The ea22 gene resides in a relatively uncharacterized region of the lambda bacteriophage genome between the exo and xis genes and is among the earliest genes transcribed upon infection. In lambda and Shiga toxin-producing phages found in enterohemorrhagic E. coli (EHEC) associated with food poisoning, Ea22 favors a lysogenic over lytic developmental state. The Ea22 protein may be considered in terms of three domains: a short amino-terminal domain, a coiled-coiled domain, and a carboxy-terminal domain (CTD). While the full-length protein is tetrameric, the CTD is dimeric when expressed individually. Here, we report the NMR solution structure of the Ea22 CTD that is described by a mixed alpha-beta fold with a dimer interface reinforced by salt bridges. A conserved mobile loop may serve as a ligand for an unknown host protein that works with Ea22 to promote bacterial survival and the formation of new lysogens. From sequence and structural comparisons, the CTD distinguishes lambda Ea22 from homologs encoded by Shiga toxin-producing bacteriophages.
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http://dx.doi.org/10.1038/s41598-024-52996-3 | DOI Listing |
Sci Rep
February 2024
Department of Biology, York University, Toronto, ON, M3J1P3, Canada.
The ea22 gene resides in a relatively uncharacterized region of the lambda bacteriophage genome between the exo and xis genes and is among the earliest genes transcribed upon infection. In lambda and Shiga toxin-producing phages found in enterohemorrhagic E. coli (EHEC) associated with food poisoning, Ea22 favors a lysogenic over lytic developmental state.
View Article and Find Full Text PDFCells
December 2020
Department of Agricultural Biotechnology, Centre for Food and Bioconvergence, and Research Institute for Agriculture and Life Sciences, CALS, Seoul National University, Seoul 08826, Korea.
Intermediate filaments (IFs) commonly have structural elements of a central α-helical coiled-coil domain consisting of coil 1a, coil 1b, coil 2, and their flanking linkers. Recently, the crystal structure of a long lamin A/C fragment was determined and showed detailed features of a tetrameric unit. The structure further suggested a new binding mode between tetramers, designated eA22, where a parallel overlap of coil 1a and coil 2 is the critical interaction.
View Article and Find Full Text PDFACS Omega
June 2020
Department of Biology, York University, 4700 Keele Street, Toronto, ON, Canada M3J 1P3.
Enterohemorrhagic (EHEC) outbreaks are commonly associated with contaminated food sources. Unlike normal intestinal bacteria, EHEC are lysogens of lambdoid bacteriophages that also carry a gene for Shiga toxin. Oxidative attack by the immune system or other stressors on the bacterial host can activate the lytic pathway of the latent phage genome to produce phage progeny and the release of Shiga toxin into the surrounding tissues.
View Article and Find Full Text PDFRestriction fragments of bacteriophage lambda DNA corresponding to the major leftward transcription unit were purified, denatured to form single-stranded DNA, self-annealed, and examined by electron microscopy. Three intrastrand stem and loop secondary structures were observed reproducibly and the locations of the paired regions were determined. A method for computer-aided sequence analysis of these regions is presented and used to identify sets of base-pairings likely to account for the observed structures.
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