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Mendonca, Deborah C. ; Morais, Sinara T. B. ; Ciol, Heloisa ; Pinto, Andressa P. A. ; Leonardo, Diego A. ; Pereira, Humberto D'Muniz ; Valadares, Napoleao F. ; V. Portugal, Rodrigo ; Klaholz, Bruno P. ; Garratt, Richard C. ; Araujo, Ana P. U.

• Tipo de documento: Artigo Científico
• Fonte: Journal of Molecular Biology; v. 436, n. 16, p. 20-pg., 2024-07-10.

Resumo

Septins are filamentous nucleotide-binding proteins which can associate with membranes in a curvature- dependent manner leading to structural remodelling and barrier formation. Ciona intestinalis, a model for exploring the development and evolution of the chordate lineage, has only four septin-coding genes within its genome. These represent orthologues of the four classical mammalian subgroups, making it a minimalist non-redundant model for studying the modular assembly of septins into linear oligomers and thereby filamentous polymers. Here, we show that C. intestinalis septins present a similar biochemistry to their human orthologues and also provide the cryo-EM structures of an octamer, a hexamer and a tetrameric sub-complex. The octamer, which has the canonical arrangement (2-6-7-9-9-7-6-2) clearly shows an exposed NC-interface at its termini enabling copolymerization with hexamers into mixed filaments. Indeed, only combinations of septins which had Ci SEPT2 occupying the terminal position were able to assemble into filaments via NC-interface association. The Ci SEPT7- Ci SEPT9 tetramer is the smallest septin particle to be solved by Cryo-EM to date and its good resolution (2.7 angstrom) provides a well-defined view of the central NC-interface. On the other hand, the Ci SEPT7- Ci SEPT9 G-interface shows signs of fragility permitting toggling between hexamers and octamers, similar to that seen in human septins but not in yeast. The new structures provide insights concerning the molecular mechanism for cross-talk between adjacent interfaces. This indicates that C. intestinalis may represent a valuable tool for future studies, fulfilling the requirements of a complete but simpler system to understand the mechanisms behind the assembly and dynamics of septin filaments. (c) 2024 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies. (AU)

• Processo FAPESP: 21/10247-0 - Single-particle and sub-tomogram analysis of septin filaments
• Beneficiário: Deborah Cezar Mendonça
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado
• Processo FAPESP: 21/08158-9 - Estudos cristalográficos de septinas, seus domínios e seus complexos
• Beneficiário: Diego Antonio Leonardo Cabrejos
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 23/06866-1 - Aplicação da microscopia eletrônica de transmissão e análise de partículas isoladas no estudo estrutural de complexos de septinas.
• Beneficiário: Deborah Cezar Mendonça
• Modalidade de apoio: Bolsas no Brasil - Programa Capacitação - Treinamento Técnico
• Processo FAPESP: 18/20209-5 - Estudos estruturais sobre a montagem de complexos de septinas por microscopia eletrônica de transmissão e análise de partículas isoladas
• Beneficiário: Deborah Cezar Mendonça
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 20/02897-1 - Filamentos de septinas: estrutura, polimerização e atuação em patologias
• Beneficiário: Richard Charles Garratt
• Modalidade de apoio: Auxílio à Pesquisa - Temático