EVIDENCE FOR A CONTACT BETWEEN GLUTAMINE-18 OF LAC REPRESSOR AND BASE PAIR-7 OF LAC OPERATOR
EVIDENCE FOR A CONTACT BETWEEN GLUTAMINE-18 OF LAC REPRESSOR AND BASE PAIR-7 OF LAC OPERATOR
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DOI：
10.1073/pnas.83.2.303
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发表时间：
1986-01-01
影响因子：
11.1
通讯作者：
EBRIGHT, RH
中科院分区：
文献类型：
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作者：
EBRIGHT, RH
乳胶抑制物(LACR)的谷氨酰胺-18已被甘氨酸、丝氨酸和亮氨酸所取代。针对lac操纵子(LACO)的5、6、7、8、9和10碱基对，分析了野生型LACR和三个替代LACR变体的特异性。这些数据表明，[Gly18]LACR、[Ser18]LACR、[Leu18]LACR失去了区分O+碱基对G.cntpoint的能力。C和Oc碱基对T.cntdo.A和A.cntdot。T在LACO的位置7(KDOC/KdO+.simeq.1)。相反，三个被取代的变异体保留了在彼此位置区分O+和Oc的能力，其倍数为9到37。因此，我认为谷氨酰胺-18与LACO的7个碱基对接触。这些数据表明，在LACR和分解代谢基因激活蛋白中，螺旋-转角-螺旋基序与DNA的相互作用可能非常相似或相同。
Glutamine-18 of the lac repressor (lacR) has been substituted by glycine, by serine, and by leucine. The specificities of wild-type lacR and of the three substituted lacR variants have been analyzed with respect to base pairs 5, 6, 7, 8, 9, and 10 of the lac operator (lacO). The data indicate that [Gly18]lacR, [Ser18]lacR, [Leu18]lacR lose the ability to distinguish between the O+ base pair G .cntdot. C and the Oc base pairs T .cntdot. A and A .cntdot. T at position 7 of lacO (KdOc/KdO+ .simeq. 1). In contrast, the three substituted variants retain the ability to discriminate O+ from Oc at each other position, by factors of 9 to 37. Therefore, I propose that glutamine-18 contacts base pair 7 of lacO. These data suggest that the interaction between the helix-turn-helix motif and DNA may be very similar or identical in lacR and the catabolite gene activator protein.