Xing Y, Fikes J D, Guarente L
Department of Biology, MIT, Cambridge, MA 02139.
EMBO J. 1993 Dec;12(12):4647-55. doi: 10.1002/j.1460-2075.1993.tb06153.x.
We describe a detailed genetic analysis of the DNA-binding regions in the HAP2/HAP3 CCAAT-binding heteromeric complex. The DNA-binding domain of HAP2 is shown to be a 21 residue region containing three critical histidines and three critical arginines. Mutation of an arginine at position 199 to leucine alters the DNA-binding specificity of the complex to favor CCAAC over CCAAT. Residues in HAP3 that are critical for DNA-binding comprise a short, seven amino acid region. Three different mutations in the HAP2 DNA-binding domain are suppressed by a mutation in the HAP3 DNA-binding domain. This HAP3 mutation also suppresses mutations in a different region of HAP2 which promotes subunit assembly of the complex. These findings suggest that short regions of HAP2 and HAP3 comprise a hybrid DNA-binding domain and that this domain can help hold the two subunits together in the CCAAT-binding complex.
我们描述了对HAP2/HAP3 CCAAT结合异源复合物中DNA结合区域的详细遗传分析。结果显示，HAP2的DNA结合结构域是一个包含三个关键组氨酸和三个关键精氨酸的21个残基区域。将第199位的精氨酸突变为亮氨酸会改变复合物的DNA结合特异性，使其更倾向于结合CCAAC而非CCAAT。HAP3中对DNA结合至关重要的残基组成了一个短的、由七个氨基酸组成的区域。HAP2 DNA结合结构域中的三种不同突变被HAP3 DNA结合结构域中的一种突变所抑制。这种HAP3突变还抑制了HAP2不同区域中促进复合物亚基组装的突变。这些发现表明，HAP2和HAP3的短区域组成了一个混合DNA结合结构域，并且该结构域有助于在CCAAT结合复合物中将两个亚基结合在一起。
