PDBsum entry 4hlu

Hydrolase

PDB id: 4hlu

Contents

Protein chains

265 a.a.

245 a.a.

Ligands

ADP ×4

ACT ×5

Waters ×89

PDB id:

4hlu

Name:

Hydrolase

Title:

Structure of the ecfa-a' heterodimer bound to adp

Structure:

Putative abc transporter atp-binding protein tm_0222. Chain: a, b. Engineered: yes. Energy-coupling factor transporter atp-binding protein ecfa. Chain: d, c. Synonym: ecf transporter a component ecfa. Engineered: yes. Mutation: yes

Source:

Thermotoga maritima. Organism_taxid: 243274. Strain: msb8. Gene: tm0222, tm_0222. Expressed in: escherichia coli. Expression_system_taxid: 469008. Gene: cbio, ecfa, tm1663, tm_1663.

Resolution:

2.70Å R-factor: 0.216 R-free: 0.258

Authors:

D.N.Wang,N.K.Karpowich

Key ref:

N.K.Karpowich and D.N.Wang (2013). Assembly and mechanism of a group II ECF transporter. Proc Natl Acad Sci U S A, 110, 2534-2539. PubMed id: 23359690

Date:

17-Oct-12 Release date: 06-Feb-13

Protein chains

Q9WY65  (ECFA2_THEMA) -  Energy-coupling factor transporter ATP-binding protein EcfA2 from Thermotoga maritima (strain ATCC 43589 / DSM 3109 / JCM 10099 / NBRC 100826 / MSB8)

Seq: 266 a.a.

Struc: 265 a.a.*

Protein chains

Q9X1Z1  (ECFA1_THEMA) -  Energy-coupling factor transporter ATP-binding protein EcfA1 from Thermotoga maritima (strain ATCC 43589 / DSM 3109 / JCM 10099 / NBRC 100826 / MSB8)

Seq: 259 a.a.

Struc: 245 a.a.*

* PDB and UniProt seqs differ at 11 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chains A, D, B, C: E.C.7.-.-.-

Proc Natl Acad Sci U S A 110:2534-2539 (2013)

PubMed id: 23359690

Assembly and mechanism of a group II ECF transporter.

N.K.Karpowich, D.N.Wang.

ABSTRACT

Energy-coupling factor (ECF) transporters are a recently discovered family of primary active transporters for micronutrients and vitamins, such as biotin, thiamine, and riboflavin. Found exclusively in archaea and bacteria, including the human pathogens Listeria, Streptococcus, and Staphylococcus, ECF transporters may be the only means of vitamin acquisition in these organisms. The subunit composition of ECF transporters is similar to that of ATP binding cassette (ABC) importers, whereby both systems share two homologous ATPase subunits (A and A'), a high affinity substrate-binding subunit (S), and a transmembrane coupling subunit (T). However, the S subunit of ECF transporters is an integral membrane protein, and the transmembrane coupling subunits do not share an obvious sequence homology between the two transporter families. Moreover, the subunit stoichiometry of ECF transporters is controversial, and the detailed molecular interactions between subunits and the conformational changes during substrate translocation are unknown. We have characterized the ECF transporters from Thermotoga maritima and Streptococcus thermophilus. Our data suggests a subunit stoichiometry of 2S:2T:1A:1A' and that S subunits for different substrates can be incorporated into the same transporter complex simultaneously. In the first crystal structure of the A-A' heterodimer, each subunit contains a novel motif called the Q-helix that plays a key role in subunit coupling with the T subunits. Taken together, these findings suggest a mechanism for coupling ATP binding and hydrolysis to transmembrane transport by ECF transporters.