SSF52091

SpoIIaa-like

SUPERFAMILY entry
Member databaseSUPERFAMILY
SUPERFAMILY typehomologous superfamily

Description
Imported from IPR036513

The STAS (Sulphate Transporter and AntiSigma factor antagonist) domain is found in the bacterial anti-sigma factor antagonists (ASA) and the C-terminal region of SLC26 (SulP) anion transporters.

The activity of bacterial sigma transcription factors is controlled by a regulatory cascade involving an antisigma-factor, the antisigma-factor antagonist (ASA) and a phosphatase. The antisigma-factor binds to sigma and holds it in an inactive complex. The ASA can also interact with the anti-sigma-factor, allowing the release of the active sigma factor. As the antisigma-factor is a protein kinase, it can phosphorylate the antisigma antagonist on a conserved serine residue of the STAS domain. This phosphorylation inactivates the ASA that can be reactivated through dephosphorylation by a phosphatase
[3, 2]
. The STAS domain of the ASA SpoIIAA binds GTP and ATP and possesses a weak NTPase activity. Strong sequence conservation suggests that the STAS domain could possess general NTP-binding activity, and it has been proposed that the NTPs are likely to elicit specific conformational changes in the STAS domain through binding and/or hydrolysis
[3]
. Resolution of the solution structure of the ASA SpoIIAA from Bacillus subtilis has shown that the STAS domain consists of a four-stranded β-sheet and four α-helices. The STAS domain forms a characteristic α-helical handle-like structure
[3, 4]
.

The STAS domain of E. coli YchM protein, a SLC26 (SulP) family member, has been shown to interact with acyl carrier protein (ACP), which is an activated thiol ester carrier of acyl intermediates during fatty acid biosynthesis (FAB) and other acylation reactions
[1]
.

Malfunctions in members of the SLC26A family of anion transporters are involved in three human diseases: diastrophic dysplasia/achondrogenesis type 1B (DTDST), Pendred's syndrome (PDS) and congenital chloride diarrhea (CLD). These proteins contain 12 transmembrane helices followed by a cytoplasmic STAS domain at the C terminus. The importance of the STAS domain in these transporters is illustrated by the fact that a number of mutations in PDS and DTDST map to it
[3, 5]
.

References
Imported from IPR036513

1.Structure of a SLC26 anion transporter STAS domain in complex with acyl carrier protein: implications for E. coli YchM in fatty acid metabolism. Babu M, Greenblatt JF, Emili A, Strynadka NC, Reithmeier RA, Moraes TF. Structure 18, 1450-62, (2010). View articlePMID: 21070944

2.Characterization of a morphological checkpoint coupling cell-specific transcription to septation in Bacillus subtilis. Feucht A, Daniel RA, Errington J. Mol. Microbiol. 33, 1015-26, (1999). View articlePMID: 10476035

3.The STAS domain - a link between anion transporters and antisigma-factor antagonists. Aravind L, Koonin EV. Curr. Biol. 10, R53-5, (2000). View articlePMID: 10662676

4.Solution structure of SpoIIAA, a phosphorylatable component of the system that regulates transcription factor sigmaF of Bacillus subtilis. Kovacs H, Comfort D, Lord M, Campbell ID, Yudkin MD. Proc. Natl. Acad. Sci. U.S.A. 95, 5067-71, (1998). View articlePMID: 9560229

5.STAS domain structure and function. Sharma AK, Rigby AC, Alper SL. Cell. Physiol. Biochem. 28, 407-22, (2011). PMID: 22116355

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