RGD Reference Report - Structural requirements of tropomodulin for tropomyosin binding and actin filament capping. - Rat Genome Database

Send us a Message
Submit Data |  Help |  Video Tutorials |  News |  Publications |  Download |  REST API |  Citing RGD |  Contact   
Search RGD Grant Resources Citing RGD About Us Contact Us
Genes Variants Community Projects QTLs Strains Markers Genome Information Ontologies Cell Lines References Download Submit Data
OntoMate (Literature Search) JBrowse (Genome Browser) Synteny Browser (VCMap) Variant Visualizer Multi-Ontology Enrichment (MOET) Gene-Ortholog Location Finder (GOLF) InterViewer (Protein-Protein Interactions) PhenoMiner (Quatitative Phenotypes) Gene Annotator OLGA (Gene List Generator) AllianceMine GViewer (Genome Viewer)
Aging & Age-Related Disease Cancer & Neoplastic Disease Cardiovascular Disease Coronavirus Disease Developmental Disease Diabetes Hematologic Disease Immune & Inflammatory Disease Infectious Disease Liver Disease Neurological Disease Obesity & Metabolic Syndrome Renal Disease Respiratory Disease Sensory Organ Disease
Find Models   new Genetic Models Autism Models Rat PhenoMiner (Quantitative Phenotypes) Chinchilla PhenoMiner Expected Ranges (Quantitative Phenotype) PhenoMiner Term Comparison Hybrid Rat Diversity Panel Phenotypes Phenotypes in Other Animal Models Animal Husbandry Strain Medical Records Phylogenetics Strain Availability Calendar Rats 101 Submissions Photo Archive
Pathways
Rat Community Forum Directory of Rat Laboratories Video Tutorials News RGD Publications RGD Presentations Archive Nomenclature Guidelines Resource Links Laboratory Resources Employment Resources

Structural requirements of tropomodulin for tropomyosin binding and actin filament capping.

Authors: Kostyukova, AS  Rapp, BA  Choy, A  Greenfield, NJ  Hitchcock-DeGregori, SE 
Citation: Kostyukova AS, etal., Biochemistry. 2005 Mar 29;44(12):4905-10.
RGD ID: 1600523
Pubmed: PMID:15779917   (View Abstract at PubMed)
DOI: DOI:10.1021/bi047468p   (Journal Full-text)

Regulation of actin filament dynamics underlies many cellular functions. Tropomodulin together with tropomyosin can cap the pointed, slowly polymerizing, filament end, inhibiting addition or loss of actin monomers. Tropomodulin has an unstructured N-terminal region that binds tropomyosin and a folded C-terminal domain with six leucine-rich repeats. Of tropomodulin 1's 359 amino acids, an N-terminal fragment (Tmod1(1)(-)(92)) suffices for in vitro function, even though the C-terminal domain can weakly cap filaments independent of tropomyosin. Except for one short alpha-helix with coiled coil propensity (residues 24-35), the Tmod1(1)(-)(92) solution structure shows that the fragment is disordered and highly flexible. On the basis of the solution structure and predicted secondary structure, we have introduced a series of mutations to determine the structural requirements for tropomyosin binding (using native gels and CD) and filament capping (by measuring actin polymerization using pyrene fluorescence). Tmod1(1)(-)(92) fragments with mutations of an interface hydrophobic residue, L27G and L27E, designed to destroy the alpha-helix or coiled coil propensity, lost binding ability to tropomyosin but retained partial capping function in the presence of tropomyosin. Replacement of a flexible region with alpha-helical residues (residues 59-61 mutated to Ala) had no effect on tropomyosin binding but inhibited the capping function. A mutation in a region predicted to be an amphipathic helix (residues 65-75), L71D, destroyed the capping function. The results suggest that molecular flexibility and binding to actin via an amphipathic helix are both required for tropomyosin-dependent capping of the pointed end of the actin filament.

Gene Ontology Annotations    Click to see Annotation Detail View

Biological Process
TermQualifierEvidenceWithReferenceNotesSourceOriginal Reference(s)
actin filament capping  IDA 1600523; 1600523 RGD 

Molecular Function
TermQualifierEvidenceWithReferenceNotesSourceOriginal Reference(s)
protein binding  IPIUniProtKB:Q9DEA61600523; 1600523protein N-terminus bindingRGD 

Objects Annotated

Genes (Rattus norvegicus)
Tpm1  (tropomyosin 1)
Tpm1_v7  (tropomyosin 1, variant 7)

Objects referenced in this article
Gene Tpm1_v1 tropomyosin 1, variant 1 Rattus norvegicus
Gene Tpm1_v2 tropomyosin 1, variant 2 Rattus norvegicus
Gene Tpm1_v3 tropomyosin 1, variant 3 Rattus norvegicus
Gene Tpm1_v4 tropomyosin 1, variant 4 Rattus norvegicus
Gene Tpm1_v5 tropomyosin 1, variant 5 Rattus norvegicus
Gene Tpm1_v6 tropomyosin 1, variant 6 Rattus norvegicus
Gene Tpm1_v8 tropomyosin 1, variant 8 Rattus norvegicus
Gene Tpm1_v9 tropomyosin 1, variant 9 Rattus norvegicus

Additional Information