Molecular characterization of maize bHLH transcription factor (ZmKS), a new ZmOST1 kinase substrate

• Published in: Plant science (Limerick) 2016-12, Vol.253, p.1-12
• Main Authors: Rabissi, Agnese, Vilela, Belmiro, Lumbreras, Victoria, Ludevid, Dolors, Culiáñez-Macià, Francisco A., Pagés, Montserrat
• Format: Article
• Language: English
• Subjects: ABA-repressed; Abiotic stress; Abscisic Acid - metabolism; Amino Acid Sequence; Arabidopsis; Basic Helix-Loop-Helix Transcription Factors - chemistry; Basic Helix-Loop-Helix Transcription Factors - genetics; Basic Helix-Loop-Helix Transcription Factors - metabolism; bHLH transcription factor; Gene Expression; Molecular Sequence Data; Plant Proteins - chemistry; Plant Proteins - genetics; Plant Proteins - metabolism; Plants, Genetically Modified; Stomatal activity; Zea mays; Zea mays - chemistry; Zea mays - enzymology; Zea mays - genetics
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2016.09.003

•A maize ZmOST1 Kinase Substrate ZmKS, showing homology with basic helix-loop-helix (bHLH) DNA-binding transcription factor was identified.•ZmKS is an ABA-repressed trans-acting activator.•The ZmKS physiological function appears to be related to stomatal regulation, possibly maintaining the homeostatic balance of K+ in guard cell. In order to identify potential substrates of the maize kinase in the ABA signalling network, ZmOST1 was used as bait against a library of cDNAs from dehydrated young leaves. A ZmOST1-interactive polypeptide ZmKS (gene locus tag: GRMZM2G114873), showing homology with the Arabidopsis thaliana basic helix-loop-helix (bHLH) DNA-binding transcription factor was identified. Using a comparative genomic approach, the ZmKS corresponding protein was identified as conceptual translated bHLH transcription factor ABA-responsive kinase substrate. ZmKS is localized in the nucleus, shows a potential binding specificity preferentially detectable on cis-acting E-box like heptameric motifs CCACTTG and CAAGTTG, and is phosphorylated by maize protein kinase ZmOST1. ZmKS is expressed in embryo, leaf and root, expression being affected by ABA and osmotic stress. Transgenic Arabidopsis plants, with gain of ZmKS function, show a delay in germination and a transcriptional stomatal opening-facilitator activity, switchover upon ZmKS phosphorylation, suggesting that ZmKS is an ABA-repressed trans-acting activator.