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Functional models of the C1 complex
J. Mol. Biol. (1987) 195, 437-438
Functional
Models of the Cl Complex
Consensus and Disagreement
(4) They postulate an activation mechanism in Maurice Colomb and Gerard Arlaud describe in a which activation of Clr, in Cl is mediated by recent letter (Colomb & Arlaud, 1987) the genesisof interaction between the catalytic domains (light the model and emphasize identical features of their chain domains) of Cls and Clr, thus inducing model and the one proposed by Weiss et al. (1986). enzymatic activity in the Clr zymogen. We would like to add the following comments. In this respect the work of Schumaker and his In a recent publication, which came to our attention after the submission of our paper, Villiers coworkers (Strang et al., 1982; Poon et al., 1983; see et al. (1985) studied the Cls-Clr,-Cls complex by also Schumaker et al., 1986) should also be electron microscopy. The conclusions reached in acknowledged. In their model, which is based on this report differ in important aspects from our the localization of the Cls-Clr,-Cls complex within the Cl complex (near the kink region of Clq) and model. They deduce from their pictures obtained the beads on a string model of Tschopp et al. (1980), with rotary shadowing: (1) A linear arrangement of the domains in Clr,. the Cls-Clr,-Cls complex is folded in an S-like (2) The dimerization of Clr, via the globular manner around the stems of Clq. This arrangement remains essentially unchanged in subsequently (catalytic) domains. refined models. However, those models (Colomb et (3) The assignment of fragment fl (described by 1984aJ; Weiss et al., 1986) describe the al., Arlaud et al (1980)) to -the rod-like domain structure and domain organization of the Cls-Clr*(described as a short polypeptide strand). Cls complex in more detail. These differences are in our view caused mainly On the basis of physicochemical studies of Cls, by the different staining techniques employed by Clr and fragment ClrII, Colomb et al. (1984a,6) both groups. Due to the decoration effect of the propose a model, where the catalytic domains of metal crystals, the rotary shadowing technique Clr, are localized in the center of the Cls-Clr,-Cls gives rise to exaggerated diameters of small complex and those of Cls at the outside. Clr and domains. The negative staining technique, which Cls bind via their interactive domains to each was used in our analysis, is more useful to detect other. In addition they fold the catalytic domains fine structures, especially in globular proteins, and of Cls back to the inside of the cone of Clq to allow small morphological units appear with more for contact of all catalytic domains and thus realistic dimensions. activation of Cl. Thus, the asymmetric X-like structure of Clr, we Weiss et al. (1986) studied the Cls-Clr,-Cls observed, would appear like a croissant-like complex by electron microscopy and demonstrated structure, if heavily shadowed. Similarly from an that Cls is indeed located at both ends of this earphone-like structure (fragment ClrII), or from a chain. On the basis of electron micrographs of Cls, dumb-bell-shaped molecule (Cls) two large globes Clr,, fragment ClrII (previously described by would result. Arlaud et aZ., 1980), the Cls-Clr,-Cls complex and In fact, the molecules observed by Villiers et al. the binding properties of fragment ClrII and a (1985) are extremely large. Clr,, for example, shows fragment of rabbit Cls (Taniuchi et aZ., 1981), they a length of up to 50 nm (Fig. Z(b) of Villiers et al., derived a model for Cl which contains, in addition 1985), which is about the length of the entire Clsto previous models, the following features: Clr,-Cls complex. (1) Cl r and Cl s monomers are described as composed of three domains: two globular domains We acknowledgefully the contributions by Arlaud, separated by a rod-like domain (rather than a thin Colomband their collaborators,to which eight references filament). can be found in our recent publication (Weisset al,, 1986). (2) Clr, exhibits on electron micrographs an XMany features of the Cl structure and function are still like structure rather than a linear arrangement of speculative. Perhapsthe above comparisonof the models its domains. may stimulate reading of the original literature and (3) They assign the light chain to one globular further work on this interesting area. domain (catalytic domain) and fragments tl and /I (described by Arlaud et aZ., 1980) to the other globular domain of Clr,, and in analogy to Clr, V. Weiss also in Cls. The dimensions given for the individual Department of Biology domains are in agreement with their known Massachusetts Institute of Technology molecular weights. Cambridge, MA 02139, U.S.A. 437 0022%28361871100437-02
$03.00/O
0
1987 Academic
Press Inc. (London)
Ltd.
438
V. Weiss and J. Engel
J. Engel Abt. fiir Biophysikalische Chemie Biozentrum der Universitlit Base1 Klingelbergstrasse 70, Base1 Switzerland Received 27 October
Poon, P. H., Schumaker, V. N., Phillips, M. L. & &rang, C. J. (1983). J. Mol. Biol. 168, 563-577. Schumaker, V. N., Hanson, D. C., Kilchherr, E., Phillips, M. L. $ Poon, P. H. (1986). Mol. Immunol. 23, 557565. Strang, C. J., Siegel, R. C., Phillips, M. L., Poon, P. H. & Schumaker, V. N. (1982). Proc. Nat. Acad. Sci.,
1986
U.S.A. 79, 586-590. Taniuchi,
Arlaud, G. J., Villiers, C. L., Chesne, S. & Colomb, M. G. (1980). Biochim. Biophys. Acta, 616, 116-129. Colomb, M. G. $ Arlaud, G. J. (1987). J. Mol. Biol. 195, 435. Colomb, M. G., Arlaud, G. J. I% Villiers, C. L. (1984a).
Phil. Tran.s.Roy. Sot. ser.B, 306, 283-292. Colomb, M. G., Ariaud, G. J. & Villiers, Complement, 1, 69-80.
S., Shimada,
S., Mori, Y. t Koyama,
J. (1981).
FEBS Letters, 135, 191-194.
References
C. L. (1984b).
Tschopp, J., Villiger, W., Fuchs, H., Kilchherr, E. & Engel, J. (1980). Proc. Nat. Acud. Sci., U.S.A. 77, 7014-7018. Villiers, C. L., Arlaud, G. J. & Colomb, M. G. (1985). Proc. Nat. Acad. Sci., U.S.A. 82, 4477-4481. Weiss, V., Fauser, C. C Engel, J. (1986). J. Mol. Biol. 189, 573-581.
Edited by H. E. Huxley
Functional
Models of the Cl Complex
Consensus and Disagreement
(4) They postulate an activation mechanism in Maurice Colomb and Gerard Arlaud describe in a which activation of Clr, in Cl is mediated by recent letter (Colomb & Arlaud, 1987) the genesisof interaction between the catalytic domains (light the model and emphasize identical features of their chain domains) of Cls and Clr, thus inducing model and the one proposed by Weiss et al. (1986). enzymatic activity in the Clr zymogen. We would like to add the following comments. In this respect the work of Schumaker and his In a recent publication, which came to our attention after the submission of our paper, Villiers coworkers (Strang et al., 1982; Poon et al., 1983; see et al. (1985) studied the Cls-Clr,-Cls complex by also Schumaker et al., 1986) should also be electron microscopy. The conclusions reached in acknowledged. In their model, which is based on this report differ in important aspects from our the localization of the Cls-Clr,-Cls complex within the Cl complex (near the kink region of Clq) and model. They deduce from their pictures obtained the beads on a string model of Tschopp et al. (1980), with rotary shadowing: (1) A linear arrangement of the domains in Clr,. the Cls-Clr,-Cls complex is folded in an S-like (2) The dimerization of Clr, via the globular manner around the stems of Clq. This arrangement remains essentially unchanged in subsequently (catalytic) domains. refined models. However, those models (Colomb et (3) The assignment of fragment fl (described by 1984aJ; Weiss et al., 1986) describe the al., Arlaud et al (1980)) to -the rod-like domain structure and domain organization of the Cls-Clr*(described as a short polypeptide strand). Cls complex in more detail. These differences are in our view caused mainly On the basis of physicochemical studies of Cls, by the different staining techniques employed by Clr and fragment ClrII, Colomb et al. (1984a,6) both groups. Due to the decoration effect of the propose a model, where the catalytic domains of metal crystals, the rotary shadowing technique Clr, are localized in the center of the Cls-Clr,-Cls gives rise to exaggerated diameters of small complex and those of Cls at the outside. Clr and domains. The negative staining technique, which Cls bind via their interactive domains to each was used in our analysis, is more useful to detect other. In addition they fold the catalytic domains fine structures, especially in globular proteins, and of Cls back to the inside of the cone of Clq to allow small morphological units appear with more for contact of all catalytic domains and thus realistic dimensions. activation of Cl. Thus, the asymmetric X-like structure of Clr, we Weiss et al. (1986) studied the Cls-Clr,-Cls observed, would appear like a croissant-like complex by electron microscopy and demonstrated structure, if heavily shadowed. Similarly from an that Cls is indeed located at both ends of this earphone-like structure (fragment ClrII), or from a chain. On the basis of electron micrographs of Cls, dumb-bell-shaped molecule (Cls) two large globes Clr,, fragment ClrII (previously described by would result. Arlaud et aZ., 1980), the Cls-Clr,-Cls complex and In fact, the molecules observed by Villiers et al. the binding properties of fragment ClrII and a (1985) are extremely large. Clr,, for example, shows fragment of rabbit Cls (Taniuchi et aZ., 1981), they a length of up to 50 nm (Fig. Z(b) of Villiers et al., derived a model for Cl which contains, in addition 1985), which is about the length of the entire Clsto previous models, the following features: Clr,-Cls complex. (1) Cl r and Cl s monomers are described as composed of three domains: two globular domains We acknowledgefully the contributions by Arlaud, separated by a rod-like domain (rather than a thin Colomband their collaborators,to which eight references filament). can be found in our recent publication (Weisset al,, 1986). (2) Clr, exhibits on electron micrographs an XMany features of the Cl structure and function are still like structure rather than a linear arrangement of speculative. Perhapsthe above comparisonof the models its domains. may stimulate reading of the original literature and (3) They assign the light chain to one globular further work on this interesting area. domain (catalytic domain) and fragments tl and /I (described by Arlaud et aZ., 1980) to the other globular domain of Clr,, and in analogy to Clr, V. Weiss also in Cls. The dimensions given for the individual Department of Biology domains are in agreement with their known Massachusetts Institute of Technology molecular weights. Cambridge, MA 02139, U.S.A. 437 0022%28361871100437-02
$03.00/O
0
1987 Academic
Press Inc. (London)
Ltd.
438
V. Weiss and J. Engel
J. Engel Abt. fiir Biophysikalische Chemie Biozentrum der Universitlit Base1 Klingelbergstrasse 70, Base1 Switzerland Received 27 October
Poon, P. H., Schumaker, V. N., Phillips, M. L. & &rang, C. J. (1983). J. Mol. Biol. 168, 563-577. Schumaker, V. N., Hanson, D. C., Kilchherr, E., Phillips, M. L. $ Poon, P. H. (1986). Mol. Immunol. 23, 557565. Strang, C. J., Siegel, R. C., Phillips, M. L., Poon, P. H. & Schumaker, V. N. (1982). Proc. Nat. Acad. Sci.,
1986
U.S.A. 79, 586-590. Taniuchi,
Arlaud, G. J., Villiers, C. L., Chesne, S. & Colomb, M. G. (1980). Biochim. Biophys. Acta, 616, 116-129. Colomb, M. G. $ Arlaud, G. J. (1987). J. Mol. Biol. 195, 435. Colomb, M. G., Arlaud, G. J. I% Villiers, C. L. (1984a).
Phil. Tran.s.Roy. Sot. ser.B, 306, 283-292. Colomb, M. G., Ariaud, G. J. & Villiers, Complement, 1, 69-80.
S., Shimada,
S., Mori, Y. t Koyama,
J. (1981).
FEBS Letters, 135, 191-194.
References
C. L. (1984b).
Tschopp, J., Villiger, W., Fuchs, H., Kilchherr, E. & Engel, J. (1980). Proc. Nat. Acud. Sci., U.S.A. 77, 7014-7018. Villiers, C. L., Arlaud, G. J. & Colomb, M. G. (1985). Proc. Nat. Acad. Sci., U.S.A. 82, 4477-4481. Weiss, V., Fauser, C. C Engel, J. (1986). J. Mol. Biol. 189, 573-581.
Edited by H. E. Huxley