Kin2, the Budding Yeast Ortholog of Animal MARK/PAR-1 Kinases, Localizes to the Sites of Polarized Growth and May Regulate Septin Organization and the Cell Wall.
MARK/PAR-1 protein kinases play important roles in cell polarization in animals. Kin1 and Kin2 are a pair of MARK/PAR-1 orthologs in the budding yeast Saccharomyces cerevisiae. They participate in the regulation of secretion and ER stress response. However, neither the subcellular localization of these two kinases nor whether they may have other cellular functions is clear. Here, we show that Kin2 localizes to the sites of polarized growth in addition to localization on the plasma membrane. The localization to polarity sites is mediated by two targeting domains-TD1 and TD2. TD1 locates in the N-terminal region that spans the protein kinase domain whereas TD2 locates in the C-terminal end that covers the KA1 domain. We also show that an excess of Kin2 activity impaired growth, septin organization, and chitin deposition in the cell wall. Both TD1 and TD2 contribute to this function. Moreover, we find that the C-terminal region of Kin2 interacts with Cdc11, a septin subunit, and Pea2, a component of the polarisome that is known to play a role in septin organization. These findings suggest that Kin2 may play a role in the regulation of the septin cytoskeleton and the cell wall. Finally, we show that the C-terminal region of Kin2 interacts with Rho3, a Rho GTPase, whereas the N-terminal region of Kin2 interacts with Bmh1, a 14-3-3 protein. We speculate that Kin2 may be regulated by Bmh1, Rho3, or Pea2 in vivo. Our study provides new insight in the localization, function, and regulation of Kin2.
Department of Microbiology, College of Life Sciences, Wuhan University, Wuhan, China.
Si-Min
SM
Yuan
Department of Microbiology, College of Life Sciences, Wuhan University, Wuhan, China.
Wen-Chao
WC
Nie
Department of Microbiology, College of Life Sciences, Wuhan University, Wuhan, China.
Fei
F
He
Department of Microbiology, College of Life Sciences, Wuhan University, Wuhan, China.
Zhi-Wen
ZW
Jia
Department of Microbiology, College of Life Sciences, Wuhan University, Wuhan, China.|Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Wuhan, China.
Xiang-Dong
XD
Gao
D048948:14-3-3 Proteins / Q000378:metabolism; D002473:Cell Wall / Q000737:chemistry / Q000378:metabolism*; D008565:Membrane Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism*; D060066:Protein Interaction Maps; D017346:Protein Serine-Threonine Kinases / Q000032:analysis* / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism*; D058112:Septins / Q000032:analysis / Q000378:metabolism*; D015854:Up-Regulation; D020741:rho GTP-Binding Proteins / Q000378:metabolism
D048948:14-3-3 Proteins; C075852:BMH1 protein, S cerevisiae; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; C087572:KIN2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D058112:Septins; C074647:RHO3 protein, S cerevisiae; D020741:rho GTP-Binding Proteins