Open AccessAggregatibacter actinomycetemcomitans leukotoxin requires β‐sheets 1 and 2 of the human CD11a β‐propeller for cytotoxicity
Author(s) -
Kieba Irene R.,
Fong Karen P.,
Tang HsinYao,
Hoffman Karl E.,
Speicher David W.,
Klickstein Lloyd B.,
Lally Edward T.
Publication year - 2007
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/j.1462-5822.2007.00989.x
Subject(s) - biology , cytolysin , cytolysis , aggregatibacter actinomycetemcomitans , transfection , cell culture , cytotoxicity , microbiology and biotechnology , mutant , toxin , gene , virulence , in vitro , biochemistry , bacteria , genetics , porphyromonas gingivalis
Summary Aggregatibacter actinomycetemcomitans leukotoxin (Ltx) is a repeats‐in‐toxin (RTX) cytolysin that kills human leukocyte function‐associated antigen‐1 (LFA‐1; α L /β 2 )‐bearing cells. In order to determine whether the α L portion of the heterodimer is involved in Ltx recognition, we transfected human, mouse and bovine α L cDNAs into J‐β 2 .7, an α L ‐deficient cell line, and looked for restoration of Ltx susceptibility. Cells expressing either bovine or human α L in conjunction with human β 2 were efficiently killed by Ltx, an indication that bovine α L could substitute for its human counterpart in critical regions used by Ltx for attachment to LFA‐1. On the other hand, cells expressing murine α L and human β 2 were not susceptible to the lethal effects of Ltx indicating that the toxin recognition sites are not present in the corresponding mouse sequence. To further identify the region(s) of α L recognized by Ltx, we constructed and evaluated a panel of chimeric human/murine α L genes in J‐β 2 .7 cells. Analysis of the α L mutant panel showed that the presence of human N‐terminal 128 amino acids on a mouse CD11a background, a region that includes β‐sheets 1 and 2 of the β‐propeller of the human α L chain, was sufficient for Ltx cytolysis.