The Arabidopsis Athb-8, -9 and genes are members of a small gene family coding for highly related HD-ZIP proteins |
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Authors: | Sessa Giovanna Steindler Corinna Morelli Giorgio Ruberti Ida |
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Institution: | (1) Centro di studio per gli Acidi Nucleici, c/o Dipartimento di Genetica e Biologia Molecolare, Università di Roma La Sapienza, P.le Aldo Moro 5, 00185 Rome, Italy.;(2) Unità di Nutrizione Sperimentale, Istituto Nazionale della Nutrizione, Via Ardeatina 546, 00178 Rome, Italy; |
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Abstract: | We report the isolation and characterization of two Arabidopsis homeobox genes highly related to the Athb-8 gene. The full-length cDNAs encode proteins of 841 and 852 amino acids which we have designated Athb-9 and -14, respectively. Athb-8, -9 and -14 are members of a small family of HD-Zip proteins (HD-ZIP III) characterized by a HD-Zip motif confined to the N-terminus of the polypeptide. The spatial organization of the HD-Zip domain of Athb-8, -9 and -14 is different from that of the Athb-1 (a member of the HD-ZIP I family) and Athb-2 (a member of the HD-ZIP II family) HD-Zip domains. DNA binding analysis performed with random-sequence DNA templates showed that the Athb-9 HD-Zip (HD-Zip-9) domain, but not the Athb-9 HD alone, binds to DNA. The HD-Zip-9 domain recognizes a 11 bp pseudopalindromic sequence (GTAAT(G/C)ATTAC), as determined by selecting high-affinity binding sites from random-sequence DNA. Moreover, gel retardation assays demonstrated that the HD-Zip-9 domain binds to DNA as a dimer. These data support the notion that the HD-ZIP III domain interacts with DNA recognition elements in a fashion similar to the HD-ZIP I and II domains. |
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Keywords: | binding site selection gene expression homeobox-leucine zipper genes protein-DNA interaction |
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