Two NDR kinase-MOB complexes function as distinct modules during septum formation and tip extension in Neurospora crassa.
NDR kinases are important for growth and differentiation and require interaction with MOB proteins for activity and function. We characterized the NDR kinases and MOB activators in Neurospora crassa and identified two NDR kinases (COT1 and DBF2) and four MOB proteins (MOB1, MOB2A, MOB2B and MOB3/phocein) that form two functional NDR-MOB protein complexes. The MOB1-DBF2 complex is not only essential for septum formation in vegetative cells and during conidiation, but also functions during sexual fruiting body development and ascosporogenesis. The two MOB2-type proteins interact with both COT1 isoforms and control polar tip extension and branching by regulating COT1 activity. The conserved region directly preceding the kinase domain of COT1 is sufficient for the formation of COT1-MOB2 heterodimers, but also for kinase homodimerization. An additional N-terminal extension that is poorly conserved, but present in most fungal NDR kinases, is required for further stabilization of both types of interactions and for stimulating COT1 activity. COT1 lacking this region is degraded in a mob-2 background. We propose a specific role of MOB3/phocein during vegetative cell fusion, fruiting body development and ascosporogenesis that is unrelated to the three other MOB proteins and NDR kinase signalling.
Institut für Mikrobiologie und Genetik, Abteilung Molekulare Mikrobiologie, Universität Gottingen Grisebachstr. 8, D-37077 Göttingen, Germany.
Sabine
S
Maerz
Anne
A
Dettmann
Carmit
C
Ziv
Yi
Y
Liu
Oliver
O
Valerius
Oded
O
Yarden
Stephan
S
Seiler
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D016764:Cell Polarity / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D005816:Genetic Complementation Test; D020409:Molecular Motor Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009492:Neurospora crassa / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D011485:Protein Binding / Q000235:genetics; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000235:genetics; D021381:Protein Transport / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction / Q000235:genetics
D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D020409:Molecular Motor Proteins; D029701:Saccharomyces cerevisiae Proteins; D017346:Protein Serine-Threonine Kinases