT) at pH 4.7, revealing a remarkable double-layered anti-parallel beta-sheet with each layer comprising two FibNT molecules entangled together. We also show that FibNT undergoes a pH-responsive conformational transition from random coil to beta-sheets at around pH 6.0. Dynamic light scattering demonstrates that FibNT tends to oligomerize as pH decreases to 6.0, and electron microscopy reveals micelle-like oligomers. Our results are consistent with the micelle assembly model of silk fibroin and, more importantly, show that the N-terminal domain in itself has the capacity to form micelle-like structures in response to pH decrease. Structural and mutagenesis analyses further reveal the important role of conserved acidic residues clustered in FibNT, such as Glu56 and Asp100, in preventing premature beta-sheet formation at neutral pH. Collectively, we suggest that FibNT functions as a pH-responsive self-assembly module that could prevent premature beta-sheet formation at neutral pH yet could initiate fibroin assembly as pH decreases along the lumen of the posterior silk gland to the anterior silk gland. | |||
N-Terminal Domain of Bombyx mori Fibroin Mediates the Assembly of Silk in Response to pH Decrease.,He YX, Zhang NN, Li WF, Jia N, Chen BY, Zhou K, Zhang J, Chen Y, Zhou CZ J Mol Biol. 2012 Mar 1. PMID:22387468<ref>PMID:22387468</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
== References == | |||
<references/> | |||
__TOC__ | |||
</StructureSection> | |||
== | |||
< | |||
[[Category: Bombyx mori]] | [[Category: Bombyx mori]] | ||
[[Category: Chen, B Y.]] | [[Category: Chen, B Y.]] | ||
Revision as of 09:04, 5 June 2014
N-Terminal Domain of Bombyx mori Fibroin Mediates the Assembly of Silk in Response to pH DecreaseN-Terminal Domain of Bombyx mori Fibroin Mediates the Assembly of Silk in Response to pH Decrease
Structural highlights
Publication Abstract from PubMedFibroins serve as the major building blocks of silk fiber. As the major component of fibroin, the fibroin heavy chain is a considerably large protein comprising N-terminal and C-terminal hydrophilic domains and 12 highly repetitive Gly-Ala-rich regions flanked by internal hydrophilic blocks. Here, we show the crystal structure of the fibroin N-terminal domain (FibNT) at pH 4.7, revealing a remarkable double-layered anti-parallel beta-sheet with each layer comprising two FibNT molecules entangled together. We also show that FibNT undergoes a pH-responsive conformational transition from random coil to beta-sheets at around pH 6.0. Dynamic light scattering demonstrates that FibNT tends to oligomerize as pH decreases to 6.0, and electron microscopy reveals micelle-like oligomers. Our results are consistent with the micelle assembly model of silk fibroin and, more importantly, show that the N-terminal domain in itself has the capacity to form micelle-like structures in response to pH decrease. Structural and mutagenesis analyses further reveal the important role of conserved acidic residues clustered in FibNT, such as Glu56 and Asp100, in preventing premature beta-sheet formation at neutral pH. Collectively, we suggest that FibNT functions as a pH-responsive self-assembly module that could prevent premature beta-sheet formation at neutral pH yet could initiate fibroin assembly as pH decreases along the lumen of the posterior silk gland to the anterior silk gland. N-Terminal Domain of Bombyx mori Fibroin Mediates the Assembly of Silk in Response to pH Decrease.,He YX, Zhang NN, Li WF, Jia N, Chen BY, Zhou K, Zhang J, Chen Y, Zhou CZ J Mol Biol. 2012 Mar 1. PMID:22387468[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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