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Mutational analysis of the activator of late transcription, Alt, in the lactococcal bacteriophage TP901-1

Mutational analysis of the activator of late transcription, Alt, in the lactococcal bacteriophage... An activator protein, Alt, synthesized during the early state of lytic infection is required for transcription of the late operon in the lactococcal phage TP901-1. In order to identify amino acid residues in the Alt protein required for activation of the TP901-1 late promoter, P late , hydroxylamine mutagenesis was performed, resulting in almost saturating mutagenesis of alt . Twenty-three different non-functional alt alleles containing one, and in one case two amino acid exchanges were isolated and analyzed. Eight of the twenty-three mutant proteins were still able to activate the P late promoter to some extent. Our results show that alt encodes a protein of 16.7 kDa and that the last fourteen amino acids in the C-terminal part of the protein are required for activation of the P late promoter. By combining sequence analysis with experimental data we suggest that the C-terminal half of the Alt protein contains a helix-turn-helix-like motif involved in DNA binding. We also propose that the C-terminal half of the Alt protein may be involved in interactions with the bacterial RNA polymerase, whereas the N-terminal half of the protein is proposed to be important for the overall protein structure. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Virology Springer Journals

Mutational analysis of the activator of late transcription, Alt, in the lactococcal bacteriophage TP901-1

Archives of Virology , Volume 152 (2) – Feb 1, 2007

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References (33)

Publisher
Springer Journals
Copyright
Copyright © 2007 by Springer-Verlag
Subject
Biomedicine; Medical Microbiology; Virology; Infectious Diseases
ISSN
0304-8608
eISSN
1432-8798
DOI
10.1007/s00705-006-0851-7
pmid
17066250
Publisher site
See Article on Publisher Site

Abstract

An activator protein, Alt, synthesized during the early state of lytic infection is required for transcription of the late operon in the lactococcal phage TP901-1. In order to identify amino acid residues in the Alt protein required for activation of the TP901-1 late promoter, P late , hydroxylamine mutagenesis was performed, resulting in almost saturating mutagenesis of alt . Twenty-three different non-functional alt alleles containing one, and in one case two amino acid exchanges were isolated and analyzed. Eight of the twenty-three mutant proteins were still able to activate the P late promoter to some extent. Our results show that alt encodes a protein of 16.7 kDa and that the last fourteen amino acids in the C-terminal part of the protein are required for activation of the P late promoter. By combining sequence analysis with experimental data we suggest that the C-terminal half of the Alt protein contains a helix-turn-helix-like motif involved in DNA binding. We also propose that the C-terminal half of the Alt protein may be involved in interactions with the bacterial RNA polymerase, whereas the N-terminal half of the protein is proposed to be important for the overall protein structure.

Journal

Archives of VirologySpringer Journals

Published: Feb 1, 2007

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