Yasuhiro Ozeki. Department of System Element, Faculty of Science, Yokohama City University, 22-2, Seto, Kanazawaku, Yokohama 236, Japan

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1 Vol. 41, No. 3, March 1997 Pages PURIFICATION OF A 63 kda I~-D-GALACTOSIDE BINDING LECTIN FROM CUTTLEFISH, Todarodes pacificus. Yasuhiro Ozeki Department of System Element, Faculty of Science, Yokohama City University, 22-2, Seto, Kanazawaku, Yokohama 236, Japan Received November 30, 1996 Received after revision December 24, 1996 Summary: A 13-D-galactoside binding lectin (TPL) was newly purified from the body walls of the cuttlefish,todarodes pacificus with lactosyl-agarose affinity column chromatography and reversed-phase HPLC. Many of the biological properties of the lectin were similar to those of the representative animal I~-D-galactoside binding lectin, "galectin". However, with a molecular mass of 63 kda under reducing and non-reducing conditions on SDS-PAGE, TPL is larger than any previously reported galectins. The native molecular mass of TPL was estimated to be about 60 kda by gel filtration, suggesting that it exists as a monomer and that a single polypeptide containing at least two sugar binding sites. The antisera raised against TPL did not crossreact with bull frog egg galectin-1, suggesting that TPL is immunologically distinct from the lower vertebrate galectin. Key words: Lectin, 13-Galactoside binding, Cuttlefish, Galectin. INTRODUCTION 13-D-Galactoside binding lectins which do not require divalent cation for their activity are widely distributed, from cytoplasms to extracellular matrices, in many animal organs [1]. Many show a molecular mass of 14 or kda and contain the conservative amino acid sequence. Since several isotypes have been detected from various sources, these lectins have been classified as the "galectin super family" [2]. Although a lot is known about the structure of members of this family, little is known as to their physiological role. Recently, it was reported that some galectins display potent /97/ /0 Copyright by Academic Press Australia. 633 All rights of reproduction in any form reserved.

2 functions such as tumor growth [3], cell adhesion [4,5], or induction of programed cell death [6], suggesting that the lectins are multi-functional which act for the several important biological phenomena. Furthermore, 13-galactoside binding lectins purified from nematoda [7,8] and sponge [9] respectively, showed about less than 30 % amino acid sequence homology with vertebrate galectin. These results suggest that several unknown types of 13-galactoside binding lectins, distinct from vertebrate galectin, exist in invertebrates. In this study, the author purified a 13-galactoside binding lectin from cuttlefish and elucidated it as a new 13-galactoside binding lectin with larger molecular mass (63 kda) than any previously reported galectin. MATERIALS AND METHODS Materials: Cuttlefish, Todarodes pacificus was purchased commercially from a local fish market. Purification of lectin: The body wall obtained from the cuttlefish was homogenized with 10 vols (WN) of 150 mm NaCI containing 20 mm Tris-HCI, ph 7.5 (Tris-buffered saline [TBS]), 2 mm 13-mercaptoethanol and 10 mm EDTA (buffer A). The precipitate obtained from centrifugation at 27,500xg for 1 h at 4 oc was resuspended with 3 vols of TBS containing 100 mm lactose (buffer B) and incubated at 4 oc overnight. The supernatant obtained by further centrifugation was extensively dialyzed against 100 mm NaHCO3. After centrifugation at 27,500xg for 1 h, the supernatant was applied to a lactosyl-agarose column (1.0x4.0 cm, Seikagaku Kogyo, Tokyo, Japan). The column was washed with buffer A until the absorbance at 280 nm reached the baseline. The fraction containing lectin was eluted with buffer B from the column. For further purification of the lectin, the collected fraction was subjected to reversed-phase HPLC. on a Aquapore RP-300 column (100x4.6 mm, Applied Biosystems, CA, USA) with gradients of acetonitrile in diluted aqueous trifluoroacetic acid [10]. The peak fraction was collected and concentrated with a Centrifugal concentrator CC-105 (Tomy-Seiko, Tokyo, Japan). Analytical methods: The protein concentration was estimated by the method of Lowry et al. [11]. A hemagglutination assay was performed using trypsinized and glutaraldehyde-fixed rabbit erythrocytes [12]. Apparent molecular mass was estimated by gel filtration on a column packed with Sepharose CL-6B (1.0x90 cm, Pharmacia, Uppsala, Sweden) equilibrated with TBS and by S DS-PAGE [13] with 10 % separation gel. Antiserum against TPL was raised in rabbits by repeated injection (totally 1 mg) of 634

3 purified TPL emulsified with Freund's aduvant (Wako Pure Chemicals, Tokyo, Japan). TPL and bull frog (Rana catesbeiana) egg galectin-1 (RCEGL-1) [14] were subjected to SDS-PAGE followed by electroblotting onto an Immobilon P membrane (Milipore, Bedford, MA, USA) [15]. The western blotting with anti-tpl and anti-rcegl-1 sera was performed as described previously [5]. RESULTS AND DISCUSSION TBS-extracts obtained from cuttlefish body wall exhibited little hemagglutinating activity against rabbit erythrocytes (data not shown). However, the extensively dialyzed crude extract solubilized with TBS containing 0.1M lactose, agglutinated the erythrocytes. Since the activity appeared in the extract after homogenizing with the buffer containing haptenic sugar (lactose), it seemed that the lectin present among the tissue bound with the endogenous ligand(s) on the tissue. The hemagglutinating activity of the extract was inhibited in the presence of lactose. The cuttlefish, T. pacificus lectin (TPL) was purified from the crude extract using lactose-conjugated agarose column affinity chromatography (Fig. 1A) and RP-HPLC (data not shown). TPL appeared as a band of 63 kda on SDS-PAGE and the profile did not change between reducing and non-reducing conditions (Fig. 1B, column +2ME vs. -2ME), indicating that these lectins were not disulfied-linked multimers. TPL was eluted at a molecular mass of about 60 kda by gel filtration on a Sepharose CL-6B column and the peak fraction was confirmed to hold the hemagglutinating activity (Fig. 2). A summary of the purification of the TPL is shown in Table I. In a typical purification experiment, about 0.2 mg of TPL was purified from 100 g of body wall. The saccharide specificity of TPL is summarized in Table I1. The hemagglutinating activity of TPL was specifically inhibited by the addition of the I]-D-galactosides. Thiodigalactoside was the most potent inhibitor followed by lactose. However, c~-d-galactosides such as methyl-~-d-galactoside and melibiose little inhibited TPL induced hemagglutinating 635

4 BIOCHEMISTRYond MOLECULAR BIOLOGY INTERNATIONAL A= 1.5 B. kda +2ME -2ME kda A 1.0" '~' F-- a'o 4b so FRACTION NUMBER Figure 1. Affinity purification and SDS-PAGE pattern of TPL. A: Lactose extracts of the body wall of cuttlefish was applied to a lactosyl-agarose column equilibrated with MTBS after extensive dialysis. B: Purified TPL was subjected to S DS-PAGE under reducing (+2ME)and non-reducing (-2ME)conditions. Numbers at left indicate molecular masses of marker proteins: phosphorylase b (97 kda), bovine serum albumin (66 kda), aldolase (42 kda), carbonic anhydrase (30 kda), trypsin inhibiter (20 kda), and lysozyme (14 kda). F designates the gel front. activity. TPL was detected not only in the body wall but also from TBS containing 100 mm lactose extracts of leg and mantle of cuttlefish, by western blotting analysis using anti-tpl rabbit serum. Little signal was detected from internal organs (data not shown). TBS containing 100 mm lactose extracts from mantle and legs showed hemagglutinating activity which was inhibited with 13-galactoside sugar as purified TPL (data not shown), suggesting that TPL also localizes in these tissues. The antisera against TPL and RCEGL-1 did not crossreact with the RCEGL-1 and TPL antigens, respectively (Fig. 3). In this study, we elucidated the presence of a divalent cation non-required-type 16-galactoside binding lectin in cepharopodis tissue. Lectins with this property are 636

5 I I I I A I v E= o.~ 4 ~ i I I-- i ~ i ', i FRACTION NUMBER Figure 2. Estimation of native molecular mass. TPL was subjected to gel filtration using a Sepharose CL-6B column (1.0 x 90 cm). TPL was eluted as a single peak corresponding to the molecular mass of about 60 kda. Arrows indicate elution position of marker protein: amylase (200 kda) (1), alcohol dehydrogenase (150 kda) (2), bovine serum albumin (66 kda) (3), and carbonic anhydrase (29 kda) (4) were used as molecular mass standard markers. Bar means titer of hemagglutinating activity. Table I. Purif~a~on of TPL. TIB Protein Volume Total Specilic Recovery (rng/ml) (ml) aclmty* aclm~y. ** (%) Crude extactjon , Pudlied TPL ,144 6, *Total ac~vity;t~r x Volume. **Spec~ aclivity;, -Iiter/rngof pro'ein. reported to have a molecular mass of kda and a structural motif known as the "galectin super family". TPL has properties in common with the galectin super family such as sugar binding, solubility by the haptenic sugar from tissues, and localization at the tissue as muscle (as body wall, legs, and mantle), however the molecular mass of the polypeptide was larger (63 kda) than that of any previously reported galectins. By gel filtration of TPL, it appeared that the protein exists as a monomer in buffer, 637

6 Table II. E~3tsofSaocharidesonTPL Induced Hemagglulina~on. Saccharide ooncenlration (mm) Thiodigalact3slde 0.2 Lactose 0.4 Melhyt 13-D-galachopyranoslde 0.8 Me~yl c~-dgajac~pyranoslde 3.1 Melibiose 25.0 Sucrose >500 DGalacl3se 6B N-Acetyl-D-galact3samine 50.0 N-AcetyI-D-gluoosamine >50.0 D-Mannose >50.0 D-Gluoose >50.0 L-Fucose >50.0 LeclJn l~erwas previously adjusled t316. Tn~nized and glutaraldehyde-ixed rabbiten2~rocyteswere used brlhe assay. CBB anti-tpl anlj-rcegl-1 TPL RCEGL-1 Figure 3. Immunoblotting of TPL. Five micrograms each of TPL and RCEGL-1 [14] was transferred to a Immobilon P membrane membrane after SDS-PAGE Each column was stained with coomassie brilliant blue R-250 (CBB), anti-tpl serum (anti-tpl), or anti-rcegl-1 serum (anti-rcegl-1) [5]. 638

7 suggesting the presence of multi-sugar binding sites. The 3-D structures of TPL and galectin-1 of lower vertebrate (RCEGL-1) seem to be distinctive, since no immunocrosreactivity occurred between them. Thus, TPL seems to be a lectin with unique characters. Further analysis of.the amino acid sequence of TPL will elucidate more useful structural and functional information as to whether the lectin belongs to a new species in the galectin family or is a novel molecule with a new structural motif. Acknowledgments This work was supported in part by Grants-in-Aid from Yokohama City University. REFERENCES 1. Barondes, S. H. (1986) The Lectins: Properties, Functions and Applications in Biology and Medicine. pp , (Liener, I. E., Sharon. N., and Goldstein, I.J., Eds.) Academic Press, San Diego. 2. Barondes, S. H., Cooper, D. N. W., Gitt, M. A., and Leffler, H. (1994) J. Biol. Chem. 269, Yamaoka, K., Ohno, S., Kawasaki, H., and Suzuki, K. (1991) Biochem. Biophys. Res. Commun. 179, Ozeki, Y., Matsui, T., and Titani, K. (1991) FEBS Lett. 289, Ozeki, Y., Matsui, T., Yamamoto, Y., Funahashi, M., Hamako, J., and Titani, K. (1995) Glycobiology 5, Perillo, N. L., Pace, K. E., Seilhamer, J. J., and Baum L. G. (1995) Nature 378, Hirabayashi, J., Satoh, M., and Kasai, K (1992) J. Biol. Chem. 267, Hirabayashi, J., Ubukata, T. and Kasai, K (1996) J. Biol. Chem_ 271, Pfeifer, K., Haasemann, M., Gamulin, V., Bretting, H, Fahrenholz, F., and Muller, W. E. G. (1993) Glycobiology 3, Mahoney, W. C. and Hermodson, M. A. (1980) J. Biol. Chem. 255, Lowry, O. H., Rosebrough, N. J., Farr, A. L. and Randall, R.J. (1951) J. Biol. Chem. 193, Matsui, T. (1984) Biol. Bull. 166, Laemmli U. K. (1970) Nature 227,

8 14. Ozeki, Y., Matsui, T., Nitta, K., Kawauchi, H., Takayanagi, Y. and Titani, K. (1991) Biochem Biophys. Res. Commun. 178, Matsudaira, P. (1987) J. Biol. Chem. 262,