PDBsum entry 3aeh

Hydrolase

PDB id: 3aeh

Contents

Protein chains

277 a.a. *

Waters ×282

* Residue conservation analysis

PDB id:

3aeh

Name:

Hydrolase

Title:

Integral membrane domain of autotransporter hbp

Structure:

Hemoglobin-binding protease hbp autotransporter. Chain: a, b. Fragment: barrel domain. Synonym: hemoglobin-binding protease hbp, hemoglobin-binding protease hbp translocator, helper peptide, hbp, haemoglobin protease. Engineered: yes. Mutation: yes

Source:

Escherichia coli. Organism_taxid: 562. Gene: hbp. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.00Å R-factor: 0.177 R-free: 0.222

Authors:

N.Tajima,S.-Y.Park,J.R.H.Tame

Key ref:

N.Tajima et al. (2010). A novel intein-like autoproteolytic mechanism in autotransporter proteins. J Mol Biol, 402, 645-656. PubMed id: 20615416

Date:

04-Feb-10 Release date: 07-Jul-10

Protein chains

O88093  (HBP_ECOLX) -  Hemoglobin-binding protease hbp autotransporter from Escherichia coli

Seq: 1377 a.a.

Struc: 277 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.3.4.21.- - ?????

J Mol Biol 402:645-656 (2010)

PubMed id: 20615416

A novel intein-like autoproteolytic mechanism in autotransporter proteins.

N.Tajima, F.Kawai, S.Y.Park, J.R.Tame.

ABSTRACT

Many virulence factors secreted by pathogenic Gram negative bacteria are found to be members of the autotransporter protein family. These proteins share a common mechanism by which they exit the periplasm, involving the formation of a 12-stranded beta-barrel domain in the outer membrane. The role of this barrel in secretion of the N-terminal passenger domain is controversial, and no model currently explains satisfactorily the entire body of experimental data. After secretion, some autotransporter barrels auto-proteolytically cleave away the passenger, and one crystal structure is known for a barrel of this type in the postcleavage state. Hbp is an autotransporter of the self-cleaving type, which cuts the polypeptide between two absolutely conserved asparagine residues buried within the barrel lumen. Mutation of the first asparagine residue to isosteric aspartic acid prevents proteolysis. Here we present the crystal structure of a truncated Hbp mutant carrying the C-terminal residues of the passenger domain attached to the barrel. This model mimics the state of the protein immediately prior to separation of the passenger and barrel domains, and shows the role of residues in the so-called "linker" between the passenger and beta domains. This high resolution membrane protein crystal structure also reveals the sites of many water molecules within the barrel. The mechanism of cleavage shows similarities to that of inteins and some viral proteins, but with a novel means of promoting nucleophilic attack.