Biological Assembly 1  

 3D View: Structure | 1D-3D View | Validation Report

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 11.48 kDa 
• Atom Count: 811 
• Modelled Residue Count: 105 
• Deposited Residue Count: 105 
• Unique protein chains: 1

1T4Z

Solution structure of the N-terminal domain of Synechococcus elongatus SasA (25-structures ensemble)

• PDB DOI: 10.2210/pdb1T4Z/pdb
• BMRB: 5141

• Classification: TRANSFERASE
• Organism(s): Synechococcus elongatus PCC 7942 = FACHB-805
• Expression System: Escherichia coli BL21(DE3)
• Mutation(s): No 


• Deposited: 2004-04-30 Released: 2004-11-16 
• Deposition Author(s): Vakonakis, I., Klewer, D.A., LiWang, A.C.

---

Experimental Data Snapshot

• Method: SOLUTION NMR
• Conformers Calculated: 50 
• Conformers Submitted: 25 
• Selection Criteria: structures with the lowest energy 

Literature

Structure of the N-terminal domain of the circadian clock-associated histidine kinase SasA.

Vakonakis, I., Klewer, D.A., Williams, S.B., Golden, S.S., LiWang, A.C.

(2004) J Mol Biol 342: 9-17

• PubMed: 15313603 
• DOI: 10.1016/j.jmb.2004.07.010
• Primary Citation of Related Structures:  
  1T4Y, 1T4Z


• PubMed Abstract: 
  

Circadian oscillators are endogenous biological systems that generate the approximately 24 hour temporal pattern of biological processes and confer a reproductive fitness advantage to their hosts. The cyanobacterial clock is the simplest known and the only clock system for which structural information for core component proteins, in this case KaiA, KaiB and KaiC, is available. SasA, a clock-associated histidine kinase, is necessary for robustness of the circadian rhythm of gene expression and implicated in clock output. The N-terminal domain of SasA (N-SasA) interacts directly with KaiC and likely functions as the sensory domain controlling the SasA histidine kinase activity. N-SasA and KaiB share significant sequence similarity and, thus, it has been proposed that they would be structurally similar and may even compete for KaiC binding. Here, we report the NMR structure of N-SasA and show it to be different from that of KaiB. The structural comparisons provide no clear details to suggest competition of SasA and KaiB for KaiC binding. N-SasA adopts a canonical thioredoxin fold but lacks the catalytic cysteine residues. A patch of conserved, solvent-exposed residues is found near the canonical thioredoxin active site. We suggest that this surface is used by N-SasA for protein-protein interactions. Our analysis suggests that the structural differences between N-SasA and KaiB are the result of only a few critical amino acid substitutions.

---

Organizational Affiliation: 

Department of Biochemistry and Biophysics, Texas A&M University, College Station 77843, USA.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Adaptive-response sensory-kinase sasA	A	105	Synechococcus elongatus PCC 7942 = FACHB-805	Mutation(s): 0  Gene Names: sasA, sarS, Synpcc7942_2114 EC: 2.7 (PDB Primary Data), 2.7.13.3 (UniProt)
UniProt
Find proteins for Q06904 (Synechococcus elongatus (strain PCC 7942 / FACHB-805)) Explore Q06904  Go to UniProtKB:  Q06904

Experimental Data & Validation

Experimental Data

• Method: SOLUTION NMR
• Conformers Calculated: 50 
• Conformers Submitted: 25 
• Selection Criteria: structures with the lowest energy 
• OLDERADO: 1T4Z Olderado

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2004-04-30 
• Released Date: 2004-11-16 
Deposition Author(s): Vakonakis, I., Klewer, D.A., LiWang, A.C.

Revision History  

• Version 1.0: 2004-11-16
  Type: Initial release
  
• Version 1.1: 2008-04-30
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Source and taxonomy, Version format compliance