Structure of CutA from Synechococcus elongatus PCC7942

Experimental Data Snapshot

  • Resolution: 1.75 Å
  • R-Value Free: 0.232 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.199 

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This is version 1.3 of the entry. See complete history


Functional and structural characterization of PII-like protein CutA does not support involvement in heavy metal tolerance and hints at a small-molecule carrying/signaling role.

Selim, K.A.Tremino, L.Marco-Marin, C.Alva, V.Espinosa, J.Contreras, A.Hartmann, M.D.Forchhammer, K.Rubio, V.

(2020) FEBS J 

  • DOI: https://doi.org/10.1111/febs.15464
  • Primary Citation of Related Structures:  
    6GDU, 6GDV, 6GDW, 6GDX, 6T76, 6T7E

  • PubMed Abstract: 

    The PII-like protein CutA is annotated as being involved in Cu 2+ tolerance, based on analysis of Escherichia coli mutants. However, the precise cellular function of CutA remains unclear. Our bioinformatic analysis reveals that CutA proteins are universally distributed across all domains of life. Based on sequence-based clustering, we chose representative cyanobacterial CutA proteins for physiological, biochemical, and structural characterization and examined their involvement in heavy metal tolerance, by generating CutA mutants in filamentous Nostoc sp. and in unicellular Synechococcus elongatus. However, we were unable to find any involvement of cyanobacterial CutA in metal tolerance under various conditions. This prompted us to re-examine experimentally the role of CutA in protecting E. coli from Cu 2+ . Since we found no effect on copper tolerance, we conclude that CutA plays a different role that is not involved in metal protection. We resolved high-resolution CutA structures from Nostoc and S. elongatus. Similarly to their counterpart from E. coli and to canonical PII proteins, cyanobacterial CutA proteins are trimeric in solution and in crystal structure; however, no binding affinity for small signaling molecules or for Cu 2+ could be detected. The clefts between the CutA subunits, corresponding to the binding pockets of PII proteins, are formed by conserved aromatic and charged residues, suggesting a conserved binding/signaling function for CutA. In fact, we find binding of organic Bis-Tris/MES molecules in CutA crystal structures, revealing a strong tendency of these pockets to accommodate cargo. This highlights the need to search for the potential physiological ligands and for their signaling functions upon binding to CutA. DATABASES: Structural data are available in Protein Data Bank (PDB) under the accession numbers 6GDU, 6GDV, 6GDW, 6GDX, 6T76, and 6T7E.

  • Organizational Affiliation

    Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Spain.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Periplasmic divalent cation tolerance protein
A, B, C
133Synechococcus elongatus PCC 7942 = FACHB-805Mutation(s): 0 
Gene Names: Synpcc7942_2261
Find proteins for Q31KX8 (Synechococcus elongatus (strain ATCC 33912 / PCC 7942 / FACHB-805))
Explore Q31KX8 
Go to UniProtKB:  Q31KX8
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ31KX8
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.75 Å
  • R-Value Free: 0.232 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.199 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 35.149α = 90
b = 96.371β = 94.19
c = 48.977γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
Aimlessdata scaling

Structure Validation

View Full Validation Report

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Spanish Ministry of Economy and CompetitivenessSpainBFU2014-58229-P
Other governmentSpainPrometeo II/2014/029

Revision History  (Full details and data files)

  • Version 1.0: 2019-05-08
    Type: Initial release
  • Version 1.1: 2020-07-22
    Changes: Database references
  • Version 1.2: 2021-06-02
    Changes: Data collection
  • Version 1.3: 2024-01-17
    Changes: Data collection, Database references, Refinement description