PINA is essential for growth and positively influences NIMA function in Aspergillus nidulans.
The phospho-Ser/Thr-directed prolyl-isomerase Pin1 was originally identified in vertebrate systems as a negative regulator of NIMA, a Ser/Thr protein kinase that regulates the G(2)/M transition in Aspergillus nidulans. Here we explore the physiological roles of the Pin1 orthologue, PINA, in A. nidulans and evaluate the relevance of the interaction of PINA with NIMA in this fungus. We find pinA to be an essential gene in A. nidulans. In addition, when PINA levels are reduced 50-fold the cells grow at a reduced rate. Upon germination under conditions that repress PINA expression, the cells are delayed in the interphase activation of NIMX(cdc2), whereas they traverse the other phases of the cell cycle at a similar rate to controls. These results indicate that a marked reduction of PINA results in a lengthening of G(1). Additionally, PINA repression increases the rate at which the cells enter mitosis following release from a hydroxyurea arrest without altering the sensitivity of the fungus to agents that activate the replication or DNA damage checkpoints. In contrast to predictions based on Pin1, the physical interaction between PINA and NIMA is primarily dependent upon the prolylisomerase domain of PINA and the C-terminal 303 amino acids of NIMA. Finally, reduction of PINA levels exacerbates the nimA5 temperature-sensitive mutant, whereas overexpression of PINA decreases the severity of this mutation, results that are consistent with a positive genetic interaction between PINA and NIMA. Thus, although PINA is essential and positively regulates NIMA function, A. nidulans is most sensitive to a reduction in PINA concentration in G(1) rather than in G(2)/M.
Joseph
James D
JD
Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Daigle
Scott N
SN
Means
Anthony R
AR
D000251:Adenosine Triphosphatases / Q000502:physiology*; D001233:Aspergillus nidulans / Q000201:enzymology*; D015153:Blotting, Western; D027682:Cation Transport Proteins / Q000502:physiology*; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000502:physiology*; D002455:Cell Division; D002467:Cell Nucleus / Q000378:metabolism; D000073840:Copper-Transporting ATPases; D016213:Cyclins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005656:Fungal Proteins / Q000378:metabolism; D016193:G1 Phase; D016195:G2 Phase; D015966:Gene Expression Regulation, Fungal; D005947:Glucose / Q000494:pharmacology; D005990:Glycerol / Q000494:pharmacology; D006918:Hydroxyurea / Q000494:pharmacology; D008938:Mitosis; D008957:Models, Genetic; D009154:Mutation; D000072380:NIMA-Related Kinase 1; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D017434:Protein Structure, Tertiary; D016196:S Phase; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D013696:Temperature; D013997:Time Factors; D020798:Two-Hybrid System Techniques; D014466:Ultraviolet Rays
D027682:Cation Transport Proteins; D018797:Cell Cycle Proteins; D016213:Cyclins; D005656:Fungal Proteins; C075058:NIME protein, Emericella nidulans; D000072380:NIMA-Related Kinase 1; D017346:Protein Serine-Threonine Kinases; D010744:Phosphoric Monoester Hydrolases; D000251:Adenosine Triphosphatases; D000073840:Copper-Transporting ATPases; D005947:Glucose; D005990:Glycerol; D006918:Hydroxyurea