PDBsum entry 1ioc

Hydrolase

PDB id: 1ioc

Contents

Protein chain

133 a.a. *

Metals

_NA ×3

Waters ×88

* Residue conservation analysis

PDB id:

1ioc

Name:

Hydrolase

Title:

Crystal structure of mutant human lysozyme, eaea-i56t

Structure:

LysozymE C. Chain: a. Engineered: yes. Mutation: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Expressed in: pichia pastoris. Expression_system_taxid: 4922.

Resolution:

2.40Å R-factor: 0.210

Authors:

S.Goda,K.Takano,Y.Yamagata,K.Yutani

Key ref:

S.Goda et al. (2002). Elongation in a beta-structure promotes amyloid-like fibril formation of human lysozyme. J Biochem (tokyo), 132, 655-661. PubMed id: 12359083

Date:

27-Feb-01 Release date: 09-Oct-02

Protein chain

P61626  (LYSC_HUMAN) -  Lysozyme C from Homo sapiens

Seq: 148 a.a.

Struc: 133 a.a.*

* PDB and UniProt seqs differ at 4 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.3.2.1.17 - lysozyme.
• Reaction: Hydrolysis of the 1,4-beta-linkages between N-acetyl-D-glucosamine and N-acetylmuramic acid in peptidoglycan heteropolymers of the prokaryotes cell walls.

J Biochem (tokyo) 132:655-661 (2002)

PubMed id: 12359083

Elongation in a beta-structure promotes amyloid-like fibril formation of human lysozyme.

S.Goda, K.Takano, Y.Yamagata, S.Maki, K.Namba, K.Yutani.

ABSTRACT

To understand the mechanism of amyloid fibril formation of a protein, we examined wild-type and three mutant human lysozymes containing both amyloidogenic and non-amyloidogenic proteins: I56T (amyloidogenic); EAEA, which has four additional residues (Glu-Ala-Glu-Ala-) at the N-terminus located on a beta-structure; and EAEA-I56T, which is an I56T mutant of EAEA. All formed amyloid-like fibrils through an in the increase contents of alpha-helix with increasing concentration of ethanol. The order of propensity for amyloid-like fibril formation in highly concentrated ethanol solution is EAEA-I56T > EAEA > I56T > wild-type. This order is almost the reverse of the order of conformational stability of these proteins, wild-type > EAEA > I56T > EAEA-I56T. The important views in this work are as follows. (i) Artificially modified proteins formed amyloid fibrils in vitro. This means that amyloid formation is a generic property of polypeptide chains. (ii) The amyloidogenic mutation Ile56 to Thr caused the destabilization and promoted fibril formation in the wild-type and EAEA human lysozymes, indicating that instability facilitates amyloid formation. (iii) The mutant protein EAEA human lysozyme had higher propensity for fibril formation than the amyloidogenic mutant protein, indicating that amyloid formation is controlled not only by stability but also by other factors. In this case, appending polypeptide chains to a beta-structure accelerated amyloid formation.