光合成膜タンパク質におけるアスパルチルアルデヒドという翻訳後の改変の証拠
Lorraine B Anderson1, Anthony J A Ouellette, Julian Eaton-Rye
1Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, St. Paul, Minnesota 55108, USA.
Journal of the American Chemical Society
|July 9, 2004
まとめ
研究者らは,光系II (PSII) の新しい改変アミノ酸を特定した. この発見は,この重要な光合成タンパク質複合体の機能に不可欠なカルボニルを含む残基に光を当てています.
科学分野:
- バイオケミストリー バイオケミストリー
- 光合成の研究研究である.
- プロテオミクス プロテオミクスは,プロテオミクスの
背景:
- 酸素による光合成は,水の酸化とプラストキノン還元のために光システムII (PSII) に依存しています.
- 3つのPSIIサブユニットは,アミンとフェニルヒドラジンを結合する反応性グループを有し,カルボニルを含む改変を示唆しています.
- これらの変更は,アミノ酸の共同またはポスト翻訳的変化を含むと仮定されています.
研究 の 目的:
- 光系IIのCP47サブユニット内の特定の改変されたアミノ酸残基を特定する.
- PSIIサブユニットのカルボニル含有反応基の性質を調査する.
主な方法:
- タンデム質量スペクトロメトリーは,CP47サブユニットを分析するために使用されました.
- 改変された残留物は,特にカルボニル基を標識するバイオチン-LC-ヒドラジドまたはバイオチンヒドラジドを使用して親和性タグ付けされました.
- アフィニティ浄化に続いて,タンデム質量スペクトロメトリにより,ヒドラジドラベル付ペプチドが特定されました.
主要な成果:
- シーケンスXKEGRを持つヒドラジドラベルペプチドが特定されました.
- 定量ペプチドマッピングとメチラミンラベリングは,これらの発見を裏付けました.
- 遺伝子配列と質量スペクトロメトリーデータは",X"が改変されたアスパルティック酸残留物であることを予測しています.
結論:
- CP47サブユニットの位置348 (D348) にあるアスパルティック酸に新しいアミノ酸改変であるアスパルチルアルデヒドが提案されています.
- この変化が,PSII.で観察された反応性カルボニル基を説明している可能性が高い.
- この発見は,光システムIIの構造的・機能的な複雑さを理解するのに役立つ.
さらに関連する動画
関連する概念動画
Protein Modifications in the RER
Modification of secretory and transmembrane proteins entering the rough ER begins in the ER lumen. These modifications aid in protein folding and stabilize the acquired tertiary structure. Protein modifications in the rough ER co-occur at different stages of protein folding.
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.
Covalently Linked Protein Regulators
Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an important role in the function and stability of these proteins. Covalently linked molecules include functional groups, such as methyl, acetyl, and phosphate groups, and also small proteins, such as ubiquitin. There are around 200 different types of covalent regulators that have been identified.
These groups modify specific amino acids in a protein.
These groups modify specific amino acids in a protein.
Allosteric Proteins-ATCase
Binding sites linkages can regulate a protein's function. For example, enzyme activity is often regulated through a feedback mechanism where the end product of the biochemical process serves as an inhibitor.
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
Protein Glycosylation
Glycosylation, the most common post-translational modification for proteins, serves diverse functions. Adding sugars to proteins makes the proteins more resistant to proteolytic digestion. Glycosylated proteins can act as markers and receptors to promote cell-cell adhesion. Additionally, they have many essential quality control functions in the cell, such as correct protein folding and facilitating transport of misfolded proteins to the cytosol, which can be degraded.
Glycosylation occurs in...
Glycosylation occurs in...
RNA Editing
RNA editing is a post-transcriptional modification where a precursor mRNA (pre-mRNA) nucleotide sequence is changed by base insertion, deletion, or modification. The extent of RNA editing varies from a few hundred bases, in mitochondrial DNA of trypanosomes, to a just single base, in nuclear genes of mammals. Even a single base change in the pre-mRNA can convert a codon for one amino acid into the codon for another amino acid or a stop codon. This type of re-coding can significantly affect the...
Protein Folding Quality Check in the RER
ER is the primary site for the maturation and folding of soluble and transmembrane secretory proteins. The calnexin cycle is a specific chaperone system that folds and assesses the confirmation of N-glycosylated proteins before they can exit the ER lumen. The primary players of this quality check pipeline are the lectins, ER-resident chaperones, and a glucosyl transferase enzyme. In case the calnexin system in the lumen fails to salvage a misfolded protein, it is transported to the cytoplasm...


