GO:0018025 calmodulin-lysine N-methyltransferase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0018025 describes the enzymatic activity that transfers methyl groups from S-adenosyl-L-methionine to lysine residues on calmodulin, producing S-adenosyl-L-homocysteine and N6-methyl-L-lysine calmodulin.
• The enzyme responsible, calmodulin-lysine N-methyltransferase (CaM KMT), is evolutionarily conserved and specifically trimethylates lysine 115 of calmodulin in many organisms.
• This post-translational modification modulates calmodulin's ability to regulate downstream targets, including the caspase-11 non-canonical inflammasome, thereby influencing inflammatory responses.
• Human calmodulin methyltransferase activity depends on Hsp90 and can be studied using recombinant calmodulin and methyltransferase assays.
• Dysregulation of calmodulin methylation has been linked to altered inflammatory signaling and may contribute to diseases involving uncontrolled inflammation.
• CRISPR-based knockout, point-mutation, and knock-in models are powerful tools to dissect the physiological roles of calmodulin-lysine N-methyltransferase activity in cells and organisms.
Description
Calmodulin-lysine N-methyltransferase activity (GO:0018025) is a molecular function that catalyzes the methylation of specific lysine residues on calmodulin, a ubiquitous calcium-sensing protein. This activity uses S-adenosyl-L-methionine as the methyl donor and produces S-adenosyl-L-homocysteine and calmodulin containing N6-methyl-L-lysine. The modification is conserved across evolution and has been detected in organisms ranging from Paramecium to mammals. Researchers study this activity because it alters calmodulin's surface properties and its interactions with target enzymes, thereby influencing calcium signaling pathways. Recent work has highlighted a role for calmodulin trimethylation in suppressing the caspase-11 non-canonical inflammasome, linking this enzymatic activity to innate immunity and inflammation. Understanding GO:0018025 is therefore important for deciphering how post-translational modifications fine-tune calmodulin function in health and disease.
calmodulin-lysine N-methyltransferase activity At A Glance
| GO ID | GO:0018025 |
|---|---|
| GO term | calmodulin-lysine N-methyltransferase activity |
| Ontology | molecular_function |
| Synonym | S-adenosyl-L-methionine:calmodulin-L-lysine 6-N-methyltransferase activity; S-adenosyl-L-methionine:calmodulin-L-lysine N6-methyltransferase activity; S-adenosylmethionine:calmodulin (lysine) N-methyltransferase activity |
| Major function | Catalyzes the transfer of a methyl group from S-adenosyl-L-methionine to a lysine residue on calmodulin, forming N6-methyl-L-lysine calmodulin and S-adenosyl-L-homocysteine. |
| Substrate | Calmodulin L-lysine (typically Lys-115 in calmodulin). |
| Cofactor | S-adenosyl-L-methionine as methyl donor. |
| Product | S-adenosyl-L-homocysteine and calmodulin N6-methyl-L-lysine. |
| Enzyme class | Methyltransferase (EC 2.1.1.-). |
| Conservation | Evolutionarily conserved from protozoa to mammals. |
What Is GO:0018025?
In simple terms, GO:0018025 is the enzyme activity that attaches methyl groups to lysine on calmodulin. The official definition is: Catalysis of the reaction: S-adenosyl-L-methionine + calmodulin L-lysine = S-adenosyl-L-homocysteine + calmodulin N6-methyl-L-lysine. This activity is also known as S-adenosyl-L-methionine:calmodulin-L-lysine 6-N-methyltransferase activity, S-adenosyl-L-methionine:calmodulin-L-lysine N6-methyltransferase activity, and S-adenosylmethionine:calmodulin (lysine) N-methyltransferase activity.
Why Is calmodulin-lysine N-methyltransferase activity Important in Cell Biology?
Calmodulin-lysine N-methyltransferase activity is important because it introduces a post-translational modification that can alter calmodulin's ability to bind and activate downstream targets. This modification has been implicated in regulating inflammatory signaling, particularly through the caspase-11 non-canonical inflammasome pathway. Because calmodulin is a central calcium sensor involved in countless cellular processes, understanding how its methylation is controlled provides insight into basic cell biology and potential therapeutic avenues for inflammatory diseases.
• Regulates calmodulin function by adding methyl groups to lysine residues, affecting its interaction with target proteins.
• Modulates innate immune responses by suppressing caspase-11 non-canonical inflammasome activation.
• Is evolutionarily conserved, suggesting a fundamental role in cellular physiology.
• Provides a mechanism for fine-tuning calcium signaling pathways.
• May be involved in neurobiological processes, as calmodulin methylation has been detected in brain tissue.
• Offers a potential target for anti-inflammatory therapies.
• Can be studied using recombinant enzymes and specific methyltransferase assays.
• Its dependence on Hsp90 in human cells links it to protein folding and stability networks.
• Dysregulation may contribute to diseases characterized by abnormal inflammation.
• CRISPR-based models enable precise dissection of its physiological roles.
What Happens During calmodulin-lysine N-methyltransferase activity?
Substrate Recognition and Binding
In simple terms: The enzyme first grabs onto calmodulin, the protein it will modify.
Calmodulin-lysine N-methyltransferase specifically recognizes calmodulin as a substrate. In vitro studies using purified enzymes from Paramecium and rat brain have shown that the methyltransferase binds calmodulin in a calcium-dependent manner, although the exact binding determinants may vary by organism. The enzyme targets a specific lysine residue, typically Lys-115 in vertebrate calmodulin, which is located in a flexible central helix.
Methyl Group Transfer
In simple terms: The enzyme takes a methyl group from SAM and attaches it to the lysine on calmodulin.
Using S-adenosyl-L-methionine (SAM) as the methyl donor, the enzyme catalyzes the transfer of a methyl group to the epsilon-amino group of the target lysine, forming N6-methyl-L-lysine and releasing S-adenosyl-L-homocysteine (SAH). This reaction can proceed to trimethylation, as the enzyme has been shown to trimethylate Lys-115 in calmodulin.
Trimethylation and Product Formation
In simple terms: The enzyme can add up to three methyl groups, creating trimethylated calmodulin.
Calmodulin methyltransferase from various species, including humans, is capable of successive methylation events leading to trimethylation of Lys-115. The trimethylated calmodulin is the final product, which may exhibit altered functional properties compared to unmethylated calmodulin.
Regulation by Hsp90 and Cellular Context
In simple terms: In human cells, the enzyme needs Hsp90, a chaperone, to work properly.
Human calmodulin methyltransferase activity is dependent on the chaperone Hsp90, as demonstrated by in vitro assays and cellular studies. This dependence suggests that the enzyme's stability or activity is regulated by the cellular protein-folding environment, linking calmodulin methylation to broader cellular stress responses.
Key Genes Involved in GO:0018025 calmodulin-lysine N-methyltransferase activity
The following genes and proteins are directly involved in or regulate calmodulin-lysine N-methyltransferase activity (GO:0018025).
| Gene | Major Role | Research Relevance |
|---|---|---|
| CaM KMT (calmodulin-lysine N-methyltransferase) | Catalyzes the methylation of calmodulin at Lys-115 | Core enzyme for GO:0018025; target for knockout and activity assays |
| CALM1 (calmodulin 1) | Substrate for methylation; calcium sensor | Methylation alters its function; point mutations at Lys-115 can block modification |
| CALM2 (calmodulin 2) | Substrate for methylation; calcium sensor | Similar to CALM1; potential redundancy in methylation targets |
| CALM3 (calmodulin 3) | Substrate for methylation; calcium sensor | May be differentially methylated in specific tissues |
| HSP90AA1 (Hsp90 alpha) | Chaperone required for human calmodulin methyltransferase activity | Modulates enzyme stability and function; target for inhibitor studies |
| CASP11 (caspase-11) | Downstream effector of non-canonical inflammasome | Calmodulin methylation suppresses its activation; knockout models available |
| CASP4 (caspase-4, human homolog of caspase-11) | Involved in non-canonical inflammasome in humans | Potential target for anti-inflammatory interventions |
| SAM (S-adenosylmethionine) metabolic enzymes | Provide methyl donor for the reaction | Modulate substrate availability; can be targeted to alter methylation |
| SAH hydrolase | Metabolizes S-adenosyl-L-homocysteine, product of the reaction | Regulates feedback inhibition; potential indirect regulator |
| Paramecium CaM KMT | Model enzyme for purification and characterization | Used to define enzymatic properties and substrate specificity |
| Rat brain CaM KMT | Endogenous enzyme studied in neurobiology | Relevant for neurological research and brain methylation studies |
| Human CaM KMT | Recombinant enzyme for activity assays | Used to study Hsp90 dependence and inhibitor screening |
| Calmodulin-dependent kinases | Downstream targets affected by calmodulin methylation | Methylation may alter kinase activation; research models to test signaling |
| Calcineurin | Calmodulin-dependent phosphatase | Potential target whose regulation may be influenced by calmodulin methylation |
| Plasma membrane Ca2+ ATPase | Calmodulin-regulated pump | May be affected by methylation status of calmodulin |
| Nitric oxide synthase | Calmodulin-dependent enzyme | Methylation could modulate NO production; relevant to inflammation |
| Adenylyl cyclase | Calmodulin-sensitive enzyme | Potential downstream effect of calmodulin methylation |
| Caspase-1 | Inflammasome effector | May be indirectly affected by calmodulin methylation via caspase-11 |
How Is calmodulin-lysine N-methyltransferase activity Regulated?
Calmodulin-lysine N-methyltransferase activity is regulated at multiple levels. In human cells, the enzyme's activity depends on the chaperone Hsp90, which likely maintains its proper folding or stability. The availability of the methyl donor S-adenosylmethionine and the accumulation of the product S-adenosyl-L-homocysteine can influence reaction rates through feedback inhibition. Additionally, the methylation status of calmodulin itself may be subject to dynamic regulation, as the enzyme can perform successive methylations leading to trimethylation. In inflammatory contexts, the activity of calmodulin-lysine N-methyltransferase appears to be modulated to suppress caspase-11 non-canonical inflammasome activation, suggesting that upstream signals can regulate its function.
calmodulin-lysine N-methyltransferase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CaM KMT | Inflammatory diseases (e.g., sepsis, colitis) | Knockout mice or macrophages to assess caspase-11 activation |
| CALM1 | Calmodulinopathies (e.g., long QT syndrome, CPVT) | Point mutation at Lys-115 to block methylation; knock-in mice |
| CASP11 | Non-canonical inflammasome-mediated inflammation | Caspase-11 knockout mice to test epistasis with CaM KMT |
| HSP90AA1 | Inflammation and cancer | Hsp90 inhibitors in cell models to modulate CaM KMT activity |
| CALM2 | Neurological disorders | Brain-specific knockout of CaM KMT to study methylation in neurons |
Inflammation and Innate Immunity
Calmodulin-lysine N-methyltransferase activity plays a protective role in inflammation by suppressing the caspase-11 non-canonical inflammasome. Studies show that trimethylation of calmodulin by this enzyme inhibits caspase-11 activation in macrophages, thereby reducing inflammatory responses. This suggests that loss of this activity could exacerbate inflammatory diseases, while enhancing it might be therapeutic.
Neurological Disorders
Calmodulin methylation has been detected in rat brain and pituitary, indicating a role in neuroendocrine tissues. Although direct links to neurological diseases are not yet established, altered calmodulin methylation could affect calcium signaling in neurons, which is critical for synaptic plasticity and neuronal survival.
Cancer
While no direct evidence links calmodulin-lysine N-methyltransferase activity to cancer in the provided literature, calmodulin is known to regulate cell proliferation and survival pathways. Dysregulation of calmodulin methylation could therefore indirectly influence cancer-related processes, but this remains speculative and requires further investigation.
From calmodulin-lysine N-methyltransferase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the effect of CaM KMT loss on inflammasome activation? | CaM KMT knockout macrophages or mice, followed by caspase-11 activation assays |
| Does Lys-115 methylation of calmodulin affect its interaction with targets? | Point mutation of CALM1 Lys-115 to arginine (unmethylatable) via CRISPR knock-in |
| Can trimethylation of calmodulin be detected in vivo? | Knock-in of tagged calmodulin (e.g., FLAG) for immunoprecipitation and mass spectrometry |
| Does Hsp90 regulate CaM KMT activity in cells? | Hsp90 knockdown or inhibition in human cell lines, measuring methyltransferase activity |
| What is the role of CaM KMT in brain function? | Brain-specific conditional knockout of CaM KMT in mice, behavioral and biochemical assays |
| Can overexpression of CaM KMT suppress inflammation? | Overexpression of CaM KMT in macrophages or mice, followed by LPS challenge |
How to Study the calmodulin-lysine N-methyltransferase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Methyltransferase activity assay | Enzyme activity using radioactive SAM or fluorescence | Purified enzyme characterization |
| Western blot with methyl-specific antibodies | Levels of methylated calmodulin | Cell lysates from knockout or overexpression models |
| Mass spectrometry | Methylation site and stoichiometry | Identification of Lys-115 trimethylation |
| CRISPR-Cas9 knockout | Loss of gene function | Studying CaM KMT role in inflammation |
| CRISPR point mutation | Specific amino acid change (e.g., Lys-115 to Arg) | Testing unmethylatable calmodulin |
| CRISPR knock-in | Tagged or reporter gene | Tracking calmodulin methylation in live cells |
| Overexpression | Increased enzyme levels | Assessing anti-inflammatory effects |
| Inflammasome activation assay | Caspase-11 cleavage and IL-1beta release | Macrophage stimulation with LPS |
Enzymatic Activity Assays
Methyltransferase activity can be measured using purified calmodulin and S-adenosyl-L-methionine, followed by detection of methylated calmodulin or S-adenosyl-L-homocysteine. Classic assays use radioactive SAM and gel electrophoresis or mass spectrometry to quantify methylation.
Mass Spectrometry and Proteomics
Mass spectrometry is essential to identify and quantify methylation sites on calmodulin, such as Lys-115 trimethylation. This approach can be applied to cell lysates or purified protein to confirm the specific modification.
CRISPR-Cas9 Genome Editing
CRISPR-Cas9 is used to generate knockout, point-mutation, and knock-in cell lines to study the function of CaM KMT and calmodulin methylation. For example, knocking out CaM KMT or mutating Lys-115 of calmodulin can reveal downstream effects on inflammasome activation.
Inflammasome Activation Assays
To study the anti-inflammatory role of calmodulin methylation, researchers use macrophage cell lines or primary macrophages, stimulate with LPS and intracellular LPS, and measure caspase-11 activation, IL-1beta secretion, and pyroptosis.
How CRISPR Can Be Used to Study GO:0018025 calmodulin-lysine N-methyltransferase activity
Knockout
CRISPR knockout of CaM KMT or calmodulin genes can abolish calmodulin-lysine N-methyltransferase activity, allowing researchers to study its loss-of-function effects on inflammasome activation and calcium signaling.
Point Mutation
Point mutations, such as substituting Lys-115 of calmodulin with arginine, prevent methylation and can be introduced via CRISPR to dissect the specific contribution of this modification to calmodulin function.
Knock-in
Knock-in of tagged calmodulin (e.g., FLAG or GFP) enables immunoprecipitation and live-cell imaging to track methylation dynamics and localization.
Overexpression
Overexpression of CaM KMT using CRISPR activation or lentiviral vectors can enhance calmodulin methylation and suppress inflammatory pathways, providing a gain-of-function model.
How EDITGENE Supports calmodulin-lysine N-methyltransferase activity Research
Researchers studying calmodulin-lysine N-methyltransferase activity-related genes often need to determine whether a candidate gene is causally involved in inflammatory signaling, calcium regulation, or other cellular processes. EDITGENE provides comprehensive CRISPR-based services to create precisely engineered cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for calmodulin-lysine N-methyltransferase activity research.
Frequently Asked Questions About calmodulin-lysine N-methyltransferase activity
What is calmodulin-lysine N-methyltransferase activity?
It is the enzyme activity that adds methyl groups to lysine residues on calmodulin, using S-adenosyl-L-methionine as a methyl donor, as defined by GO:0018025.
What genes are involved in calmodulin-lysine N-methyltransferase activity?
The core enzyme is encoded by CaM KMT, and its substrate is calmodulin (CALM1, CALM2, CALM3). Hsp90 (HSP90AA1) is required for human enzyme activity.
What is the GO ID for calmodulin-lysine N-methyltransferase activity?
The Gene Ontology ID is GO:0018025.
How does calmodulin methylation affect inflammation?
Trimethylation of calmodulin by CaM KMT suppresses the caspase-11 non-canonical inflammasome, reducing inflammatory responses in macrophages.
Which lysine residue on calmodulin is methylated?
Lysine 115 (Lys-115) is the primary site of trimethylation by calmodulin-lysine N-methyltransferase.
Is calmodulin-lysine N-methyltransferase conserved across species?
Yes, the enzyme is evolutionarily conserved and has been studied in organisms such as Paramecium, rat, and human.
What diseases are linked to calmodulin-lysine N-methyltransferase activity?
Dysregulation has been associated with inflammatory conditions due to its role in suppressing caspase-11 activation.
How can I study calmodulin-lysine N-methyltransferase activity in the lab?
Common methods include enzymatic activity assays, mass spectrometry, and CRISPR-based knockout or point-mutation models.
Does Hsp90 regulate calmodulin-lysine N-methyltransferase?
Yes, human calmodulin methyltransferase activity is dependent on Hsp90, which likely maintains enzyme stability or folding.
What are the products of the calmodulin-lysine N-methyltransferase reaction?
The reaction produces S-adenosyl-L-homocysteine and calmodulin containing N6-methyl-L-lysine.
Conclusion
Calmodulin-lysine N-methyltransferase activity (GO:0018025) is a conserved enzymatic function that modifies calmodulin at Lys-115, influencing calcium signaling and inflammatory pathways. Its role in suppressing the caspase-11 non-canonical inflammasome highlights its potential as a therapeutic target for inflammatory diseases. Continued research using CRISPR models and biochemical assays will further elucidate its physiological and pathological significance.
References
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- 2. Pech LL et al.. 1994. Purification and characterization of calmodulin (lysine 115) N-methyltransferase from Paramecium tetraurelia.. Biochim Biophys Acta 1199(2):183-94 PMID: 8123667
- 3. Rowe PM et al.. 1986. Calmodulin N-methyltransferase. Partial purification and characterization.. J Biol Chem 261(15):7060-9 PMID: 3700427
- 4. Lim HR et al.. 2026. Calmodulin trimethylation by calmodulin-lysine N-methyltransferase plays an anti-inflammatory role by inhibiting caspase-11 noncanonical inflammasome in macrophages.. Microb Pathog 219:108758 PMID: 42575223
- 5. Magen S et al.. 2012. Human calmodulin methyltransferase: expression, activity on calmodulin, and Hsp90 dependence.. PLoS One 7(12):e52425 PMID: 23285036
- 6. Magnani R et al.. 2010. Calmodulin methyltransferase is an evolutionarily conserved enzyme that trimethylates Lys-115 in calmodulin.. Nat Commun 1:43 PMID: 20975703
- 7. Murtaugh TJ et al.. 1986. Posttranslational modification of calmodulin in rat brain and pituitary.. J Neurochem 47(1):164-72 PMID: 3711896
- 8. Sitaramayya A et al.. 1980. Enzymatic methylation of calmodulin in rat brain cytosol.. J Biol Chem 255(18):8894-900 PMID: 6773954
