File Download
  Links for fulltext
     (May Require Subscription)
Supplementary

postgraduate thesis: Structural and functional studies of human APPL1-APPL2 BAR-PH heterodimer, APPL2 BAR-PH homodimer, and lanthionine synthetase component C-like protein 2

TitleStructural and functional studies of human APPL1-APPL2 BAR-PH heterodimer, APPL2 BAR-PH homodimer, and lanthionine synthetase component C-like protein 2
Authors
Issue Date2012
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Chen, Y. [陈宇杰]. (2012). Structural and functional studies of human APPL1-APPL2 BAR-PH heterodimer, APPL2 BAR-PH homodimer, and lanthionine synthetase component C-like protein 2. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5043419
AbstractAPPL BAR-PH heterodimer and APPL2 BAR-PH homodimer The APPL (Adaptor protein containing PH domain, PTB domain and Leucine zipper) family are adaptor proteins with only two isoforms, APPL1 and APPL2. They bind to early endosomes with a small GTPase, Rab5, and mediate the interactions between various receptors and downstream signaling components, thus functioning in many signaling pathways evoked by adiponectin, insulin, FSH, EGF, and so on. However, evidences have shown APPL1 and APPL2 should perform some opposite functions, which cannot be simply explained by the functional differences attributed to their PTB domains. We hypothesize that the heterodimerization of APPL1 and APPL2’s BAR domains may account for their opposing functions. The crystal structure of APPL BAR-PH heterodimer was solved to resolution 2.8 Å. Its overall structure exhibits crescent shape with a larger curvature radius of 76 Å, compared to 55 Å of the APPL1 BAR-PH homodimer. And the crystal structure APPL2 BAR-PH homodimer was solve to resolution 3.3 Å. The overall structure of APPL2 BAR-PH homodimer is very similar to that of APPL BAR-PH heterodimer, but shows greater difference in curvature to the APPL1 BAR-PH homodimer structure. The concave side of APPL BAR-PH heterodimer and APPL2 BAR-PH homodimer all possess less positive charge than the APPL1 BAR-PH homodimer. Structural analysis reveals that leucine patches at the dimer interface may account for the formation of dimeric curve with certain curvature. Consequently, APPL2 BAR is able to enforce the curvature reduction to APPL1 BAR upon heterodimerization. In conclusion, the alterations of curvature and electrostasis are responsible for the modulation of endosome binding specificity and can elucidate the opposite roles of APPL1 and APPL2. LanCL2 LanCL2 is a member of Lanthionine synthetase component C-like family. In human, LanCL2 binds to lanthionine derivatives and glutathione, participating in keeping intracellular reducing state. By binding to absiscic acid (ABA), LanCL2 is indispensible for the ABA-stimulated adipogenesis, insulin release, glucose homeostasis, and inflammatory response. It is also implicated in anticancer drug resistance. All these functions underscore the importance of LanCL2 in the diseases like diabetes, inflammation, and cancer. The crystal structure of LanCL2 was solved to resolution 1.8 Å. The overall structure displays canonical double-layer α-barrel. The major differences from LanCL1 lay in the loops on the barrel top, which are implicated in various substrate bindings. A zinc-coordinating pocket was found among the loops, with conserved amino acid residues of distinct conformation. The electrostatic surface shows remarkable differences compared to that of LanCL1, suggesting that it may contribute to distinct substrate binding profile. Future implications APPL proteins and LanCL proteins are all involved in the regulation of metabolism, such as glucose uptake, fatty acid oxidation, and insulin secretion, and play roles in diseases like obesity and type 2 diabete. Structural and functional studies of these proteins can provide insights into the molecular mechanisms and clues for related therapeutic approaches.
DegreeDoctor of Philosophy
SubjectCarrier proteins
Cellular signal transduction
Dept/ProgramPhysiology
Persistent Identifierhttp://hdl.handle.net/10722/197138

 

DC FieldValueLanguage
dc.contributor.authorChen, Yujie-
dc.contributor.author陈宇杰-
dc.date.accessioned2014-05-12T07:30:30Z-
dc.date.available2014-05-12T07:30:30Z-
dc.date.issued2012-
dc.identifier.citationChen, Y. [陈宇杰]. (2012). Structural and functional studies of human APPL1-APPL2 BAR-PH heterodimer, APPL2 BAR-PH homodimer, and lanthionine synthetase component C-like protein 2. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5043419-
dc.identifier.urihttp://hdl.handle.net/10722/197138-
dc.description.abstractAPPL BAR-PH heterodimer and APPL2 BAR-PH homodimer The APPL (Adaptor protein containing PH domain, PTB domain and Leucine zipper) family are adaptor proteins with only two isoforms, APPL1 and APPL2. They bind to early endosomes with a small GTPase, Rab5, and mediate the interactions between various receptors and downstream signaling components, thus functioning in many signaling pathways evoked by adiponectin, insulin, FSH, EGF, and so on. However, evidences have shown APPL1 and APPL2 should perform some opposite functions, which cannot be simply explained by the functional differences attributed to their PTB domains. We hypothesize that the heterodimerization of APPL1 and APPL2’s BAR domains may account for their opposing functions. The crystal structure of APPL BAR-PH heterodimer was solved to resolution 2.8 Å. Its overall structure exhibits crescent shape with a larger curvature radius of 76 Å, compared to 55 Å of the APPL1 BAR-PH homodimer. And the crystal structure APPL2 BAR-PH homodimer was solve to resolution 3.3 Å. The overall structure of APPL2 BAR-PH homodimer is very similar to that of APPL BAR-PH heterodimer, but shows greater difference in curvature to the APPL1 BAR-PH homodimer structure. The concave side of APPL BAR-PH heterodimer and APPL2 BAR-PH homodimer all possess less positive charge than the APPL1 BAR-PH homodimer. Structural analysis reveals that leucine patches at the dimer interface may account for the formation of dimeric curve with certain curvature. Consequently, APPL2 BAR is able to enforce the curvature reduction to APPL1 BAR upon heterodimerization. In conclusion, the alterations of curvature and electrostasis are responsible for the modulation of endosome binding specificity and can elucidate the opposite roles of APPL1 and APPL2. LanCL2 LanCL2 is a member of Lanthionine synthetase component C-like family. In human, LanCL2 binds to lanthionine derivatives and glutathione, participating in keeping intracellular reducing state. By binding to absiscic acid (ABA), LanCL2 is indispensible for the ABA-stimulated adipogenesis, insulin release, glucose homeostasis, and inflammatory response. It is also implicated in anticancer drug resistance. All these functions underscore the importance of LanCL2 in the diseases like diabetes, inflammation, and cancer. The crystal structure of LanCL2 was solved to resolution 1.8 Å. The overall structure displays canonical double-layer α-barrel. The major differences from LanCL1 lay in the loops on the barrel top, which are implicated in various substrate bindings. A zinc-coordinating pocket was found among the loops, with conserved amino acid residues of distinct conformation. The electrostatic surface shows remarkable differences compared to that of LanCL1, suggesting that it may contribute to distinct substrate binding profile. Future implications APPL proteins and LanCL proteins are all involved in the regulation of metabolism, such as glucose uptake, fatty acid oxidation, and insulin secretion, and play roles in diseases like obesity and type 2 diabete. Structural and functional studies of these proteins can provide insights into the molecular mechanisms and clues for related therapeutic approaches.-
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subject.lcshCarrier proteins-
dc.subject.lcshCellular signal transduction-
dc.titleStructural and functional studies of human APPL1-APPL2 BAR-PH heterodimer, APPL2 BAR-PH homodimer, and lanthionine synthetase component C-like protein 2-
dc.typePG_Thesis-
dc.identifier.hkulb5043419-
dc.description.thesisnameDoctor of Philosophy-
dc.description.thesislevelDoctoral-
dc.description.thesisdisciplinePhysiology-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.5353/th_b5043419-
dc.date.hkucongregation2013-

Export via OAI-PMH Interface in XML Formats


OR


Export to Other Non-XML Formats