Function 
Stringent starvation protein A (SspA) is an RNA polymerase-associated protein involved in nucleotide metabolism, acid tolerance[1] and virulence of bacteria[2].
In Francisella virulence, a set of regulators are essensial for its activation.  These regulators include the heterodimer of SspA, macrophage growth locus A (MglA) and pathogenicity island gene regulator (PigR).  The guanosine-tetraphosphate (ppGpp) is also involved in coordinating the virulence. Stringent starvation protein B (SspB) binds to residues in the tag of tmRNA proteins marking them for degradation [3]. 
  Relevance 
Tularemia caused by the pathogen Francisella tularensis may be treated by inhibitors of SspA-MglA regulators[4].
  Structural highlights 
The 3D structure of the complex of SspA and MglA shows a heterodimer with favourable interactions between the two molecules[5]. The .
  3D structures of stringent starvation protein 
Stringent starvation protein 3D structures