Tn7トランスポーゼーション:標的DNAの認識は,精製されたインビトロシステムで,複数のTn7エンコードタンパク質によって媒介されます
R J Bainton1, K M Kubo, J N Feng
1Department of Biochemistry and Biophysics, George W. Hooper Foundation, University of California, San Francisco 94143.
Cell
|March 26, 1993
まとめ
研究者らは,4つのタンパク質 (TnsA,TnsB,TnsC,TnsD) とATPを用いて,細菌のトランポソンTn7のトランポジションを再構成した. この研究は,Tn7が特定のDNA部位に挿入されるメカニズムを明らかにしています.
科学分野:
- 分子生物学は分子生物学である.
- 遺伝学 遺伝学とは
- バイオケミストリー バイオケミストリー
背景:
- 細菌のトランポゾンTn7のようなトランポザブル要素は,移動性DNA配列である.
- 転置メカニズムを理解することは,遺伝子調節とゲノム安定性にとって極めて重要です.
研究 の 目的:
- バクテリアのトランポゾンTn7の特定の挿入部位への転置を再構成および分析するには,attTn7.
- 転置プロセスにおける個々のTn7エンコードタンパク質 (TnsA,TnsB,TnsC,TnsD) の役割を解明する.
主な方法:
- 純化されたTnsA,TnsB,TnsC,TnsDタンパク質とATPを用いてTn7トランスポーゼーションのIn vitro再構成.
- Tnsタンパク質によって媒介されるDNA破裂と結合活動の分析.
- タンパク質とDNAの相互作用の調査,特に再結合機構をattTn7サイトにターゲットにする.
主要な成果:
- Tn7のトランスポジションをTnsA+TnsB+TnsC+TnsDとATPで成功裏に再構成した.
- TnsA+TnsB+TnsCは,トランポゾン末端を認識する核再結合複合体を形成する.
- TnsDはattTn7のターゲットサイトを特定して,TnsC経由でコアコンプレクスを指向します.
- 再結合は,核タンパク質複合体の組み立てによって活性化されます.
- TnsCは,トランポゾンと標的DNAの間の通信に中心的な役割を果たし,潜在的に再挿入を防ぐ可能性があります.
結論:
- この研究は,Tn7転移の詳細なメカニズム的理解を提供します.
- Tn7のトランスポーゼーションは,特定のタンパク質-DNA相互作用と複雑なアセンブリを含む高度に規制されたプロセスです.
- この発見は,ターゲットサイトの選択とトランスポーゼーションの規制におけるTnsCの役割を強調しています.
関連する概念動画
Translesion DNA Polymerases
Translesion (TLS) polymerases rescue stalled DNA polymerases at sites of damaged bases by replacing the replicative polymerase and installing a nucleotide across the damaged site. Doing so, TLS allows additional time for the cell to repair the damage before resuming regular DNA replication.
TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...
TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...
Overview of Transposition and Recombination
Transposons make up a significant part of genomes of various organisms. Therefore, it is believed that transposition played a major evolutionary role in speciation by changing genome sizes and modifying gene expression patterns. For example, in bacteria, transposition can lead to conferring antibiotic resistance. Movement of transposable elements within the genetic pool of pathogenic bacteria can aid in transfer of antibiotic-resistant genetic elements. In eukaryotes, transposons can carry out...
DNA-only Transposons
DNA-only transposons are called autonomous transposons since they code for the enzyme transposase that is required for the transposition mechanism. Insertion of transposons can alter gene functions in multiple ways. They can mutate the gene, alter gene expression by introducing a novel promoter or insulator sequence, introduce new splice sites, and change the mRNA transcripts produced, or remodel chromatin structure.
The donor site from where the transposon is excised is either degraded or...
The donor site from where the transposon is excised is either degraded or...
Transfer RNA Synthesis
One of the unique features of tRNA is the presence of modified bases. In some tRNAs, modified bases account for nearly 20% of the total bases in the molecule. Altogether, these unusual bases protect the tRNA from enzymatic degradation by RNases.
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
tRNA Activation
Aminoacyl-tRNA synthetases are present in both eukaryotes and bacteria. Though eukaryotes have 20 different aminoacyl-tRNA synthetases to couple to 20 amino acids, many bacteria do not have genes for all of these aminoacyl-tRNA synthetases. Despite this, they still use all 20 amino acids to synthesize their proteins. For instance, some bacteria do not have the gene encoding the enzyme that couples glutamine with its partner tRNA. In these organisms, one enzyme adds glutamic acid to all of the...
Nonsense-mediated mRNA Decay
The Upf proteins that carry out nonsense-mediated decay (NMD) are found in all eukaryotic organisms, including humans. Each protein has an individual role, but they need to work in collaboration. Upf1 is an ATP-dependent RNA helicase that unwinds the RNA helix. Because Upf1 can unwind any RNA, Upf2 and Upf3 are required to help Upf1 discriminate between nonsense and normal mRNAs.
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...


