A mutation within the catalytic domain of COT1 kinase confers changes in the presence of two COT1 isoforms and in Ser/Thr protein kinase and phosphatase activities in Neurospora crassa

Rena Gorovits, Oshrat Propheta, Mikhail Kolot, Viktor Dombradi, Oded Yarden*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Neurospora crassa grows by forming spreading colonies. cot-1 belongs to a class of N. crassa colonial temperature-sensitive (cot) mutants and encodes a Ser/Thr protein kinase. We have mapped the cot-1 mutation to a single base change resulting in a His to Arg substitution at amino acid 351, which resides within the catalytic domain. Antibodies raised against COT1 detected and immunoprecipitated a predominant 73-kDa polypeptide in N. crassa extracts, whose abundance was constant under all growth conditions tested. An additional, lower MW COT1 isoform (67-kDa) present in the wild-type was not detected in cot-1 grown at the restrictive temperature. Similarly, this isoform was not detected in cot-3 or cot-5 strains, when grown at restrictive temperatures. Reduced levels of Ser/Thr kinase activity and an increase in type 1 and type 2B phosphatase (calcineurin) activities were measured in a cot-1 background. Apparent changes in the phosphorylation state of the p150(Glued) subunit of the dynactin cytoskeletal motor component (encoded by ro-3, a suppressor of cot-1) and evidence of in vitro physical interactions between COT1 and calcineurin indicate a functional linkage among COT1 kinase, type 2B phosphatase, and dynactin.

Original languageAmerican English
Pages (from-to)264-274
Number of pages11
JournalFungal Genetics and Biology
Volume27
Issue number2-3
DOIs
StatePublished - Jul 1999

Bibliographical note

Funding Information:
We thank Drs. Michael Plamann for providing anti-RO1 and anti-RO3 antibodies, Holger Prokisch for anti PP2B antibodies, Kornelia Szucs for assistance in performing PP2B activity assays, and Mrs. Margit Biro for technical assistance. The authors thank Dr. Michael Plamann for his comments on the manuscript. This research was supported by BARD, The United States Israel Binational Agricultural Research and Development Fund, The Israel Academy of Sciences and Humanities, and by a bilateral Israeli–Hungarian scientist exchange program. V.D. was supported by the Hungarian Research Council (OTKA 22675).

Keywords

  • COT1 kinase
  • Calcineurin
  • Dynactin
  • Fungal growth and development
  • Neurospora crassa

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