Polar targeting of Shigella virulence factor IcsA in Enterobacteriacae and Vibrio.
Asymmetric localization is key to the proper function of certain prokaryotic proteins important to virulence, chemotaxis, cell division, development, motility, and adhesion. Shigella IcsA is localized to the old pole of the bacterium, where it mediates assembly of an actin tail inside infected mammalian cells. IcsA (VirG) is essential to Shigella intracellular motility and virulence. We used translational fusions between portions of IcsA and the green fluorescent protein (GFP) to determine the regions of IcsA that are necessary and sufficient for its targeting to the bacterial old pole. An IcsA-GFP fusion that lacks a signal peptide localized to the old pole, indicating that signal peptide-mediated secretion is not required for polar localization. Two regions within IcsA were required for localization of an IcsA-GFP fusion to the old pole. Further characterization of these regions indicated that amino acids 1-104 and 507-620 were each independently sufficient for polar localization. Finally, when expressed in Escherichia coli, Salmonella typhimurium, Yersinia pseudotuberculosis, and Vibrio cholerae, each of the two targeting regions localized to the pole, indicating that the mechanism of polar targeting used by IcsA is present generally among Enterobacteriacae and Vibrio.
Charles
M
M
Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Pérez
M
M
Kobil
J H
JH
Goldberg
M B
MB
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016764:Cell Polarity; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004755:Enterobacteriaceae / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000032:analysis / Q000378:metabolism; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D012763:Shigella flexneri / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity / Q000648:ultrastructure; D013045:Species Specificity; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014734:Vibrio cholerae / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D014774:Virulence / Q000235:genetics; D015011:Yersinia pseudotuberculosis / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C058483:virG protein, Shigella flexneri; D049452:Green Fluorescent Proteins