Regulation of the CCAAT-binding NF-Y subunits in Arabidopsis thaliana

NF-Y is a CCAAT-specific binding factor composed of three distinct subunits . In vertebrates and fungi all three subunits are encoded by evolutionary c onserved single copy genes. In this report we have cloned twenty-three NF-Y genes in A. thaliana, assessed their mRNA expression levels in a large num ber of tissues and confirmed that indeed multiple CCAAT-binding activities are present. Alignments of the genes coding for the three NF-Y subunits yie ld a considerable amount of information concerning the divergence/conservat ion of protein subdomains and of single residues within the conserved parts . Careful evaluation of mRNA expression levels by sensitive RT-PCR assays p rovide evidence that all three subunits have members that are ubiquitous an d others that are tissue-specific and induced only after the switch to repr oductive growth phase, in flowers and siliques. (C) 2001 Elsevier Science B .V. All rights reserved.