J Biol Chem, Vol. 273, Issue 28, 17326-17332, July 10, 1998
Identification of Protein-Protein Contacts between
/
-Type
Small, Acid-soluble Spore Proteins of Bacillus Species
Bound to DNA
Christopher S.
Hayes and
Peter
Setlow
From the Department of Biochemistry, University of Connecticut
Health Center, Farmington, Connecticut 06030
Small, acid-soluble spore proteins (SASP)
of the
/
-type from several Bacillus species were
cross-linked into homodimers, heterodimers and homooligomers with
1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) in the presence of
linear plasmid DNA. Significant protein cross-linking was not detected
in the absence of DNA. In all four
/
-type SASP examined, the
amino donor in the EDC induced amide cross-links was the
-amino
group of the protein. However, the carboxylate containing amino acid
residues involved in cross-linking varied. In SASP-A and SASP-C of
Bacillus megaterium two conserved glutamate residues, which
form part of the germination protease recognition sequence, were
involved in cross-link formation. In SspC from Bacillus
subtilis and Bce1 from Bacillus cereus the acidic
residues involved in cross-link formation were not in the protease
recognition sequence, but at a site closer to the N terminus of the
proteins. These data indicate that, although there are likely to be
subtle structural differences between different
/
-type SASP, the
N-terminal regions of these proteins are involved in protein-protein
interactions while in the DNA bound state.
Copyright © 1998 by The American Society for Biochemistry and Molecular Biology, Inc.