Mutations in paramecium calmodulin indicate functional differences between the C-terminal and N-terminal lobes in vivo

Kink, John A.; Maley, Margot E.; Preston, Robin R.; Ling, Kit‐Yin; Wallen-Friedman, Margaret A.; Saimi, Yoshiro; Kung, Ching

doi:10.1016/0092-8674(90)90250-i

Cited by 136 publications

(96 citation statements)

References 45 publications

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“…We consider gene duplication more likely than a past step of polyploidization, as single-copy genes, like that of calmodulin (Kink et al, 1990), are present in the genome of Paramecium tetraurelia. It is also conceivable that the different versions of the ICLl genes are created during the macronuclear differentiation process, as in ciliates the transcriptionally active polyploid macronucleus (somatic line) derives from the transcriptionally inactive diploid micronucleus (germ line) through extensive DNA rearrangements (Blackburn and Karrer, 1986).…”

Section: Discussionmentioning

confidence: 99%

“…The ICLla deduced amino acid sequence shares 55.6% identity with Chlamydomunas centrin (Huang et al, 1988) and ~5 0 % identity with human centrins (50.6% with Hcenl, Lee and Huang, 1993;49.3% with Hcen2, Errabolu et al, 1994) as compared to only 42.7% identity with Paramecium calmodulin (Kink et al, 1990). An alignment of the ICLla Paramecium centrin sequence with sequences of centrins from other species is shown in Fig.…”

Section: The Icll Genes Code For Centrins Comparison Of the Icllamentioning

confidence: 99%

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Characterization of Centrin Genes in Paramecium

Madeddu

Klotz

Caër³

et al. 1996

European Journal of Biochemistry

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Centrins are highly conserved, ubiquitous cytoskeletal components which belong to the EF-hand superfamily of Caz+-modulated proteins. We report here the molecular characterization of new members of the centrin family, Paranzecium centrins. Previous studies described the organization of the infraciliary lattice (ICL), the innermost cortical cytoskeletal network of Paramecium, and showed that it was composed of a set of low-molecular-mass, Ca*+-binding polypeptides [Garreau de Loubresse, N., Klotz, C., Vigues, B., Rutin, J. & Beisson, J. ) Bid. Cell 71, 217-2251. In this paper we show that these polypeptides are recognized by specific anti-centrin polyclonal antibodies. Their microsequences revealed four distinct N-termini. For one of them, ICLI, N-terminal and internal peptide sequences were used for PCR amplification and cloning of a DNA fragment containing a complete centrin coding sequence. The deduced amino acid sequence presents about 50% identity with those of centrins from other species. Further molecular analysis allowed us to identify two additional closely related, co-expressed ICLl genes, providing the first example of a centrin multigenic family in a microorganism.

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Section: Discussionmentioning

confidence: 99%

Section: The Icll Genes Code For Centrins Comparison Of the Icllamentioning

confidence: 99%

Characterization of Centrin Genes in Paramecium

Madeddu

Klotz

Caër³

et al. 1996

European Journal of Biochemistry

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“…The former mutants have little or no Ca2'-calmodulin activated Na' currents, the latter mutants have reduced Ca"-calmodulin activated K' currents. Of the 12 mutations scrutinized, none were found in the central helix [8,9] (Fig. 3).…”

Section: Mutants and Functional Bipartition Of Calmodulin In Vivomentioning

confidence: 99%

Ion channel regulation by calmodulin binding

Saimi

Kung

1994

FEBS Letters

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While many ion channels are modulated by phosphorylation, there is growing evidence that they can also be regulated by Ca*'calmodulin, apparently through direct binding. In some cases, this binding activates channels; in others, it modulates channel activities. These phenomena have been documented in Paramecium, in Drosophila, in vertebrate photoreceptors and olfactory receptors, as well as in ryanodine receptor Ca*'-release channels. Furthermore, studies on calmodulin mutants in Paramecium have shown a clear bipartite distribution of two groups of mutations in the calmodulin gene that lead to opposite behavioral and electrophysiological phenotypes. These results indicate that the N-lobe of calmodulin specifically interacts with one class of ion-channel proteins and the C-lobe with another.

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“…This suggests discrete and opposing roles for the two domains in the generation of proper muscle responses, and is strikingly similar to the opposing effects of N-and C-terminal CaM mutations on behavioral responses in Paramecium (Kink et al, 1990).…”

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confidence: 65%

“…Moreover, there is now evidence that the two domains have different regulatory roles. Most strikingly, in Paramecium, mutations in the N-terminal lobe of CaM affect Ca 2ϩ -activated Na ϩ channel currents, resulting in sluggish, unresponsive behavior, whereas C-terminal lobe mutations alter Ca 2ϩ -activated K ϩ currents (Kink et al, 1990), producing hyperexcitability. Thus, the structural bipartition of CaM may permit functional bipartition in terms of regulating Ca 2ϩ -sensitive targets (Ling et al, 1994).…”

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confidence: 99%