Subunit composition and domain structure of the Spo0A sporulation transcription factor of Bacillus subtilis

Document Type

Article

Abstract

The Spo0A transcription factor is responsible for the initiation of sporulation and is active in transcription only after phosphorylation by a specific signal transduction pathway, the phosphorelay. The effect of phosphorylation on the physical properties of Spo0A was determined. Spo0A and Spo0A approximately P both behaved as monomers during Sephacryl chromatography and gel electrophoresis, suggesting that phosphorylation did not modify the oligomerization state of the protein. Trypsin digested Spo0A at a single cleavage site between residues 142 and 143 within a hinge connecting two tightly folded domains. The amino domain retains ability to be phosphorylated by the phosphorelay. The carboxyl domain is active as a DNA-binding protein and retains the sequence specificity of the intact molecule for 0A boxes on the abrB promoter as revealed by footprinting studies. The carboxyl domain stimulated in vitro transcription from the spoIIG promoter 5-fold greater than an equal amount of Spo0A and about half as well as equivalent amounts of Spo0A approximately P. Thus, the unphosphorylated amino domain inhibits the transcription stimulation activity of the carboxyl domain. We suggest that phosphorylation activates transcription regulation functions of Spo0A by modifying the spatial relationships of the amino and carboxyl domains.

Medical Subject Headings

Bacillus subtilis (metabolism); Bacterial Proteins (chemistry, isolation & purification, metabolism); Base Sequence; Binding Sites; Chromatography, Affinity; Chromatography, Gel; Cloning, Molecular; Electrophoresis, Polyacrylamide Gel; Escherichia coli; Genes, Bacterial; Kinetics; Macromolecular Substances; Molecular Sequence Data; Molecular Weight; Oligodeoxyribonucleotides (metabolism); Peptide Fragments (chemistry, isolation & purification); Peptide Mapping; Phosphorylation; Promoter Regions, Genetic; Protein Folding; Recombinant Proteins (chemistry, isolation & purification, metabolism); Transcription Factors (chemistry, isolation & purification, metabolism)

Publication Date

6-17-1994

Publication Title

The Journal of biological chemistry

ISSN

0021-9258

Volume

269

Issue

24

First Page

16977

Last Page

82

PubMed ID

8207022

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