Coilin phosphorylation mediates interaction with SMN and SmB

• Published in: Chromosoma Vol. 119; no. 2; pp. 205 - 215
• Main Authors: Toyota, Cory G., Davis, Misty D., Cosman, Angela M., Hebert, Michael D.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.04.2010; Springer Nature B.V
• Subjects: Amino Acid Substitution; Animal Genetics and Genomics; Biochemistry; Biomedical and Life Sciences; Cell Biology; Cell Line; Coiled Bodies - metabolism; Developmental Biology; Eukaryotic Microbiology; Human Genetics; Humans; Immunoprecipitation; Life Sciences; Nuclear Proteins - chemistry; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; Phosphorylation; Protein Binding; Protein Structure, Tertiary; Research Article; Ribonucleoproteins, Small Nuclear - metabolism; snRNP Core Proteins - chemistry; snRNP Core Proteins - metabolism; Survival of Motor Neuron 1 Protein - chemistry; Survival of Motor Neuron 1 Protein - metabolism; Immunoprecipitation Reaction; Subnuclear Domain; Normal Mouse Serum; C214 Fragment; HeLa Lysate
• ISSN: 0009-5915; 1432-0886
• DOI: 10.1007/s00412-009-0249-x

Cajal bodies (CBs) are subnuclear domains that participate in spliceosomal small nuclear ribonucleoprotein (snRNP) biogenesis and play a part in the assembly of the spliceosomal complex. The CB marker protein, coilin, interacts with survival of motor neuron (SMN) and Sm proteins. Several coilin phosphoresidues have been identified by mass spectrometric analysis. Phosphorylation of coilin affects its self-interaction and localization in the nucleus. We hypothesize that coilin phosphorylation also impacts its binding to SMN and Sm proteins. In vitro binding studies with a C-terminal fragment of coilin and corresponding phosphomimics show that SMN binds preferentially to dephosphorylated analogs and that SmB′ binds preferentially to phosphomimetic constructs. Bacterially expressed full-length coilin binds more SMN and SmB′ than does the C-terminal fragment. Co-immunoprecipitation and phosphatase experiments show that SMN also binds dephosphorylated coilin in vivo. These data show that phosphorylation of coilin influences interaction with its target proteins and, thus, may be significant in managing the flow of snRNPs through the CB.