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G₁ la ciclina-Cdk promueve la entrada en el ciclo celular a través de la fosforilación localizada de la ARN

Mardo Kõivomägi¹, Matthew P Swaffer¹, Jonathan J Turner¹

¹Department of Biology, Stanford University, Stanford, CA 94305, USA.

Science (New York, N.Y.)

|October 14, 2021

Resumen

La división celular de la levadura en ciernes es desencadenada por Cln3-Cdk1, que fosforila la ARN polimerasa II, no Whi5. Esto promueve la transcripción en promotores clave, vinculando el ciclo celular y la regulación transcripcional.

Área de la Ciencia:

Biología molecular
Biología celular
La bioquímica

Sus antecedentes:

La iniciación de la división celular implica que las cinasas dependientes de la ciclina (Cdks) inactiven los inhibidores de la transcripción.
En la levadura en ciernes, se pensó que el complejo G1 ciclina Cln3-Cdk1 fosforilaba Whi5, liberando SBF y comprometiendo a las células a la división.

Objetivo del estudio:

Investigar el mecanismo preciso por el cual Cln3-Cdk1 inicia la división celular en la levadura en ciernes.
Aclarar el papel de la fosforilación de Whi5 en el compromiso del ciclo celular.
Explorar el vínculo entre la progresión del ciclo celular y la regulación de la transcripción.

Principales métodos:

Ensayos bioquímicos para probar Whi5 como sustrato para Cln3-Cdk1.
Análisis del sitio de fosforilación de la subunidad Rpb1 de ARN polimerasa II.
Experimentos genéticos que incluyen el reclutamiento sintético de quinasas a promotores.

Principales resultados:

Se encontró que Whi5 es un pobre sustrato para Cln3-Cdk1.
Cln3-Cdk1 fosforila directamente la posición S5 de las repeticiones de heptapéptido C-terminal de Rpb1.
Cln3-Cdk1 se une a promotores regulados por SBF, y su función puede ser imitada por Ccl1-Kin28 cuando está dirigida a SBF.

Conclusiones:

Cln3-Cdk1 inicia la división celular mediante la fosforilación de Rpb1 en promotores regulados por SBF, promoviendo así la transcripción.
Este mecanismo difumina la distinción entre el ciclo celular y los CDK de transcripción.
Los hallazgos ponen de relieve una antigua relación entre el control del ciclo celular y los procesos de transcripción.

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