PDBsum entry 1jft

Transcription/DNA

PDB id: 1jft

Contents

Protein chain

340 a.a. *

DNA/RNA

Ligands

PO4

HPA

Waters ×65

* Residue conservation analysis

PDB id:

1jft

Name:

Transcription/DNA

Title:

Purine repressor mutant-hypoxanthine-purf operator complex

Structure:

5'-d( Tp Ap Cp Gp Cp Ap Ap Ap Cp Gp Tp Tp Tp Gp Cp Gp T)- 3'. Chain: b. Engineered: yes. Purine nucleotide synthesis repressor. Chain: a. Engineered: yes. Mutation: yes

Source:

Synthetic: yes. Escherichia coli. Organism_taxid: 562. Gene: purr. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Tetramer (from PDB file)

Resolution:

2.50Å R-factor: 0.192

Authors:

J.L.Huffman,F.Lu,H.Zalkin,R.G.Brennan

Key ref:

J.L.Huffman et al. (2002). Role of residue 147 in the gene regulatory function of the Escherichia coli purine repressor. Biochemistry, 41, 511-520. PubMed id: 11781089 DOI: 10.1021/bi0156660

Date:

21-Jun-01 Release date: 08-Feb-02

Protein chain

P0ACP7  (PURR_ECOLI) -  HTH-type transcriptional repressor PurR from Escherichia coli (strain K12)

Seq: 341 a.a.

Struc: 340 a.a.*

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

DNA/RNA chain

T-A-C-G-C-A-A-A-C-G-T-T-T-G-C-G-T 17 bases

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1021/bi0156660

Biochemistry 41:511-520 (2002)

PubMed id: 11781089

Role of residue 147 in the gene regulatory function of the Escherichia coli purine repressor.

J.L.Huffman, F.Lu, H.Zalkin, R.G.Brennan.

ABSTRACT

The crystal structures of corepressor-bound and free Escherichia coli purine repressor (PurR) have delineated the roles of several residues in corepressor binding and specificity and the intramolecular signal transduction (allosterism) of this LacI/GalR family member. From these structures, residue W147 was implicated as a key component of the allosteric response, but in many members of the LacI/GalR family, position 147 is occupied by an arginine. To understand the role of this tryptophan at position 147, three proteins, substituted by phenylalanine (W147F), alanine (W147A), or arginine (W147R), were constructed and characterized in vivo and in vitro, and their structures were determined. W147F displays a decreased affinity for corepressor and is a poor repressor in vivo. W147A and W147R, on the other hand, are super repressors and bind corepressor 13.6 and 7.9 times more tightly, respectively, than wild-type. Each mutant PurR-hypoxanthine-purF operator holo complex crystallizes isomorphously to wild-type. Whereas the apo corepressor binding domain (CBD) of W147F crystallizes under those conditions used for the wild-type protein, neither the apo CBD of W147R nor W147A crystallizes, although screened extensively for new crystal forms. Structures of the holo repressor mutants have been solved to resolutions between 2.5 and 2.9 A, and the structure of the apo CBD of W147F has been solved to 2.4 A resolution. These structures provide insight into the altered biochemical properties and physiological functions of these mutants, which appear to depend on the sometimes subtle preference for one conformation (apo vs holo) over the other.