{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/78399"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/78399","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Genetic Engineering of Functional Large Amyloid Fibers","abstract":"\"Template\" and \"adder\" proteins can be genetically encoded to produce large amyloid fibers when mixed together. Escherichia coli is used to clone a \"template\" protein, Gd20, which will cooperatively self-assemble with two \"adder\" proteins, P7Q and P7S, to yield two different large amyloid fibers. Atomic force microscopy (AFM) is used to image the fibers and AFM tip approach/retraction force is used to quantify molecular packing in the fibers. Glutamine (Q)-containing P7Q and serine (S)-containing P7S both have the same hydrophobic core, charge, and hydrogen bonding potential. However, P7Q is highly alpha-helical while P7S contains a beta-sheet core. After 72 hours, the Gd20:P7Q template:adder protein mixture produces tightly packed ~0.3 μm high and ~1.9 μm wide fibers that exhibit a low retraction force of ~44 nN after indentation. The Gd20:P7S mixture produces larger ~1.1 μm high and ~9.7 μm wide fibers exhibiting a much higher retraction force of ~503 nN showing they are much less molecularly packed. These results indicate that the adder protein alpha-helical character is important for self-assembly and molecular packing inside of the large amyloid fiber. The experimental results show that large amyloid fibers with predictable size and mechanical properties can be anticipated and encoded at the genetic level.","abstract_html":""Template" and "adder" proteins can be genetically encoded to produce large amyloid fibers when mixed together. Escherichia coli is used to clone a "template" protein, Gd20, which will cooperatively self-assemble with two "adder" proteins, P7Q and P7S, to yield two different large amyloid fibers. Atomic force microscopy (AFM) is used to image the fibers and AFM tip approach/retraction force is used to quantify molecular packing in the fibers. Glutamine (Q)-containing P7Q and serine (S)-containing P7S both have the same hydrophobic core, charge, and hydrogen bonding potential. However, P7Q is highly alpha-helical while P7S contains a beta-sheet core. After 72 hours, the Gd20:P7Q template:adder protein mixture produces tightly packed ~0.3 μm high and ~1.9 μm wide fibers that exhibit a low retraction force of ~44 nN after indentation. The Gd20:P7S mixture produces larger ~1.1 μm high and ~9.7 μm wide fibers exhibiting a much higher retraction force of ~503 nN showing they are much less molecularly packed. These results indicate that the adder protein alpha-helical character is important for self-assembly and molecular packing inside of the large amyloid fiber. The experimental results show that large amyloid fibers with predictable size and mechanical properties can be anticipated and encoded at the genetic level.","abstract_has_math":false,"creators":["Roth, David Eugene"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Biological Systems Engineering","degree_department":"Biological Systems Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Barone, Justin R."],"committee_members":["Ruder, Warren Christopher","Davalos, Rafael V."],"year":2016,"date_issued":"2016-01-29","date_published":"2016-01-29","updated_at":"2026-07-22T22:19:48Z","subjects":["self-assembly","genetic encoding","fibril","fiber","amyloid","cellular expression","point spectroscopy","nanoindentation","molecular packing","retraction force","AFM"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:7136"],"render_values":[{"text":"vt_gsexam:7136","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/78399","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Barone, Justin R."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Ruder, Warren Christopher","Davalos, Rafael V."]},{"key":"dc:contributor.department","label":"Department","values":["Biological Systems Engineering"]},{"key":"dc:creator","label":"Author","values":["Roth, David Eugene"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2017-07-23T06:00:13Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2017-07-23T06:00:13Z"]},{"key":"dc:date.issued","label":"Date","values":["2016-01-29"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biological Systems Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["self-assembly","genetic encoding","fibril","fiber","amyloid","cellular expression","point spectroscopy","nanoindentation","molecular packing","retraction force","AFM"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:7136"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/78399"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["\"Template\" and \"adder\" proteins can be genetically encoded to produce large amyloid fibers when mixed together. Escherichia coli is used to clone a \"template\" protein, Gd20, which will cooperatively self-assemble with two \"adder\" proteins, P7Q and P7S, to yield two different large amyloid fibers. Atomic force microscopy (AFM) is used to image the fibers and AFM tip approach/retraction force is used to quantify molecular packing in the fibers. Glutamine (Q)-containing P7Q and serine (S)-containing P7S both have the same hydrophobic core, charge, and hydrogen bonding potential. However, P7Q is highly alpha-helical while P7S contains a beta-sheet core. After 72 hours, the Gd20:P7Q template:adder protein mixture produces tightly packed ~0.3 μm high and ~1.9 μm wide fibers that exhibit a low retraction force of ~44 nN after indentation. The Gd20:P7S mixture produces larger ~1.1 μm high and ~9.7 μm wide fibers exhibiting a much higher retraction force of ~503 nN showing they are much less molecularly packed. These results indicate that the adder protein alpha-helical character is important for self-assembly and molecular packing inside of the large amyloid fiber. The experimental results show that large amyloid fibers with predictable size and mechanical properties can be anticipated and encoded at the genetic level."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["Genetic Engineering of Functional Large Amyloid Fibers"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Barone, Justin R."],"dc:contributor.committeemember":["Ruder, Warren Christopher","Davalos, Rafael V."],"dc:contributor.department":["Biological Systems Engineering"],"dc:creator":["Roth, David Eugene"],"dc:date.accessioned":["2017-07-23T06:00:13Z"],"dc:date.available":["2017-07-23T06:00:13Z"],"dc:date.issued":["2016-01-29"],"dc:description.abstract":["\"Template\" and \"adder\" proteins can be genetically encoded to produce large amyloid fibers when mixed together. Escherichia coli is used to clone a \"template\" protein, Gd20, which will cooperatively self-assemble with two \"adder\" proteins, P7Q and P7S, to yield two different large amyloid fibers. Atomic force microscopy (AFM) is used to image the fibers and AFM tip approach/retraction force is used to quantify molecular packing in the fibers. Glutamine (Q)-containing P7Q and serine (S)-containing P7S both have the same hydrophobic core, charge, and hydrogen bonding potential. However, P7Q is highly alpha-helical while P7S contains a beta-sheet core. After 72 hours, the Gd20:P7Q template:adder protein mixture produces tightly packed ~0.3 μm high and ~1.9 μm wide fibers that exhibit a low retraction force of ~44 nN after indentation. The Gd20:P7S mixture produces larger ~1.1 μm high and ~9.7 μm wide fibers exhibiting a much higher retraction force of ~503 nN showing they are much less molecularly packed. These results indicate that the adder protein alpha-helical character is important for self-assembly and molecular packing inside of the large amyloid fiber. The experimental results show that large amyloid fibers with predictable size and mechanical properties can be anticipated and encoded at the genetic level."],"dc:description.degree":["Master of Science"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:7136"],"dc:identifier.uri":["http://hdl.handle.net/10919/78399"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["self-assembly","genetic encoding","fibril","fiber","amyloid","cellular expression","point spectroscopy","nanoindentation","molecular packing","retraction force","AFM"],"dc:title":["Genetic Engineering of Functional Large Amyloid Fibers"],"dc:type":["Thesis"],"thesis:degree_discipline":["Biological Systems Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:48Z"}