Termination-altering amino acid substitutions in the beta' subunit of Escherichia coli RNA polymerase identify regions involved in RNA chain elongation.
Termination-altering amino acid substitutions in the beta' subunit of Escherichia coli RNA polymerase identify regions involved in RNA chain elongation.
复制标题
大肠杆菌 RNA 聚合酶 β 亚基中终止改变的氨基酸取代可识别参与 RNA 链延长的区域。
DOI：
10.1101/gad.8.23.2913
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发表时间：
1994
影响因子：
10.5
通讯作者：
Landick,R
中科院分区：
文献类型：
--
作者：
Weilbaecher,R;Hebron,C;Feng,G;Landick,R
为了确定可能参与转录延长和终止的RNA聚合酶最大亚基的区域，我们已经表征了大肠杆菌RNA聚合酶β '亚基中的氨基酸取代，其改变了体内终止子之前的报告基因的表达。终止改变取代发生在β '的离散片段中，命名为2、3a、3b、4a、4 b、4c和5，其中许多在β'的真核同源物中高度保守。区域2的取代（残基311-386）紧密地聚集在一个短序列周围，该短序列类似于E. coli DNA聚合酶I。区域3b（残基718-798）对应于RNA聚合酶II的最大亚基的区段，其中发生鹅膏蕈碱抗性取代。区域4a取代（残基933-936）发生在被认为接触转录物3'端的区段中。区域5取代（残基1308-1356）紧密聚集在靠近β '的羧基末端的保守区域H中。一组代表性的突变体RNA聚合酶进行纯化，并揭示了在六个不同的rho-非依赖性终止子的终止百分比的意外变化。基于这些取代的位置和性质，我们提出了一个假设的转录复合体中的亚基的关系。
To identify regions of the largest subunit of RNA polymerase that are potentially involved in transcript elongation and termination, we have characterized amino acid substitutions in the beta' subunit of Escherichia coli RNA polymerase that alter expression of reporter genes preceded by terminators in vivo. Termination-altering substitutions occurred in discrete segments of beta', designated 2, 3a, 3b, 4a, 4b, 4c, and 5, many of which are highly conserved in eukaryotic homologs of beta'. Region 2 substitutions (residues 311-386) are tightly clustered around a short sequence that is similar to a portion of the DNA-binding cleft in E. coli DNA polymerase I. Region 3b (residues 718-798) corresponds to the segment of the largest subunit of RNA polymerase II in which amanitin-resistance substitutions occur. Region 4a substitutions (residues 933-936) occur in a segment thought to contact the transcript 3' end. Region 5 substitutions (residues 1308-1356) are tightly clustered in conserved region H near the carboxyl terminus of beta'. A representative set of mutant RNA polymerases were purified and revealed unexpected variation in percent termination at six different rho-independent terminators. Based on the location and properties of these substitutions, we suggest a hypothesis for the relationship of subunits in the transcription complex.