Yeast Nap1-binding protein Nbp2p is required for mitotic growth at high temperatures and for cell wall integrity.
Nbp2p is a Nap1-binding protein in Saccharomyces cerevisiae identified by its interaction with Nap1 by a two-hybrid system. NBP2 encodes a novel protein consisting of 236 amino acids with a Src homology 3 (SH3) domain. We showed that NBP2 functions to promote mitotic cell growth at high temperatures and cell wall integrity. Loss of Nbp2 results in cell death at high temperatures and in sensitivity to calcofluor white. Cell death at high temperature is thought not to be due to a weakened cell wall. Additionally, we have isolated several type-2C serine threonine protein phosphatases (PTCs) as multicopy suppressors and MAP kinase-kinase (MAPKK), related to the yeast PKC MAPK pathway, as deletion suppressors of the nbp2Delta mutant. Screening for deletion suppressors is a new genetic approach to identify and characterize additional proteins in the Nbp2-dependent pathway. Genetic analyses suggested that Ptc1, which interacts with Nbp2 by the two-hybrid system, acts downstream of Nbp2 and that cells lacking the function of Nbp2 prefer to lose Mkk1, but the PKC MAPK pathway itself is indispensable when Nbp2 is deleted at high temperature.
Laboratory of Medical Mycology, Research Institute for Disease Mechanism and Control, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.
Kentaro
K
Ohkuni
Asuko
A
Okuda
Akihiko
A
Kikuchi
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002473:Cell Wall / Q000378:metabolism*; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism; D008938:Mitosis / Q000502:physiology*; D009154:Mutation; D009687:Nuclear Proteins; D056490:Nucleosome Assembly Protein 1; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013696:Temperature
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C533556:NAP1 protein, S cerevisiae; C487575:NBP2 protein, S cerevisiae; D009687:Nuclear Proteins; D056490:Nucleosome Assembly Protein 1; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; D011505:Protein-Tyrosine Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D020929:Mitogen-Activated Protein Kinase Kinases