STRUCTURE OF RICIN B-CHAIN AT 2.5-A RESOLUTION

被引:282
作者
RUTENBER, E [1 ]
ROBERTUS, JD [1 ]
机构
[1] UNIV TEXAS,CLAYTON FDN BIOCHEM INST,DEPT CHEM & BIOCHEM,AUSTIN,TX 78712
来源
PROTEINS-STRUCTURE FUNCTION AND GENETICS | 1991年 / 10卷 / 03期
关键词
RICIN TOXIN; B-CHAIN; GALACTOSE BINDING; MOLECULAR EVOLUTION;
D O I
10.1002/prot.340100310
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The heterodimeric plant toxin ricin has been refined to 2.5 angstrom resolution. The B-chain lectin (RTB) is described in detail. The protein has two major domains, each of which has a galactose binding site. RTB has no regular secondary structure but displays several OMEGA loops. Each RTB domain is made of three copies of a primitive 40 residue folding unit, which pack around a pseudo threefold axis. In each domain, galactose binds in a shallow cleft formed by a three residue peptide kink on the bottom and an aromatic ring on the top. At the back of the cleft, an aspartate forms hydrogen bonds to the C3 and C4 hydroxyls of galactose, whereas a glutamine bonds to the C4 alcohol, helping to define specific epimer binding. In addition to analyzing the sugar binding mechanism, the assembly of subdomain units around the pseudo threefold axis of each domain is described. The subdomains contribute conserved Trp, Leu, and Ile residues to a compact central hydrophobic core. This tight threefold binding probably drives the peptide folding and stabilizes the protein structure.
引用
收藏
页码:260 / 269
页数:10
相关论文
共 26 条
[1]  
BAENZIGER JU, 1979, J BIOL CHEM, V254, P9795
[2]   AROMATIC-AROMATIC INTERACTION - A MECHANISM OF PROTEIN-STRUCTURE STABILIZATION [J].
BURLEY, SK ;
PETSKO, GA .
SCIENCE, 1985, 229 (4708) :23-28
[3]  
EINSPAHR H, IN PRESS T AM CRYST, V25
[4]   IDENTIFICATION OF THE TRYPTOPHAN RESIDUE LOCATED AT THE LOW-AFFINITY SACCHARIDE BINDING-SITE OF RICIN-D [J].
HATAKEYAMA, T ;
YAMASAKI, N ;
FUNATSU, G .
JOURNAL OF BIOCHEMISTRY, 1986, 100 (03) :781-788
[5]  
HOUSTON LL, 1982, J BIOL CHEM, V257, P4147
[6]  
JOHNSON VG, IN PRESS INTRACELLUL
[7]  
JONES TA, 1982, COMPUTATIONAL CRYSTA, P303
[8]   STRUCTURE OF RICIN A-CHAIN AT 2.5-A [J].
KATZIN, BJ ;
COLLINS, EJ ;
ROBERTUS, JD .
PROTEINS-STRUCTURE FUNCTION AND GENETICS, 1991, 10 (03) :251-259
[9]   STRUCTURES OF SUGAR CHAINS OF RICIN-D [J].
KIMURA, Y ;
HASE, S ;
KOBAYASHI, Y ;
KYOGOKU, Y ;
IKENAKA, T ;
FUNATSU, G .
JOURNAL OF BIOCHEMISTRY, 1988, 103 (06) :944-949
[10]   LOOPS IN GLOBULAR-PROTEINS - A NOVEL CATEGORY OF SECONDARY STRUCTURE [J].
LESZCZYNSKI, JF ;
ROSE, GD .
SCIENCE, 1986, 234 (4778) :849-855