3URC

T181G mutant of alpha-Lytic Protease

Summary for 3URC

• Entry DOI: 10.2210/pdb3urc/pdb
• Related: 1SSX 2ALP 2OUA 2PFE 3URD 3URE 4SGB
• Descriptor: Alpha-lytic protease, SULFATE ION, GLYCEROL, ... (4 entities in total)
• Functional Keywords: serine protease, hydrolase
• Biological source: Lysobacter enzymogenes
• Total number of polymer chains: 1
• Total formula weight: 20115.30

Authors

Kelch, B.A.,Agard, D.A. (deposition date: 2011-11-22, release date: 2012-05-23, Last modification date: 2019-07-17)

Primary citation

Kelch, B.A.,Salimi, N.L.,Agard, D.A.
Functional modulation of a protein folding landscape via side-chain distortion.
Proc.Natl.Acad.Sci.USA, 109:9414-9419, 2012

PubMed Abstract: Ultrahigh-resolution (< 1.0 Å) structures have revealed unprecedented and unexpected details of molecular geometry, such as the deformation of aromatic rings from planarity. However, the functional utility of such energetically costly strain is unknown. The 0.83 Å structure of α-lytic protease (αLP) indicated that residues surrounding a conserved Phe side-chain dictate a rotamer which results in a ~6° distortion along the side-chain, estimated to cost 4 kcal/mol. By contrast, in the closely related protease Streptomyces griseus Protease B (SGPB), the equivalent Phe adopts a different rotamer and is undistorted. Here, we report that the αLP Phe side-chain distortion is both functional and conserved in proteases with large pro regions. Sequence analysis of the αLP serine protease family reveals a bifurcation separating those sequences expected to induce distortion and those that would not, which correlates with the extent of kinetic stability. Structural and folding kinetics analyses of family members suggest that distortion of this side-chain plays a role in increasing kinetic stability within the αLP family members that use a large Pro region. Additionally, structural and kinetic folding studies of mutants demonstrate that strain alters the folding free energy landscape by destabilizing the transition state (TS) relative to the native state (N). Although side-chain distortion comes at a cost of foldability, it suppresses the rate of unfolding, thereby enhancing kinetic stability and increasing protein longevity under harsh extracellular conditions. This ability of a structural distortion to enhance function is unlikely to be unique to αLP family members and may be relevant in other proteins exhibiting side-chain distortions.

PubMed: 22635267
DOI: 10.1073/pnas.1119274109

Experimental method

X-RAY DIFFRACTION (1.1 Å)