title: Npa3/ScGpn1 carboxy-terminal tail is dispensable for cell viability and RNA polymerase II nuclear targeting but critical for microtubule stability and function.
abstract: Genetic deletion of the essential GTPase Gpn1 or replacement of the endogenous gene by partial loss of function mutants in yeast is associated with multiple cellular phenotypes, including in all cases a marked cytoplasmic retention of RNA polymerase II (RNAPII). Global inhibition of RNAPII-mediated transcription due to malfunction of Gpn1 precludes the identification and study of other cellular function(s) for this GTPase. In contrast to the single Gpn protein present in Archaea, eukaryotic Gpn1 possesses an extension of approximately 100 amino acids at the C-terminal end of the GTPase domain. To determine the importance of this C-terminal extension in Saccharomyces cerevisiae Gpn1, we generated yeast strains expressing either C-terminal truncated (gpn1ΔC) or full-length ScGpn1. We found that ScGpn1ΔC was retained in the cell nucleus, an event physiologically relevant as gpn1ΔC cells contained a higher nuclear fraction of the RNAPII CTD phosphatase Rtr1. gpn1ΔC cells displayed an increased size, a delay in mitosis exit, and an increased sensitivity to the microtubule polymerization inhibitor benomyl at the cell proliferation level and two cellular events that depend on microtubule function: RNAPII nuclear targeting and vacuole integrity. These phenotypes were not caused by inhibition of RNAPII, as in gpn1ΔC cells RNAPII nuclear targeting and transcriptional activity were unaffected. These data, combined with our description here of a genetic interaction between GPN1 and BIK1, a microtubule plus-end tracking protein with a mitotic function, strongly suggest that the ScGpn1 C-terminal tail plays a critical role in microtubule dynamics and mitotic progression in an RNAPII-independent manner.
authors.affiliation: Instituto de Física, Universidad Autónoma de San Luis Potosí, Manuel Nava 6, Zona Univesitaria, C.P. 78290, San Luis Potosí, San Luis Potosí, Mexico.
authors.forename: Gehenna
authors.initials: G
authors.lastname: Guerrero-Serrano
authors.affiliation: Instituto de Física, Universidad Autónoma de San Luis Potosí, Manuel Nava 6, Zona Univesitaria, C.P. 78290, San Luis Potosí, San Luis Potosí, Mexico.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Castanedo
authors.affiliation: Instituto de Física, Universidad Autónoma de San Luis Potosí, Manuel Nava 6, Zona Univesitaria, C.P. 78290, San Luis Potosí, San Luis Potosí, Mexico.
authors.forename: Gema R
authors.initials: GR
authors.lastname: Cristóbal-Mondragón
authors.affiliation: IPICYT, División de Biología Molecular, Camino a la Presa San José 2055, C.P. 78216, San Luis Potosí, San Luis Potosí, Mexico.
authors.forename: Javier
authors.initials: J
authors.lastname: Montalvo-Arredondo
authors.affiliation: IPICYT, División de Biología Molecular, Camino a la Presa San José 2055, C.P. 78216, San Luis Potosí, San Luis Potosí, Mexico.
authors.forename: Lina
authors.initials: L
authors.lastname: Riego-Ruíz
authors.affiliation: LANGEBIO: Laboratorio Nacional de Genomica para la Biodiversidad, Km 9.6 Libramiento Norte Carretera León, C.P. 36821 Irapuato, Guanajuato, Mexico.
authors.forename: Alexander
authors.initials: A
authors.lastname: DeLuna
authors.affiliation: IPICYT, División de Biología Molecular, Camino a la Presa San José 2055, C.P. 78216, San Luis Potosí, San Luis Potosí, Mexico.
authors.forename: Alejandro
authors.initials: A
authors.lastname: De Las Peñas
authors.affiliation: IPICYT, División de Biología Molecular, Camino a la Presa San José 2055, C.P. 78216, San Luis Potosí, San Luis Potosí, Mexico.
authors.forename: Irene
authors.initials: I
authors.lastname: Castaño
authors.affiliation: Instituto de Física, Universidad Autónoma de San Luis Potosí, Manuel Nava 6, Zona Univesitaria, C.P. 78290, San Luis Potosí, San Luis Potosí, Mexico. Electronic address: mcalera@ifisica.uaslp.mx.
authors.forename: Mónica R
authors.initials: MR
authors.lastname: Calera
authors.affiliation: Instituto de Física, Universidad Autónoma de San Luis Potosí, Manuel Nava 6, Zona Univesitaria, C.P. 78290, San Luis Potosí, San Luis Potosí, Mexico. Electronic address: rsanchez@ifisica.uaslp.mx.
authors.forename: Roberto
authors.initials: R
authors.lastname: Sánchez-Olea
mesh_terms: D001542:Benomyl / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D050296:Microbial Viability; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D000072417:Protein Domains; D012319:RNA Polymerase II / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D017384:Sequence Deletion; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D050257:Tubulin Modulators / Q000494:pharmacology; D014617:Vacuoles / Q000378:metabolism
chemical_list: C488173:Bik1 protein, S cerevisiae; D008869:Microtubule-Associated Proteins; C530135:Rtr1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D050257:Tubulin Modulators; D012319:RNA Polymerase II; C568359:Npa3 protein, S cerevisiae; D020559:Monomeric GTP-Binding Proteins; D001542:Benomyl
keywords: BIK1; Benomyl; GTPase Gpn1; Microtubules; Npa3/ScGpn1 carboxy terminal tail; Saccharomyces cerevisiae