Nuclear factor-Y (NF-Y) is a class of transcription factor that plays decisive roles in diverse developmental pathways in plants and other eukaryotes. These are also present in other eukaryotes as known as CCAAT-binding factor (CBF) or heme activator protein (HAP).  NF-Y specifically recognizes the regulatory CCAAT element found in either orientation in the proximal and distal enhancer regions of many genes. In higher eukaryotes, this element is found in about 30% of the promoters, preferentially in the −60/−100 region. The CCAAT box acts in concert with neighboring elements, and its bending by NF-Y is thought to be a major mechanism required for transcription activation.

NF-Y is a heterotrimeric complex composed of NF-YA (CBF-B,HAP2), NF-YB (CBF-A, HAP3), and NF-YC (CBF-C, HAP5). Each subunit contains a core region (defined by pFAM00808) that has been highly conserved throughout evolution and that is sufficient for subunit interactions and CCAAT binding, whereas the flanking regions, which include the activation domains, are much less conserved.  The NF-YA subunit is further defined by the pFAM02045 motif. The NF-YB subunit is further sub-grouped into LEC (Leafy cotyledon) and non-LEC categories. NF-YC and NF-YB core regions are homologous in sequence to histones H2A and H2B, respectively, and are required for heterodimerization, a prerequisite for NF-YA association and CCAAT binding

The presence of multiple forms of each HAP homolog in Arabidopsis compared with the single genes in yeast and vertebrates suggests that the HAP2/3/5 complex may play diverse roles in gene transcription in higher plants. In maize, there are 50 ZmNF-Y (14 ZmNF-YA (HAP2), 18 ZmNF-YB (HAP3), and 18 ZmNF-YC (HAP5)) genes as determined by analysis of the entire genome (Zhang et al. 2016, PMID: 27498027). Microarray data showed that the ZmNF-Y genes had tissue-specific expression patterns in various maize developmental stages and in response to biotic and abiotic stresses. The results suggested that ZmNF-YB2, 4, 8, 10, 13, and 16 and ZmNF-YC6, 8, and 15 were induced, while ZmNF-YA1, 3, 4, 6, 7, 10, 12, and 13, ZmNF-YB15, and ZmNF-YC3 and 9 were suppressed by drought stress. ZmNF-YA3, ZmNF-YA8 and ZmNF-YA12 were upregulated after infection by the three pathogens, while ZmNF-YA1 and ZmNF-YB2 were suppressed. These results indicate that the ZmNF-Ys may have significant roles in the response to abiotic and biotic stresses  (Zhang et al. 2016, Zhang et al., 2023).

Last updated June 2023 by John Gray

References:

Zhang Z, Li X, Zhang C, Zou H, Wu Z. Isolation, structural analysis, and expression characteristics of the maize nuclear factor Y gene families. Biochem Biophys Res Commun. 2016 Sep 16;478(2):752-8. doi: 10.1016/j.bbrc.2016.08.020. Epub 2016 Aug 4. PMID: 27498027. 

Yang Y, Wang B, Wang J, He C, Zhang D, Li P, Zhang J, Li Z. Transcription factors ZmNF-YA1 and ZmNF-YB16 regulate plant growth and drought tolerance in maize. Plant Physiol. 2022 Sep 28;190(2):1506-1525. doi: 10.1093/plphys/kiac340. PMID: 35861438; PMCID: PMC9516732.

Zhang H, Liu S, Ren T, Niu M, Liu X, Liu C, Wang H, Yin W, Xia X. Crucial Abiotic Stress Regulatory Network of NF-Y Transcription Factor in Plants. Int J Mol Sci. 2023 Feb 23;24(5):4426. doi: 10.3390/ijms24054426. PMID: 36901852; PMCID: PMC10002336.