ER-ミトコンドリアの結合複合体は,合成生物学スクリーンで明らかになりました
Benoît Kornmann1, Erin Currie, Sean R Collins
1Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, CA 94158, USA. benoit.kornmann@ucsf.edu
まとめ
研究者らは,タンパク質複合体 (Mmm1/Mdm10/Mdm12/Mdm34) を特定し,それは,エンドプラズマ網膜 (ER) とミトコンドリアを結びつける分子鎖として作用する. この発見は,臓器細胞の伝達と細胞機能におけるその役割に光を当てています.
科学分野:
- 細胞生物学 細胞生物学
- 分子生物学は分子生物学である.
- バイオケミストリー バイオケミストリー
背景:
- 臓器間のコミュニケーションは,真核細胞の機能にとって極めて重要です.
- ミトコンドリアとエンドプラズマ網膜 (ER) の相互作用は,細胞プロセスにとって不可欠です.
- ミトコンドリア-ER結合の分子メカニズムを理解することは,活発な研究分野です.
研究 の 目的:
- ミトコンドリアとERを結びつける分子成分を特定する.
- 細胞プロセスにおけるこれらの結合構成要素の機能的役割を調査する.
主な方法:
- 合成結合タンパク質で補完された変異体のスクリーニング.
- Mmm1/Mdm10/Mdm12/Mdm34タンパク質複合体を特定する.
- ゲノム全体の遺伝子相互作用のマッピング.
- テザリング複合体のローカライゼーション研究.
主要な成果:
- Mmm1/Mdm10/Mdm12/Mdm34複合体は,ERとミトコンドリアの間の分子結合として特定されました.
- この複合体は,両方の臓器細胞に存在するタンパク質で構成されています.
- 遺伝的相互作用は,この複合体を,リン脂生物合成とカルシウムシグナル伝達と結びつけました.
- 変異細胞は,フォスフォリピド生物合成の障害を示した.
- 複合体は,ER-ミトコンドリアの特定の位置を示す,離散的焦点に局所化しました.
結論:
- Mmm1/Mdm10/Mdm12/Mdm34複合体は,ERとミトコンドリアを物理的に結びつける.
- これらの特殊な結節は,カルシウムとリン脂の臓器間交換のための場所です.
- この発見は,オルゲネルの接触部位の調節と,その機能的影響についての洞察を提供します.
関連する概念動画
Mitochondrial Protein Sorting
Mitochondria are double-membrane organelles of the eukaryotes involved in cellular metabolism, signaling, ATP synthesis, and programmed cell death. Each of these processes requires specific proteins and enzymes that must be correctly sorted to the right mitochondrial subcompartment for the proper functioning of the organelle.
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
Translocation of Proteins into the Mitochondria
Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
The Inner Mitochondrial Membrane
The inner mitochondrial membrane is the primary site of ATP synthesis. The inner membrane domain that forms a smooth layer adjacent to the outer membrane is called the inner boundary membrane. This domain contains membrane transporters that drive metabolites in and out of the mitochondria. In contrast, the inner membrane network that invaginates into the matrix space is called the cristae membrane. This domain accounts for principle mitochondrial function as it accommodates the protein...
Porin Insertion in the Outer Mitochondrial Membrane
Porins are beta-barrel proteins translocated to the mitochondrial outer membrane through the TOM complex into the intermembrane space. Porin precursors bind TIM chaperones within the intermembrane space and are guided to the Sorting and Assembly Machinery complex or SAM complex on the outer mitochondrial membrane.
Three models describe the assembly of porins by the SAM complex and their insertion into the outer membrane. Model 1 suggests that porins are assembled outside the SAM channel as the...
Three models describe the assembly of porins by the SAM complex and their insertion into the outer membrane. Model 1 suggests that porins are assembled outside the SAM channel as the...
Protein Transport into the Inner Mitochondrial Membrane
Nuclear encoded mitochondrial precursors are imported to the inner membrane in a multistep process involving two separate translocons, TIM22 and TIM23. TIM23 is a cation-selective pore that remains closed by the N terminal segment of the protein. Negative charges on the TIM23 act as a receptor for the incoming precursor, pulling the positively charged matrix-targeting sequence for peptide insertion and translocation.
Transport of mitochondrial precursors across the TIM23 channel is driven by...
Transport of mitochondrial precursors across the TIM23 channel is driven by...
Mitochondrial Membranes
A single mitochondrion is a bean-shaped organelle enclosed by a double-membrane system. The outer membrane of mitochondria is smooth and contains many porins - the integral membrane transporters. Porins enable free diffusion of ions and small uncharged molecules through the outer mitochondrial membrane but limit the transport of molecules larger than 5000 Daltons. Further, the outer mitochondrial membrane forms a unique structure called membrane contact sites with other subcellular organelles,...


