ALTERED DNA RECOGNITION AND BENDING BY INSERTIONS IN THE ALPHA-2 TAIL OF THE YEAST A1/ALPHA-2 HOMEODOMAIN HETERODIMER

被引:20
作者
JIN, YS
MEAD, J
LI, T
WOLBERGER, C
VERSHON, AK
机构
[1] RUTGERS STATE UNIV, WAKSMAN INST, PISCATAWAY, NJ 08855 USA
[2] RUTGERS STATE UNIV, DEPT MOLEC BIOL & BIOCHEM, PISCATAWAY, NJ 08855 USA
[3] JOHNS HOPKINS UNIV, SCH MED, DEPT BIOPHYS & BIOPHYS CHEM, BALTIMORE, MD 21205 USA
[4] JOHNS HOPKINS UNIV, SCH MED, HOWARD HUGHES MED INST, BALTIMORE, MD 21205 USA
关键词
D O I
10.1126/science.270.5234.290
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
The yeast MAT alpha 2 and MATa1 homeodomain proteins bind cooperatively as a heterodimer to sites upstream of haploid-specific genes, repressing their transcription. In the crystal structure of alpha 2 and a1 bound to DNA, each homeodomain makes independent base-specific contacts with the DNA and the two proteins contact each other through an extended tail region of alpha 2 that tethers the two homeodomains to one another. Because this extended region may be flexible, the ability of the heterodimer to discriminate among DNA sites with altered spacing between alpha 2 and a1 binding sites was examined. Spacing between the half sites was critical for specific DNA binding and transcriptional repression by the complex. However, amino acid insertions in the tail region of alpha 2 suppressed the effect of altering an a1/alpha 2 site by increasing the spacing between the half sites. Insertions in the tail also decreased DNA bending by a1/alpha 2. Thus tethering the two homeodomains contributes to DNA bending by a1/alpha 2, but the precise nature of the resulting bend is not essential for repression.
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页码:290 / 293
页数:4
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