CAAT box

The CAAT box signals the binding site for the RNA transcription factor, and is typically accompanied by a conserved consensus sequence.

It is an invariant DNA sequence at about minus 70 base pairs from the origin of transcription in many eukaryotic promoters.

Full gene expression occurs when transcription activator proteins bind to each module within the regulatory promoter.

[2] In the direction of transcription of the template strand, the consensus sequence, or the calculated order of the most frequent residues, for the CAAT box was 3'-TG ATTGG (T/C)(T/C)(A/G)-5'.

[3] In another experiment performed with the major late promoter (MLP) of adenoviruses from a variety of host species, it was shown that the mutation of the CAAT box and CCAAT sequence, which is thought to play a pivotal role in the (MLP) of subgroup C human adenoviruses, in species with a deficient CAAT sequence.

[6] The NF-YA family encodes transcription factors that are variable in length (between 207 and 347 amino acids for M. truncatula).

The NF-YA proteins are generally characterized by two domains that are strongly conserved in all higher eukaryotes investigated to date.

The first domain (A1) contains 20 amino acids that forms an alpha helix that appears significant in its interactions with NF-YB and NF-YC.

Similar to NF-YA, NF-YB has been shown to also improve drought resistance when overexpressed and also the promotion of flowering in Arabidopsis.

[10] Because of the evolutionary change in NF-Y encoding genes in plants, they subsequently have a large range of potential trimeric complexes.

Functional analyses on NF-Y encoding genes in plants have shown, as a result of their evolutionary diversification relative to their animal counterparts, have acquired diverse specific functions, such as embryo development, flowering time control, ER-stress, drought stress, and nodule and root development.

They are a group of transcription factors of 6 members (α-ζ), which are highly conserved and bind to the CCAAT motif.

[12] The C/EBPs follow a general basic-leucine zipper (bZIP) domain at the C-terminus and are able to form dimers with other C/EBPs or other transcription factors.

The left model is of the complex of NF-YC/NF-YB with the CCAAT element from the pro- 2(I) collagen promoter. The DNA backbone is shown as ribbons (purple) with the bases displayed. The two possible locations of the CCAAT box, according to the modeling, have been colored cyan. For the right model of the NF-Y/CCAAT complex. NF-YC, NF-YB and DNA are colored as in figure on the left, whereas NF-YA is colored blue. The two alternative positions for the linker connecting NF-YA1 and NF-YA2 sub-domains are shown as blue dotted lines. Secondary structure elements of the histone pair that are implicated in NF-YA1 and NF-YA2 recognition (see text) are labeled and colored in red and gray, respectively. For clarity, only the bases for the CCAAT pentanucleotide are shown and labeled. [ 1 ]