SMART: SPOB_ab domain annotation

SPOB_ab Sporulation initiation phospho-transferase B, C-terminal

SMART accession number:	SM01317
Description:	Sporulation initiation phospho-transferase B or SpoOB is part of a phospho-relay that initiates sporulation in Bacillus subtilis. Spo0B is a two-domain protein consisting of an N-terminal alpha-helical hairpin domain and a C-terminal alpha/beta domain, represented by this family. Two subunits of Spo0B dimerise by a parallel association of helical hairpins to form a novel four-helix bundle from which the active histidine - involved in the auto-phosphorylation - protrudes. In the phospho-relay, the signal-receptor histidine kinases are dephosphorylated by a common response regulator, Spo0F. Spo0B then takes phosphorylated Spo0F as substrate hereby mediating the transfer of a phosphoryl group to Spo0A, the ultimate transcription factor.
Interpro abstract (IPR016122):	Response regulatory proteins such as sensor kinases control a variety of environmentally induced responses in bacteria. SpoOB is a response regulator that responds to nutritional stress by inducing sporulation. SpoOB is a phosphotransferase that acts upon SpoOA using SpoOF as the phosphor-donor. Phosphorylated SpoOA ca activate sporulation-specific gene transcription [ (PUBMED:1664534) ]. SpoOB has an alpha-beta core structure that resembles the histidine kinase fold, but lacks the kinase ATP-binding site [ (PUBMED:9809070) ]. This domain is found at the C teminus of SpoOB, as well as in other sensor kinases.
Family alignment:	View or

There are 146 SPOB_ab domains in 146 proteins in SMART's nrdb database.

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Evolution (species in which this domain is found)
Taxonomic distribution of proteins containing SPOB_ab domain.
This tree includes only several representative species. The complete taxonomic breakdown of all proteins with SPOB_ab domain is also avaliable.

Click on the protein counts, or double click on taxonomic names to display all proteins containing SPOB_ab domain in the selected taxonomic class.
Cellular role (predicted cellular role)
Cellular role: transcription
Literature (relevant references for this domain)
Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.
- Varughese KI, Madhusudan, Zhou XZ, Whiteley JM, Hoch JA
- Formation of a novel four-helix bundle and molecular recognition sites bydimerization of a response regulator phosphotransferase.
- Mol Cell. 1998; 2: 485-93
- Display abstract
- A basis for understanding specificity of molecular recognition betweenphosphorelay proteins has been deduced from the 2.6 A structure of the Spo0Bphosphotransferase of the phosphorelay regulating sporulation initiation. Spo0Bconsists of two domains: an N-terminal alpha-helical hairpin domain and aC-terminal alpha/beta domain. Two subunits of Spo0B dimerize by a parallelassociation of helical hairpins to form a novel four-helix bundle from which the active histidine protrudes. Docking studies show that both the monomers interact with a Spo0F molecule at the region surrounding the active site aspartate toposition it for phosphotransfer. It is apparent that different surfaces ofresponse regulators may be involved in recognition of the protein partners towhich they are paired.
Structure (3D structures containing this domain)

Links (links to other resources describing this domain)
PFAM SPOB_ab
INTERPRO IPR016122

PDB code	Main view	Title
1f51		A TRANSIENT INTERACTION BETWEEN TWO PHOSPHORELAY PROTEINS TRAPPED IN A CRYSTAL LATTICE REVEALS THE MECHANISM OF MOLECULAR RECOGNITION AND PHOSPHOTRANSFER IN SINGAL TRANSDUCTION
1ixm		CRYSTAL STRUCTURE OF SPOOB FROM BACILLUS SUBTILIS
2ftk		berylloflouride Spo0F complex with Spo0B

PFAM	SPOB_ab
INTERPRO	IPR016122

SPOB_ab

Taxonomic distribution of proteins containing SPOB_ab domain.

3D Structures of SPOB_ab domains in PDB