title: Calcium-dependent interaction of calmodulin with human 80S ribosomes and polyribosomes.
abstract: Ribosomes are the protein factories of every living cell. The process of protein translation is highly complex and tightly regulated by a large number of diverse RNAs and proteins. Earlier studies indicate that Ca(2+) plays a role in protein translation. Calmodulin (CaM), a ubiquitous Ca(2+)-binding protein, regulates a large number of proteins participating in many signaling pathways. Several 40S and 60S ribosomal proteins have been identified to interact with CaM, and here, we report that CaM binds with high affinity to 80S ribosomes and polyribosomes in a Ca(2+)-dependent manner. No binding is observed in buffer with 6 mM Mg(2+) and 1 mM EGTA that chelates Ca(2+), suggesting high specificity of the CaM-ribosome interaction dependent on the Ca(2+) induced conformational change of CaM. The interactions between CaM and ribosomes are inhibited by synthetic peptides comprising putative CaM-binding sites in ribosomal proteins S2 and L14. Using a cell-free in vitro translation system, we further found that these synthetic peptides are potent inhibitors of protein synthesis. Our results identify an involvement of CaM in the translational activity of ribosomes.
authors.affiliation: Biophysical Chemistry and Biochemistry, Lund University, Chemical Centre, P.O. Box 124, SE-221 00 Lund, Sweden. petrabehnen@web.de
authors.forename: Petra
authors.initials: P
authors.lastname: Behnen
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Davis
authors.forename: Erin
authors.initials: E
authors.lastname: Delaney
authors.forename: Birgitta
authors.initials: B
authors.lastname: Frohm
authors.forename: Mikael
authors.initials: M
authors.lastname: Bauer
authors.forename: Tommy
authors.initials: T
authors.lastname: Cedervall
authors.forename: David
authors.initials: D
authors.lastname: O'Connell
authors.forename: Karin S
authors.initials: KS
authors.lastname: Åkerfeldt
authors.forename: Sara
authors.initials: S
authors.lastname: Linse
mesh_terms: D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D002147:Calmodulin / Q000737:chemistry / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D011132:Polyribosomes / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism*
chemical_list: D002147:Calmodulin; D002118:Calcium