PDBsum entry 2a37

Signaling protein

PDB id: 2a37

Contents

Protein chain

59 a.a. *

* Residue conservation analysis

PDB id:

2a37

Name:

Signaling protein

Title:

Solution structure of the t22g mutant of n-terminal sh3 domain of drk (drkn sh3 domain)

Structure:

Protein e(sev)2b. Chain: a. Fragment: n-terminal sh3 domain, residues 1-59. Synonym: protein enhancer of sevenless 2b, sh2-sh3 adapter protein drk, downstream of receptor kinase. Engineered: yes. Mutation: yes

Source:

Drosophila melanogaster. Fruit fly. Organism_taxid: 7227. Gene: drk, e(sev)2b, cg6033. Expressed in: escherichia coli. Expression_system_taxid: 562.

NMR struc:

10 models

Authors:

I.Bezsonova,A.Singer,W.-Y.Choy,M.Tollinger,J.D.Forman-Kay

Key ref:

I.Bezsonova et al. (2005). Structural comparison of the unstable drkN SH3 domain and a stable mutant. Biochemistry, 44, 15550-15560. PubMed id: 16300404 DOI: 10.1021/bi0512795

Date:

23-Jun-05 Release date: 13-Dec-05

Protein chain

Q08012  (DRK_DROME) -  Growth factor receptor-bound protein 2 from Drosophila melanogaster

Seq: 211 a.a.

Struc: 59 a.a.*

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

DOI no: 10.1021/bi0512795

Biochemistry 44:15550-15560 (2005)

PubMed id: 16300404

Structural comparison of the unstable drkN SH3 domain and a stable mutant.

I.Bezsonova, A.Singer, W.Y.Choy, M.Tollinger, J.D.Forman-Kay.

ABSTRACT

The N-terminal SH3 domain of the Drosophila adapter protein Drk (drkN SH3 domain) is marginally stable (DeltaG(U) = 1 kcal/mol) and exists in equilibrium between folded and highly populated unfolded states. The single substitution T22G, however, completely stabilizes the protein (DeltaG(U) = 4.0 kcal/mol). To probe the causes of instability of the wild-type (WT) protein and the dramatic stabilization of the mutant, we determined and compared nuclear magnetic resonance structures of the folded WT and mutant drkN SH3 domains. Residual dipolar coupling (RDC) and carbonyl chemical-shift anisotropy (C'-CSA) restraints measured for the WT and T22G domains were used for calculating the structures. The structures for the WT and mutant are highly similar. Thr22 of the WT and Gly22 of the mutant are at the i + 2 position of the diverging, type-II beta-turn. Interestingly, not only Gly22 but also Thr22 successfully adopt an alpha(L) conformation, required at this position of the turn, despite the fact that positive phi values are energetically unfavorable and normally disallowed for threonine residues. Forcing the Thr22 residue into this unnatural conformation increases the free energy of the folded state of the WT domain relative to its T22G mutant. Evidence for residual helix formation in the diverging turn region has been previously reported for the unfolded state of the WT drkN SH3 domain, and this, in addition to other residual structure, has been proposed to play a role in decreasing the free energy of the unfolded state of the protein. Together these data provide evidence that both increasing the free energy of the folded state and decreasing the free energy of the unfolded state of the protein contribute to instability of the WT drkN SH3 domain.