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Calmodulin activation of target enzymes. Consequences of deletions in the central helix

, : Calmodulin activation of target enzymes. Consequences of deletions in the central helix. Journal of Biological Chemistry 265(7): 3750-3756

The central helical region of calmodulin (CaM) includes amino acids 65-92 and serves to separate the two pairs of Ca2(+)-binding sites. This region may impart conformational flexibility and also interact with target proteins. The functional effects of deleting two, three, five, or eight amino acids from the central helix were monitored by examining the activation of phosphodiesterase, smooth muscle myosin light chain (MLC) kinase, and Ca2+/CaM-dependent protein kinase II (CaM kinase II). CaMDM(-8), a calmodulin-deletion mutant with 8 amino acids deleted from the middle of the central helix, failed to activate MLC kinase, phosphodiesterase, or CaM kinase II at physiologically significant concentrations of activator but also had altered electrophoretic mobility and tyrosine fluorescence properties suggesting major changes in the structure of this mutant. Deletion of five amino acids (77-81) resulted in an increase in apparent Kact for phosphodiesterase (150-fold), CaM kinase II (25-fold), and MLC kinase (5-fold) relative to CaM. The maximal autophosphorylation activity of CaM kinase II was also diminished 70% with CaMDM(-5). For phosphodiesterase activation, CaMDM(-2) has a 15-fold increase in apparent Kact while CaMDM(-3) had an apparent Kact value only 3-fold higher than native CaM. In contrast, the activation of MLC kinase by the two (79-80)- and three (79-81)-amino acid deletion mutants were indistinguishable from each other or native CaM. CaMDM(-2) and CaMDM(-3) stimulated CaM kinase II autophosphorylation to 85 and 70%, respectively, of native CaM with less than a 2-fold increase in Kact. Therefore, all deletions in the central helix of CaM reduce the efficiency of phosphodiesterase activation as reflected by substantial alterations in Kact. MLC kinase activation, however, is relatively insensitive to small two or three amino acid deletions. CaM kinase II interacts with the central helix deletion mutants in a complex manner with alterations in both the Kact and the maximum activity. The data suggest the central helix of CaM may serve as a flexible tether for MLC kinase (and to a lesser extent CaM kinase II) but that an extended conformation of CaM, as predicted from the crystal structure, may be required for phosphodiesterase activation.


PMID: 2154485

Other references

Means J.A., 1976: Sunoco Felda and West Sunoco Felda fields, Hendry, Collier and Lee counties, Florida. Transactions - Gulf Coast Association of Geological Societies 26): 73

Retterstøl, N., 1992: Suicidal trends in Norway and Scandinavia. Tidsskrift for den Norske Laegeforening 112(1): 15-15

Sanders A.F., 1986: Drugs driving and the measurement of human performance. O'hanlon, J F And J J De Gier (Ed ) Drugs And Driving; First International Symposium on Prescription Drugs And Driving Performance, Vinkeveen, Netherlands, June 25-28, 1984 Xiv+402p Taylor And Francis: London, England, Uk; Philadelphia, Pennsylvania, Usa Illus 3-16

Perel'man, V.M.; Prokhorov, A.V.; Shotemor, S.Sh.; Zakharova, E.I., 1989: Clinico-roentgenologic characteristics of postoperative osteitis of the pubic bones. The paper is concerned with clinicoroentgenological analysis of postoperative osteitis of the pubic bones (OPB) in 29 patients with urological diseases. The development of OPB follows operative complications, mainly of pyoinflammatory type. Clinic...

Lubitz, W.; Ogata, H.; Rüdiger, O.; Reijerse, E., 2015: Hydrogenases. Chemical Reviews 114(8): 4081-4148

Dickenson M.; Schwarz R.; Coughenour L.; Tecle H.; Davis R.E., 1988: Partial muscarinic agonists and selective tissue response. Society for Neuroscience Abstracts 14(2): 1329

Tovar, L.; Diaz, A.; Arnal, E.; Ramis, C., 2005: La diversidad isoenzimatica de Bemisia tabaci Gennadius 1889 (Hemiptera: Aleyrodidae) en el cultivo del ajonjoli (Sesamum indicum L) en Venezuela. To characterize the magnitude and structure of the genetic diversity existing within a Bemisia tabaci population in the sesame cultivated region, seven subpopulations of B. tabaci sampled on the crop in different localities or environments were st...

Lohrke, S.M.; Orf, J.H.; Martinez-Romero, E.; Sadowsky, M.J., 1995: Host-Controlled Restriction of Nodulation by Bradyrhizobium japonicum Strains in Serogroup 110. We previously reported the identification of a soybean plant introduction (PI) genotype, PI 417566, which restricts nodulation by Bradyrhizobium japonicum MN1-1c (USDA 430), strains in serogroup 129, and USDA 110 (P. B. Cregan, H. H. Keyser, and M...

Wagenaar, D.A.; Nadasdy, Z.; Potter, S.M., 2006: Persistent dynamic attractors in activity patterns of cultured neuronal networks. Three remarkable features of the nervous system--complex spatiotemporal patterns, oscillations, and persistent activity--are fundamental to such diverse functions as stereotypical motor behavior, working memory, and awareness. Here we report that...

Haller, R.M.; Deluty, R.H., 1990: Characteristics of psychiatric inpatients who assault staff severely. Journal of Nervous and Mental Disease 178(8): 536-537