Characterisation of two members of the Arabidopsis thaliana IRQ family of proteins : a nexus for membrane trafficking and the actin cytoskeleton
Autor(a) principal: | |
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Data de Publicação: | 2021 |
Idioma: | eng |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | http://hdl.handle.net/10451/53670 |
Resumo: | The spatiotemporal organisation of cells is essential for the correct performance of organisms, which implies a complex and highly regulated system. In eukaryotic cells, this aspect is of particular importance, with the cytoskeleton playing a key role as a determinant of cell architecture and function. Regarding plant cells, the actin cytoskeleton is involved in most developmental processes, regulating membrane trafficking, organelle movement, morphogenesis and the establishment and maintenance of cell polarity. The dynamics of the actin cytoskeleton are regulated by numerous actin-binding proteins (ABPs), that modulate the polymerisation/depolymerisation of filaments, mediate the transport of cellular components, contribute to the formation of higher-order actin structures, and serve as a bridge between the actin cytoskeleton and membrane structures in the cell. The NETWORKED (NET) proteins are a recently characterised, plant-specific superfamily of actin-binding proteins that serve as interfaces between the actin cytoskeleton and various cell membranes. Some members (NET3A, NET3C; NET4A, NET4B) share a conserved domain in the C-terminal region that has at its centre three conserved amino acids – isoleucine (I), arginine (R) and glutamine (Q) – and was thus termed the IRQ domain. A bioinformatics search resulted in a list of six additional proteins, with a high level of conservation in the central and flanking regions of the domain, designated IRQ1-6. The newly identified IRQs along with the aforementioned NETs were named the IRQ family. Rab proteins are part of the Ras superfamily of small guanosine triphosphatases (GTPases), which function as GDP/GTP regulated molecular switches and are widely known for their involvement in membrane trafficking; their role is to recruit effectors (e.g., motor proteins and tethering factors) that facilitate downstream membrane trafficking events. It has been shown in Arabidopsis thaliana that NET4A and NET4B interact with members of the RabG3 subfamily of Rab GTPases, RABG3A and RABG3F, and that the IRQ domain is responsible for this interaction. Further work determined that these NETs are true Rab effector proteins through the IRQ domain, which raised the hypothesis that the IRQ domain is a novel plant Rab interaction motif and that other IRQ domain-containing proteins may also be Rab effectors. Rab GTPases of the RabG subfamily, also referred to as Rab7 GTPases, are involved in a vesicular trafficking pathway to the vacuole, which starts from the trans-Golgi network (TGN) to the pre-vacuolar compartments/multivesicular bodies (PVCs/MVBs) and ends at the vacuole, with the sequential activation of GTPases Rab5 (corresponding to RabF subfamily) and Rab7. This thesis focussed on the functional characterisation of two members of the IRQ protein family in Arabidopsis, IRQ2 and IRQ3, as potential actin-binding proteins recruited by RabG3 GTPases to mediate vacuole-related membrane trafficking events. The experiments performed in this thesis demonstrated that IRQ2 and IRQ3 interact with RabG3 GTPases, RABG3A and RABG3F, similarly to what was observed for the NET4A and NET4B proteins, and it was possible to prove, at least in part, that this interaction is dependent on the IRQ domain. However, the interaction domain of these IRQs with Rab GTPases appears to include other elements along the proteins, as studies involving the N-terminal region seemed to demonstrate. In addition to these results, it was also observed that the IRQ2 and IRQ3 proteins are distributed in distinct patterns in the plant cell, which may be related to these proteins binding different forms of actin; however, this aspect requires additional experimental confirmation. |
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Characterisation of two members of the Arabidopsis thaliana IRQ family of proteins : a nexus for membrane trafficking and the actin cytoskeletonCitoesqueleto de actinaproteínas de ligação à actinatráfego de membranaRab GTPasesvacúoloActin cytoskeletonActin-binding proteinsmembrane traffickingvacuoleDomínio/Área Científica::Ciências Naturais::Ciências BiológicasThe spatiotemporal organisation of cells is essential for the correct performance of organisms, which implies a complex and highly regulated system. In eukaryotic cells, this aspect is of particular importance, with the cytoskeleton playing a key role as a determinant of cell architecture and function. Regarding plant cells, the actin cytoskeleton is involved in most developmental processes, regulating membrane trafficking, organelle movement, morphogenesis and the establishment and maintenance of cell polarity. The dynamics of the actin cytoskeleton are regulated by numerous actin-binding proteins (ABPs), that modulate the polymerisation/depolymerisation of filaments, mediate the transport of cellular components, contribute to the formation of higher-order actin structures, and serve as a bridge between the actin cytoskeleton and membrane structures in the cell. The NETWORKED (NET) proteins are a recently characterised, plant-specific superfamily of actin-binding proteins that serve as interfaces between the actin cytoskeleton and various cell membranes. Some members (NET3A, NET3C; NET4A, NET4B) share a conserved domain in the C-terminal region that has at its centre three conserved amino acids – isoleucine (I), arginine (R) and glutamine (Q) – and was thus termed the IRQ domain. A bioinformatics search resulted in a list of six additional proteins, with a high level of conservation in the central and flanking regions of the domain, designated IRQ1-6. The newly identified IRQs along with the aforementioned NETs were named the IRQ family. Rab proteins are part of the Ras superfamily of small guanosine triphosphatases (GTPases), which function as GDP/GTP regulated molecular switches and are widely known for their involvement in membrane trafficking; their role is to recruit effectors (e.g., motor proteins and tethering factors) that facilitate downstream membrane trafficking events. It has been shown in Arabidopsis thaliana that NET4A and NET4B interact with members of the RabG3 subfamily of Rab GTPases, RABG3A and RABG3F, and that the IRQ domain is responsible for this interaction. Further work determined that these NETs are true Rab effector proteins through the IRQ domain, which raised the hypothesis that the IRQ domain is a novel plant Rab interaction motif and that other IRQ domain-containing proteins may also be Rab effectors. Rab GTPases of the RabG subfamily, also referred to as Rab7 GTPases, are involved in a vesicular trafficking pathway to the vacuole, which starts from the trans-Golgi network (TGN) to the pre-vacuolar compartments/multivesicular bodies (PVCs/MVBs) and ends at the vacuole, with the sequential activation of GTPases Rab5 (corresponding to RabF subfamily) and Rab7. This thesis focussed on the functional characterisation of two members of the IRQ protein family in Arabidopsis, IRQ2 and IRQ3, as potential actin-binding proteins recruited by RabG3 GTPases to mediate vacuole-related membrane trafficking events. The experiments performed in this thesis demonstrated that IRQ2 and IRQ3 interact with RabG3 GTPases, RABG3A and RABG3F, similarly to what was observed for the NET4A and NET4B proteins, and it was possible to prove, at least in part, that this interaction is dependent on the IRQ domain. However, the interaction domain of these IRQs with Rab GTPases appears to include other elements along the proteins, as studies involving the N-terminal region seemed to demonstrate. In addition to these results, it was also observed that the IRQ2 and IRQ3 proteins are distributed in distinct patterns in the plant cell, which may be related to these proteins binding different forms of actin; however, this aspect requires additional experimental confirmation.Malhó, Rui Manuel dos SantosHussey, Patrick J.Repositório da Universidade de LisboaBraga, Teresa2023-01-01T01:31:43Z2021-122021-072021-12-01T00:00:00Zdoctoral thesisinfo:eu-repo/semantics/publishedVersionapplication/pdfhttp://hdl.handle.net/10451/53670TID:101579489enginfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2024-11-20T18:15:15Zoai:repositorio.ul.pt:10451/53670Portal AgregadorONGhttps://www.rcaap.pt/oai/openairemluisa.alvim@gmail.comopendoar:71602024-11-20T18:15:15Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse |
dc.title.none.fl_str_mv |
Characterisation of two members of the Arabidopsis thaliana IRQ family of proteins : a nexus for membrane trafficking and the actin cytoskeleton |
title |
Characterisation of two members of the Arabidopsis thaliana IRQ family of proteins : a nexus for membrane trafficking and the actin cytoskeleton |
spellingShingle |
Characterisation of two members of the Arabidopsis thaliana IRQ family of proteins : a nexus for membrane trafficking and the actin cytoskeleton Braga, Teresa Citoesqueleto de actina proteínas de ligação à actina tráfego de membrana Rab GTPases vacúolo Actin cytoskeleton Actin-binding proteins membrane trafficking vacuole Domínio/Área Científica::Ciências Naturais::Ciências Biológicas |
title_short |
Characterisation of two members of the Arabidopsis thaliana IRQ family of proteins : a nexus for membrane trafficking and the actin cytoskeleton |
title_full |
Characterisation of two members of the Arabidopsis thaliana IRQ family of proteins : a nexus for membrane trafficking and the actin cytoskeleton |
title_fullStr |
Characterisation of two members of the Arabidopsis thaliana IRQ family of proteins : a nexus for membrane trafficking and the actin cytoskeleton |
title_full_unstemmed |
Characterisation of two members of the Arabidopsis thaliana IRQ family of proteins : a nexus for membrane trafficking and the actin cytoskeleton |
title_sort |
Characterisation of two members of the Arabidopsis thaliana IRQ family of proteins : a nexus for membrane trafficking and the actin cytoskeleton |
author |
Braga, Teresa |
author_facet |
Braga, Teresa |
author_role |
author |
dc.contributor.none.fl_str_mv |
Malhó, Rui Manuel dos Santos Hussey, Patrick J. Repositório da Universidade de Lisboa |
dc.contributor.author.fl_str_mv |
Braga, Teresa |
dc.subject.por.fl_str_mv |
Citoesqueleto de actina proteínas de ligação à actina tráfego de membrana Rab GTPases vacúolo Actin cytoskeleton Actin-binding proteins membrane trafficking vacuole Domínio/Área Científica::Ciências Naturais::Ciências Biológicas |
topic |
Citoesqueleto de actina proteínas de ligação à actina tráfego de membrana Rab GTPases vacúolo Actin cytoskeleton Actin-binding proteins membrane trafficking vacuole Domínio/Área Científica::Ciências Naturais::Ciências Biológicas |
description |
The spatiotemporal organisation of cells is essential for the correct performance of organisms, which implies a complex and highly regulated system. In eukaryotic cells, this aspect is of particular importance, with the cytoskeleton playing a key role as a determinant of cell architecture and function. Regarding plant cells, the actin cytoskeleton is involved in most developmental processes, regulating membrane trafficking, organelle movement, morphogenesis and the establishment and maintenance of cell polarity. The dynamics of the actin cytoskeleton are regulated by numerous actin-binding proteins (ABPs), that modulate the polymerisation/depolymerisation of filaments, mediate the transport of cellular components, contribute to the formation of higher-order actin structures, and serve as a bridge between the actin cytoskeleton and membrane structures in the cell. The NETWORKED (NET) proteins are a recently characterised, plant-specific superfamily of actin-binding proteins that serve as interfaces between the actin cytoskeleton and various cell membranes. Some members (NET3A, NET3C; NET4A, NET4B) share a conserved domain in the C-terminal region that has at its centre three conserved amino acids – isoleucine (I), arginine (R) and glutamine (Q) – and was thus termed the IRQ domain. A bioinformatics search resulted in a list of six additional proteins, with a high level of conservation in the central and flanking regions of the domain, designated IRQ1-6. The newly identified IRQs along with the aforementioned NETs were named the IRQ family. Rab proteins are part of the Ras superfamily of small guanosine triphosphatases (GTPases), which function as GDP/GTP regulated molecular switches and are widely known for their involvement in membrane trafficking; their role is to recruit effectors (e.g., motor proteins and tethering factors) that facilitate downstream membrane trafficking events. It has been shown in Arabidopsis thaliana that NET4A and NET4B interact with members of the RabG3 subfamily of Rab GTPases, RABG3A and RABG3F, and that the IRQ domain is responsible for this interaction. Further work determined that these NETs are true Rab effector proteins through the IRQ domain, which raised the hypothesis that the IRQ domain is a novel plant Rab interaction motif and that other IRQ domain-containing proteins may also be Rab effectors. Rab GTPases of the RabG subfamily, also referred to as Rab7 GTPases, are involved in a vesicular trafficking pathway to the vacuole, which starts from the trans-Golgi network (TGN) to the pre-vacuolar compartments/multivesicular bodies (PVCs/MVBs) and ends at the vacuole, with the sequential activation of GTPases Rab5 (corresponding to RabF subfamily) and Rab7. This thesis focussed on the functional characterisation of two members of the IRQ protein family in Arabidopsis, IRQ2 and IRQ3, as potential actin-binding proteins recruited by RabG3 GTPases to mediate vacuole-related membrane trafficking events. The experiments performed in this thesis demonstrated that IRQ2 and IRQ3 interact with RabG3 GTPases, RABG3A and RABG3F, similarly to what was observed for the NET4A and NET4B proteins, and it was possible to prove, at least in part, that this interaction is dependent on the IRQ domain. However, the interaction domain of these IRQs with Rab GTPases appears to include other elements along the proteins, as studies involving the N-terminal region seemed to demonstrate. In addition to these results, it was also observed that the IRQ2 and IRQ3 proteins are distributed in distinct patterns in the plant cell, which may be related to these proteins binding different forms of actin; however, this aspect requires additional experimental confirmation. |
publishDate |
2021 |
dc.date.none.fl_str_mv |
2021-12 2021-07 2021-12-01T00:00:00Z 2023-01-01T01:31:43Z |
dc.type.driver.fl_str_mv |
doctoral thesis |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10451/53670 TID:101579489 |
url |
http://hdl.handle.net/10451/53670 |
identifier_str_mv |
TID:101579489 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
dc.source.none.fl_str_mv |
reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação instacron:RCAAP |
instname_str |
Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
instacron_str |
RCAAP |
institution |
RCAAP |
reponame_str |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
collection |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
repository.name.fl_str_mv |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
repository.mail.fl_str_mv |
mluisa.alvim@gmail.com |
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1817549194142941184 |