PDBsum entry 2zpc

Protein transport

PDB id: 2zpc

Contents

Protein chain

183 a.a. *

Waters ×5

* Residue conservation analysis

PDB id:

2zpc

Name:

Protein transport

Title:

Crystal structure of the r43l mutant of lola in the closed form

Structure:

Outer-membrane lipoprotein carrier protein. Chain: a. Synonym: p20. Engineered: yes. Mutation: yes

Source:

Escherichia coli. Organism_taxid: 83333. Gene: lola, lpla, yzzv, b0891, jw0874. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.35Å R-factor: 0.241 R-free: 0.275

Authors:

K.Takeda,N.Yokota,Y.Oguchi,H.Tokuda,K.Miki

Key ref:

Y.Oguchi et al. (2008). Opening and closing of the hydrophobic cavity of LolA coupled to lipoprotein binding and release. J Biol Chem, 283, 25414-25420. PubMed id: 18617521 DOI: 10.1074/jbc.M804736200

Date:

10-Jul-08 Release date: 05-Aug-08

Protein chain

P61316  (LOLA_ECOLI) -  Outer-membrane lipoprotein carrier protein from Escherichia coli (strain K12)

Seq: 203 a.a.

Struc: 183 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1074/jbc.M804736200

J Biol Chem 283:25414-25420 (2008)

PubMed id: 18617521

Opening and closing of the hydrophobic cavity of LolA coupled to lipoprotein binding and release.

Y.Oguchi, K.Takeda, S.Watanabe, N.Yokota, K.Miki, H.Tokuda.

ABSTRACT

Outer membrane-specific lipoproteins of Escherichia coli are released from the inner membrane through the action of Lol-CDE, which leads to the formation of a complex between the lipoprotein and LolA, a periplasmic chaperone. LolA then transfers lipoproteins to LolB, a receptor in the outer membrane. The structures of LolA and LolB are very similar, having an incomplete beta-barrel covered with an alpha-helical lid forming a hydrophobic cavity inside. The cavity of LolA, but not that of LolB, is closed and thus inaccessible to the bulk solvent. Previous studies suggested that Arg at position 43 of LolA is critical for maintaining this closed structure. We show here, through a crystallographic study, that the cavity of the LolA(R43L) mutant, in which Leu replaces Arg-43, is indeed open to the external milieu. We then found that the binding of a fluorescence probe distinguishes the open/close state of the cavity. Furthermore, it was revealed that the hydrophobic cavity of LolA opens upon the binding of lipoproteins. Such a liganded LolA was found to be inactive in the release of lipoproteins from the inner membrane. On the other hand, the liganded LolA became fully functional when lipoproteins were removed from LolA by detergent treatment or transferred to LolB. Free LolA thus formed was inaccessible to a fluorescence probe. These results, taken together, reveal the LolA cycle, in which the hydrophobic cavity undergoes opening and closing upon the binding and release of lipoproteins, respectively.

Selected figure(s)

Figure 1.
FIGURE 1. Crystal structure of LolA(R43L). Composite omit maps of LolA(R43L) in the trigonal crystal form (A) and monoclinic crystal form (B) contoured at the 1.0 level. C, structures of the open (monoclinic crystal, colored) and closed (trigonal crystal, gray) forms of LolA(R43L) are superimposed. D, a view rotated by 90° from C around the horizontal axis. E, the positional deviations of C atoms between the open and closed structures. Red and orange belts, respectively, indicate helical regions and loop 8–9, which deviate significantly.

Figure 2.
FIGURE 2. Open/close state of the hydrophobic cavity of LolA(R43L). The hydrophobic cavities of the closed (A) and open (B) forms of LolA(R43L) are drawn as gray globules. The strands forming the molecular framework are shown in gray. The proved radius is 1.4 Å. The side chain of mutated Leu-43 is shown in red. Stick models in green show aromatic residues located around the entrance to the cavity. C and D, stereoscopic views around position 43 of the trigonal crystal form (C) and monoclinic crystal form (D) are shown. The substituted Leu-43 and neighboring Pro44 form a cis-type peptide bond like those in wild-type LolA in both forms.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2008, 283, 25414-25420) copyright 2008.

Figures were selected by an automated process.