title: Calcium-Dependent Protein Kinase in Ginger Binds with Importin-α through Its Junction Domain for Nuclear Localization, and Further Interacts with NAC Transcription Factor.
abstract: Calcium-dependent protein kinases (CDPKs) are important sensors of Ca2+elevations in plant cells regulating the gene expression linked with various cellular processes like stress response, growth and development, metabolism, and cytoskeleton dynamics. Ginger is an extensively used spice due to its unique flavor and immense medicinal value. The two major threats that interfere with the large scale production of ginger are the salinity and drought stress. ZoCDPK1 (Zingiber officinaleCalcium-dependent protein kinase 1) is a salinity and drought-inducible CDPK gene isolated from ginger and undergoes dynamic subcellular localization during stress conditions. ZoCDPK1, with signature features of a typical Ca2+regulated kinase, also possesses a bipartite nuclear localization sequence (NLS) in its junction domain (JD). A striking feature in ZoCDPK1 is the rare occurrence of a coupling between the NLS in JD and consensus sequences in regulatory domain. Here, we further identified its nature of nuclear localization and its interaction partners. In the homology model generated for ZoCDPK1, the regulatory domain mimics the crystal structure of the regulatory domain inArabidopsisCDPK1. Molecular docking simulation of importin (ZoIMPα), an important protein involved in nuclear translocation, into the NLS of ZoCDPK1 was well-visualized. Furthermore, the direct interaction of ZoCDPK1 and ZoIMPα proteins was studied by the yeast 2-hybrid (Y2H) system, which confirmed that junction domain (JD) is an important interaction module required for ZoCDPK1 and ZoIMPα binding. The probable interacting partners of ZoCDPK1 were also identified using Y2H experiment. Of the 10 different stress-related interacting partners identified for ZoCDPK1, NAC transcription factor (TF) needs special mention, especially in the context of ZoCDPK1 function. The interaction between ZoCDPK1 and NAC TF, in fact, corroborate with the results of gene expression and over-expression studies of ZoCDPK1. Hence ZoCDPK1 is operating through NAC TF mediated ABA-independent, cold non-responsive stress signaling pathway in ginger.
authors.affiliation: Rajiv Gandhi Centre for Biotechnology Thiruvananthapuram, India.
authors.forename: Padmanabhan Jayanthi
authors.initials: PJ
authors.lastname: Vivek
authors.affiliation: Rajiv Gandhi Centre for Biotechnology Thiruvananthapuram, India.
authors.forename: Mohankumar Saraladevi
authors.initials: MS
authors.lastname: Resmi
authors.affiliation: Rajiv Gandhi Centre for Biotechnology Thiruvananthapuram, India.
authors.forename: Sweda
authors.initials: S
authors.lastname: Sreekumar
authors.affiliation: Rajiv Gandhi Centre for Biotechnology Thiruvananthapuram, India.
authors.forename: K C
authors.initials: KC
authors.lastname: Sivakumar
authors.affiliation: Amity Institute of Microbial Technology, Amity University Noida, India.
authors.forename: Narendra
authors.initials: N
authors.lastname: Tuteja
authors.affiliation: Rajiv Gandhi Centre for Biotechnology Thiruvananthapuram, India.
authors.forename: Eppurathu Vasudevan
authors.initials: EV
authors.lastname: Soniya
keywords: calcium-dependent protein kinase; ginger; importin; nuclear localization sequence; transcription factor