Related Experiment Video
Updated: Jun 17, 2025
08:48
Specificity Analysis of Protein Lysine Methyltransferases Using SPOT Peptide Arrays
Published on: November 29, 2014
13.9K
Structural Basis of Substrate Recognition by the Postmitosane Modification Enzyme MitM in Mitomycin Biosynthesis
Danna Dong1, Mingyu Xia2, Sili Wang2
1Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei 230026, China.
Biochemistry
|August 14, 2024
Summary
MitM, an enzyme in Streptomyces, methylates compounds for antibiotic and antitumor mitomycin production. Structural analysis reveals how MitM binds its substrate and cofactor, offering insights for enzyme engineering.
Area of Science:
- Biochemistry
- Structural Biology
- Microbiology
Background:
- Mitomycins are natural products from Streptomyces with antibacterial and antitumor properties.
- MitM is a crucial enzyme in mitomycin biosynthesis, acting as an N-methyltransferase.
- The structural mechanisms of MitM's substrate and cofactor recognition were previously unknown.
Purpose of the Study:
- To elucidate the structural basis of MitM's recognition of S-adenosyl-l-methionine (SAM) and mitomycin A.
- To understand the role of MitM in the postmitosane modification during mitomycin biosynthesis.
Main Methods:
- Determination of crystal structures of apo-MitM and a MitM-mitomycin A-S-adenosylhomocysteine (SAH) ternary complex.
- Analysis of protein structure, including active site residues and conformational changes.
Main Results:
- MitM exhibits a class I SAM-dependent methyltransferase fold and forms a homodimer.
- Conformational changes, particularly in the 28ALGAASLGE36 loop, facilitate binding of SAH and mitomycin A.
- The 28ALGAASLGE36 loop undergoes a significant conformational change upon mitomycin A binding, transitioning the active site from open to closed.
Conclusions:
- The study provides key structural insights into the function of MitM in mitomycin biosynthesis.
- The findings offer a structural template for potential engineering of methyltransferase enzymes.
Related Concept Videos
01:19Translocation of Proteins into the Mitochondria
3.1K
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,...
3.1K
01:39Mitochondrial Precursor Proteins
2.5K
Mitochondrial precursors are partially unfolded or loosely folded polypeptide chains. Newly synthesized precursors are inhibited from spontaneously folding into their native conformation by the cytosolic chaperones, heat shock proteins 70 (Hsp70), and mitochondrial import stimulation factors (MSFs). Precursors bound to MSFs are guided to the TOM70-TOM37 receptors, while precursors bound to Hsp70 chaperones are targetted to TOM20-TOM22 receptor complexes.
Most of the mitochondrial...
Most of the mitochondrial...
2.5K
01:48ATP Synthase: Mechanism
14.2K
In animals, the mitochondrial F1F0 ATP synthase is the key protein that synthesizes ATP molecules through a complex catalytic mechanism. While the nuclear genome encodes the majority of ATP synthase subunits, the mitochondrial genome encodes some of the enzyme's most critical components. The formation of this multi-subunit enzyme is a complex multi-step process regulated at the level of transcription, translation, and assembly. Defects in one or more of these steps can result in decreased...
14.2K
01:19Allosteric Proteins-ATCase
5.7K
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...
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...
5.7K
01:17Phase II Reactions: Methylation Reactions
164
Methylation is a phase II biotransformation process involving the attachment of a methyl group to a substrate. Enzymes known as methyltransferases orchestrate this reaction.
The mechanism of methylation unfolds in two stages. The first stage sees a methyltransferase enzyme facilitating the transfer of a methyl group from S-adenosylmethionine (SAM) to the substrate, forming S-adenosylhomocysteine (SAH). The second stage involves further metabolism of SAH into homocysteine, which can be recycled...
The mechanism of methylation unfolds in two stages. The first stage sees a methyltransferase enzyme facilitating the transfer of a methyl group from S-adenosylmethionine (SAM) to the substrate, forming S-adenosylhomocysteine (SAH). The second stage involves further metabolism of SAH into homocysteine, which can be recycled...
164
01:39Mitochondrial Protein Sorting
4.3K
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...
4.3K