PDBsum entry 1exs

Lipid binding protein

PDB id: 1exs

Contents

Protein chain

160 a.a. *

Ligands

GOL

Metals

_NA

Waters ×154

* Residue conservation analysis

PDB id:

1exs

Name:

Lipid binding protein

Title:

Structure of porcine beta-lactoglobulin

Structure:

Beta-lactoglobulin. Chain: a. Fragment: variant 1a. Other_details: a putative but biologically functional dimer is created by the crystallographic 2-fold axis

Source:

Sus scrofa. Pig. Organism_taxid: 9823. Secretion: milk

Biol. unit:

Dimer (from PDB file)

Resolution:

2.39Å R-factor: 0.219 R-free: 0.282

Authors:

J.P.Abrahams,F.J.Hoedemaeker

Key ref:

F.J.Hoedemaeker et al. (2002). A novel pH-dependent dimerization motif in beta-lactoglobulin from pig (Sus scrofa). Acta Crystallogr D Biol Crystallogr, 58, 480-486. PubMed id: 11856834 DOI: 10.1107/S0907444902000616

Date:

04-May-00 Release date: 15-Nov-00

Protein chain

P04119  (LACB_PIG) -  Beta-lactoglobulin-1A/1C from Sus scrofa

Seq: 178 a.a.

Struc: 160 a.a.

DOI no: 10.1107/S0907444902000616

Acta Crystallogr D Biol Crystallogr 58:480-486 (2002)

PubMed id: 11856834

A novel pH-dependent dimerization motif in beta-lactoglobulin from pig (Sus scrofa).

F.J.Hoedemaeker, R.W.Visschers, A.C.Alting, K.G.de Kruif, M.E.Kuil, J.P.Abrahams.

ABSTRACT

beta-Lactoglobulin (BLG) is a lipocalin and is the major protein in the whey of the milk of cows and other ruminants, but not in all mammalian species. The biological function of BLG is not clear, but a potential role in carrying fatty acids through the digestive tract has been proposed. The capability of BLG to aggregate and form gels is often used to thicken foodstuffs. The structure of the porcine form is sufficiently different from other known BLG structures that SIRAS phases had to be measured in order to solve the crystal structure to 2.4 A resolution. The r.m.s. deviation of C(alpha) atoms is 2.8 A between porcine and bovine BLG. Nevertheless, the typical lipocalin fold is conserved. Compared with bovine BLG, the tilted alpha-helix alters the arrangement of surface residues of the porcine form, completely changing the dimerization behaviour. Through a unique pH-dependent domain-swapping mechanism involving the first ten residues, a novel dimer interface is formed at the N-terminus of porcine BLG. The existence of this novel dimer at low pH is supported by gel-filtration experiments. These results provide a rationale for the difference in physicochemical behaviour between bovine and porcine BLG and point the way towards engineering such dimerization motifs into other members of the lipocalin family.

Selected figure(s)

Figure 3.
Figure 3 (Divergent) stereo image of the dimer interface. Residues forming side-chain interactions, as well as residues 1 and 13, are labelled. This figure was produced with SETOR (Evans, 1993[Evans, S. V. (1993). J. Mol. Graph. 11, 134-138.]) [199][Figure 4]

Figure 4.
Figure 4 Different (putative) dimeric forms of lipocalins. Disulfide bridges are indicated in yellow; free cysteines are indicated in green. The dimers were automatically generated from the original PDB entries by the PQS server ([201]http://pqs.ebi.ac.uk ). (a) Bovine odorant-binding protein ([202]1obp ; Tegoni et al., 1996[203] [Tegoni, M., Ramoni, R., Bignetti, E., Spinelli, S. & Cambillau, C. (1996). Nature Struct. Biol. 3, 863-867.]-[204][bluearr.gif] ), buried surface area 2399.7 Å2. (b) Porcine BLG ([205]1exs ; this paper), buried surface area 1757.7 Å2. (c) Major horse allergen (1ew3; Lascombe et al., 2000[206] [Lascombe, M. B., Gregoire, C., Poncet, P., Tavares, G. A., Rosinski-Chupin, I., Rabillon, J., Goubran-Botros, H., Mazie, J. C., David, B. & Alzari, P. M. (2000). J. Biol. Chem. 275, 21572-21577.]-[207][bluearr.gif] ), buried surface area 1023.3 Å2. (d) Porcine odorant-binding protein ([208]1e06 ; Spinelli et al., 1998[209] [Spinelli, S., Ramoni, R., Grolli, S., Bonicel, J., Cambillau, C. & Tegoni, M. (1998). Biochemistry, 37, 7913-7918.]-[210][bluearr.gif] ), buried surface area 848.2 Å2. (e) Nitrophorin 4 ([211]1eqd ; Weichsel et al., 2000[212] [Weichsel, A., Andersen, J. F., Roberts, S. A. & Montfort, W. R. (2000). Nature Struct. Biol. 7, 551-554.]-[213][bluearr.gif] ), buried surface area 789.1 Å2. (f) Bovine BLG ([214]1b0o ; Wu et al., 1999[215] [Wu, S. Y., Perez, M. D., Puyol, P. & Sawyer, L. (1999). J. Biol. Chem. 274, 170-174.]-[216][bluearr.gif] ), buried surface area 484.1 Å2. The figure was produced with Weblab Viewer Lite (MSI).

The above figures are reprinted by permission from the IUCr: Acta Crystallogr D Biol Crystallogr (2002, 58, 480-486) copyright 2002.

Figures were selected by an automated process.