Previous Article | Next Article ![]()
Journal of Bacteriology, January 1999, p. 212-217, Vol. 181, No. 1
Departamento de Biología, Facultad de
Ciencias, Universidad de Chile, Santiago, Chile
Received 18 May 1998/Accepted 29 October 1998
The gene coding for the immunity protein (mceB) and the
structural gene of microcin E492 (mceA), a
low-molecular-weight channel-forming bacteriocin produced by a strain
of Klebsiella pneumoniae, have been characterized. The
microcin gene codes for a precursor protein of either 99 or 103 amino
acids. Protein sequencing of the N-terminal region of microcin E492
unequivocally identified this gene as the microcin structural gene and
indicated that this microcin is synthesized as a precursor protein that
is cleaved at either amino acid 15 or 19, at a site resembling the
double-glycine motif. The gene encoding the 95-amino-acid immunity
protein (mceB) was identified by cloning the DNA segment
that encodes only this polypeptide into an expression vector and
demonstrating the acquisition of immunity to microcin E492. As
expected, the immunity protein was found to be associated with the
inner membrane. Analysis of the DNA sequence indicates that these genes
belong to the same family as microcin 24, and they do not share
structural motifs with any other known channel-forming bacteriocin. The
organization of the microcin- and immunity protein-encoding genes
suggests that they are coordinately expressed.
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Identification and Properties of the Genes Encoding
Microcin E492 and Its Immunity Protein
and
*
Corresponding author. Mailing address: Departamento de
Biología, Facultad de Ciencias, Universidad de Chile, Casilla
653, Santiago, Chile. Phone: 56-2-678-7338. Fax: 56-2-271-3891. E-mail: rolagos{at}abello.dic.uchile.cl.
Permanent address: Facultad de Ciencias, Campus San Andrés,
Universidad Católica de la Santísima Concepción,
Concepción, Chile.
| Appl. Environ. Microbiol. | Infect. Immun. | Eukaryot. Cell |
|---|---|---|
| Mol. Cell. Biol. | J. Virol. | Microbiol. Mol. Biol. Rev. |
| ALL ASM JOURNALS |