title: A protein kinase screen of Neurospora crassa mutant strains reveals that the SNF1 protein kinase promotes glycogen synthase phosphorylation.
abstract: Glycogen functions as a carbohydrate reserve in a variety of organisms and its metabolism is highly regulated. The activities of glycogen synthase and glycogen phosphorylase, the rate-limiting enzymes of the synthesis and degradation processes, respectively, are regulated by allosteric modulation and reversible phosphorylation. To identify the protein kinases affecting glycogen metabolism in Neurospora crassa, we performed a screen of 84 serine/threonine kinase knockout strains. We identified multiple kinases that have already been described as controlling glycogen metabolism in different organisms, such as NcSNF1, NcPHO85, NcGSK3, NcPKA, PSK2 homologue and NcATG1. In addition, many hypothetical kinases have been implicated in the control of glycogen metabolism. Two kinases, NcIME-2 and NcNIMA, already functionally characterized but with no functions related to glycogen metabolism regulation, were also identified. Among the kinases identified, it is important to mention the role of NcSNF1. We showed in the present study that this kinase was implicated in glycogen synthase phosphorylation, as demonstrated by the higher levels of glycogen accumulated during growth, along with a higher glycogen synthase (GSN) ±glucose 6-phosphate activity ratio and a lesser set of phosphorylated GSN isoforms in strain Ncsnf1KO, when compared with the wild-type strain. The results led us to conclude that, in N. crassa, this kinase promotes phosphorylation of glycogen synthase either directly or indirectly, which is the opposite of what is described for Saccharomyces cerevisiae. The kinases also play a role in gene expression regulation, in that gdn, the gene encoding the debranching enzyme, was down-regulated by the proteins identified in the screen. Some kinases affected growth and development, suggesting a connection linking glycogen metabolism with cell growth and development.
authors.affiliation: *Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista (UNESP), 14800-900, Araraquara, SP, Brazil.
authors.forename: Thiago De Souza
authors.initials: Tde S
authors.lastname: Candido
authors.affiliation: *Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista (UNESP), 14800-900, Araraquara, SP, Brazil.
authors.forename: Rodrigo Duarte
authors.initials: RD
authors.lastname: Gonçalves
authors.affiliation: *Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista (UNESP), 14800-900, Araraquara, SP, Brazil.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Felício
authors.affiliation: *Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista (UNESP), 14800-900, Araraquara, SP, Brazil.
authors.forename: Fernanda Zanolli
authors.initials: FZ
authors.lastname: Freitas
authors.affiliation: *Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista (UNESP), 14800-900, Araraquara, SP, Brazil.
authors.forename: Fernanda Barbosa
authors.initials: FB
authors.lastname: Cupertino
authors.affiliation: *Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista (UNESP), 14800-900, Araraquara, SP, Brazil.
authors.forename: Ana Carolina Gomes Vieira
authors.initials: AC
authors.lastname: De Carvalho
authors.affiliation: *Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista (UNESP), 14800-900, Araraquara, SP, Brazil.
authors.forename: Maria Célia
authors.initials: MC
authors.lastname: Bertolini
mesh_terms: D015971:Gene Expression Regulation, Enzymologic; D006003:Glycogen / Q000096:biosynthesis; D006006:Glycogen Synthase / Q000378:metabolism*; D057166:High-Throughput Screening Assays; D009492:Neurospora crassa / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D030781:Organisms, Genetically Modified; D010766:Phosphorylation; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014199:Trehalose / Q000378:metabolism
chemical_list: D006003:Glycogen; D014199:Trehalose; D006006:Glycogen Synthase; D011494:Protein Kinases; C071570:SNF1-related protein kinases; D017346:Protein Serine-Threonine Kinases