title: Interaction of NtCDPK1 calcium-dependent protein kinase with NtRpn3 regulatory subunit of the 26S proteasome in Nicotiana tabacum.
abstract: Using a yeast two-hybrid system, we identified NtRpn3, a regulatory subunit of 26S proteasome, as an interacting protein of NtCDPK1 calcium-dependent protein kinase in Nicotiana tabacum. Rpn3 in yeast is an essential protein involved in proteolysis of cell cycle regulatory proteins, and the carrot homolog of Rpn3 was previously isolated as a nuclear antigen that is mainly expressed in the meristem. NtCDPK1 physically interacts with NtRpn3 in vitro in a Ca2+-independent manner and phosphorylates NtRpn3 in a Ca2+-dependent manner with Mg2+ as a cofactor. NtCDPK1 and NtRpn3 are co-localized in the nucleus, nuclear periphery, and around plasma membrane in vivo. Both NtCDPK1 and AtRpn3, an NtRpn3 homolog of Arabidopsis, are mainly expressed in the rapidly proliferating tissues including shoot and root meristems, and developing floral buds. Virus-induced gene silencing of either NtRpn3 or NtCDPK1 resulted in the phenotypes of abnormal cell morphology and premature cell death in newly emerged leaves. Finally, NtCDPK1 interacts with NtRpn3 in vivo as shown by co-immunoprecipitation. Based on these results, we propose that NtCDPK1 and NtRpn3 are interacting in a common signal transduction pathway possibly for regulation of cell division, differentiation, and cell death in tobacco.
authors.affiliation: Laboratory of Plant Genomics, Korea Research Institute of Bioscience and Biotechnology, PO Box 115, Yusong, Taejon 305-600, Korea.
authors.forename: Sang Sook
authors.initials: SS
authors.lastname: Lee
authors.forename: Hye Sun
authors.initials: HS
authors.lastname: Cho
authors.forename: Gyeong Mee
authors.initials: GM
authors.lastname: Yoon
authors.forename: Joon-Woo
authors.initials: JW
authors.lastname: Ahn
authors.forename: Hyong-Ha
authors.initials: HH
authors.lastname: Kim
authors.forename: Hyun-Sook
authors.initials: HS
authors.lastname: Pai
mesh_terms: D002118:Calcium / Q000494:pharmacology; D002453:Cell Cycle; D016923:Cell Death; D002455:Cell Division; D048429:Cell Size; D008345:Manganese / Q000494:pharmacology; D010447:Peptide Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D018517:Plant Roots / Q000166:cytology / Q000378:metabolism; D018520:Plant Shoots / Q000166:cytology / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014026:Nicotiana / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases
chemical_list: D002118:Calcium; D008345:Manganese; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; D011494:Protein Kinases; D021122:Protein Subunits; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C061553:ATP dependent 26S protease