The crystal structure of a cold-adapted acylaminoacyl peptidase reveals a novel quaternary architecture based on the arm-exchange mechanism

Experimental Data Snapshot

  • Resolution: 2.50 Å
  • R-Value Free: 0.248 
  • R-Value Work: 0.212 
  • R-Value Observed: 0.214 

wwPDB Validation   3D Report Full Report

This is version 1.1 of the entry. See complete history


A bacterial acyl aminoacyl peptidase couples flexibility and stability as a result of cold adaptation.

Brocca, S.Ferrari, C.Barbiroli, A.Pesce, A.Lotti, M.Nardini, M.

(2016) FEBS J 283: 4310-4324

  • DOI: https://doi.org/10.1111/febs.13925
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Life in cold environments requires an overall increase in the flexibility of macromolecular and supramolecular structures to allow biological processes to take place at low temperature. Conformational flexibility supports high catalytic rates of enzymes in the cold but in several cases is also a cause of instability. The three-dimensional structure of the psychrophilic acyl aminoacyl peptidase from Sporosarcina psychrophila (SpAAP) reported in this paper highlights adaptive molecular changes resulting in a fine-tuned trade-off between flexibility and stability. In its functional form SpAAP is a dimer, and an increase in flexibility is achieved through loosening of intersubunit hydrophobic interactions. The release of subunits from the quaternary structure is hindered by an 'arm exchange' mechanism, in which a tiny structural element at the N terminus of one subunit inserts into the other subunit. Mutants lacking the 'arm' are monomeric, inactive and highly prone to aggregation. Another feature of SpAAP cold adaptation is the enlargement of the tunnel connecting the exterior of the protein with the active site. Such a wide channel might compensate for the reduced molecular motions occurring in the cold and allow easy and direct access of substrates to the catalytic site, rendering transient movements between domains unnecessary. Thus, cold-adapted SpAAP has developed a molecular strategy unique within this group of proteins: it is able to enhance the flexibility of each functional unit while still preserving sufficient stability.

  • Organizational Affiliation

    Department of Biosciences, University of Milano, Italy.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Amino acyl peptidase
A, B, C, D
604Sporosarcina psychrophilaMutation(s): 0 
Gene Names: aphAZE41_09720
Find proteins for E1VFE0 (Sporosarcina psychrophila)
Explore E1VFE0 
Go to UniProtKB:  E1VFE0
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupE1VFE0
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.50 Å
  • R-Value Free: 0.248 
  • R-Value Work: 0.212 
  • R-Value Observed: 0.214 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 148.08α = 90
b = 151.1β = 90
c = 191.23γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
SCALAdata scaling

Structure Validation

View Full Validation Report

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Fondo di Ateneo of the University of Milano-Milano BicoccaItaly--

Revision History  (Full details and data files)

  • Version 1.0: 2016-11-16
    Type: Initial release
  • Version 1.1: 2016-12-14
    Changes: Database references