Secretion of RTX leukotoxin by Actinobacillus actinomycetemcomitans

被引:84
作者
Kachlany, SC
Fine, DH
Figurski, DH
机构
[1] Columbia Univ Coll Phys & Surg, Dept Microbiol, New York, NY 10032 USA
[2] Univ Med & Dent New Jersey, Dept Oral Biol & Pathol, Newark, NJ 07103 USA
关键词
D O I
10.1128/IAI.68.11.6094-6100.2000
中图分类号
R392 [医学免疫学]; Q939.91 [免疫学];
学科分类号
100102 ;
摘要
Actinobacillus actinomycetemcomitans, the etiologic agent for localized juvenile periodontitis and certain other human infections, such as endocarditis, expresses a leukotoxin that acts on polymorphonuclear leukocytes and macrophages. Leukotoxin is a member of the highly conserved repeat toxin (RTX) family of bacterial toxins expressed by a variety of pathogenic bacteria. While the RTX toxins of other bacterial species are secreted, the leukotoxin of A. actinomycetemcomitans is thought to remain associated with the bacterial cell. We have examined leukotoxin production and localization in rough (adherent) and smooth (nonadherent) strains of A. actinomycetemcomitans. We found that leukotoxin expressed by the rough, adherent, clinical isolate CU1000N is indeed cell associated, as expected. However, we were surprised to find that smooth, nonadherent strains of A. actinomycetemcomitans, including Y4, JP2 (a strain expressing a high level of toxin), and CU1060N tan isogenic smooth variant of CU1000N), secrete an abundance of leukotoxin into the culture supernatants during early stages of growth. After longer times of incubation, leukotoxin disappears from the supernatants, and its Loss is accompanied by the appearance of a number of low-molecular-weight polypeptides. The secreted leukotoxin is active, as evidenced by its ability to kill HL-60 cells in vitro. We found that the growth phase and initial pH of the growth medium significantly affect the abundance of secreted leukotoxin, and we have developed a rapid (<2 h) method to partially purify large amounts of leukotoxin. Remarkably, mutations in the tad genes, which are required for tight nonspecific adherence of A. actinomycetemcomitans to surfaces, cause leukotoxin to be released from the bacterial cell. These studies show that A. actinomycetemcomitans has the potential to secrete abundant leukotoxin. It is therefore appropriate to consider a possible role for leukotoxin secretion in the pathogenesis of A. actinomycetemcomitans.
引用
收藏
页码:6094 / 6100
页数:7
相关论文
共 64 条
[1]  
Ausubel FA, 1995, CURRENT PROTOCOLS MO
[2]   Reversible adsorption and nonreversible insertion of Escherichia coli alpha-hemolysin into lipid bilayers [J].
Bakas, L ;
Ostolaza, H ;
Vaz, WLC ;
Goni, FM .
BIOPHYSICAL JOURNAL, 1996, 71 (04) :1869-1876
[3]   ELECTRON IMMUNOCYTOCHEMICAL LOCALIZATION OF ACTINOBACILLUS-ACTINOMYCETEMCOMITANS LEUKOTOXIN [J].
BERTHOLD, P ;
FORTI, D ;
KIEBA, IR ;
ROSENBLOOM, J ;
TAICHMAN, NS ;
LALLY, ET .
ORAL MICROBIOLOGY AND IMMUNOLOGY, 1992, 7 (01) :24-27
[4]   ESCHERICHIA-COLI HEMOLYSIN MAY DAMAGE TARGET-CELL MEMBRANES BY GENERATING TRANSMEMBRANE PORES [J].
BHAKDI, S ;
MACKMAN, N ;
NICAUD, JM ;
HOLLAND, IB .
INFECTION AND IMMUNITY, 1986, 52 (01) :63-69
[5]   DAMAGE TO MAMMALIAN-CELLS BY PROTEINS THAT FORM TRANSMEMBRANE PORES [J].
BHAKDI, S ;
TRANUMJENSEN, J .
REVIEWS OF PHYSIOLOGY BIOCHEMISTRY AND PHARMACOLOGY, 1987, 107 :147-223
[6]   Protein secretion by Gram-negative bacterial ABC exporters - A review [J].
Binet, R ;
Letoffe, S ;
Ghigo, JM ;
Delepelaire, P ;
Wandersman, C .
GENE, 1997, 192 (01) :7-11
[7]   DOMAINS OF ESCHERICHIA-COLI HEMOLYSIN (HLYA) INVOLVED IN BINDING OF CALCIUM AND ERYTHROCYTE-MEMBRANES [J].
BOEHM, DF ;
WELCH, RA ;
SNYDER, IS .
INFECTION AND IMMUNITY, 1990, 58 (06) :1959-1964
[9]   Type III secretion by Salmonella typhimurium does not require contact with a eukaryotic host [J].
Daefler, S .
MOLECULAR MICROBIOLOGY, 1999, 31 (01) :45-51
[10]  
England S., 1990, METHOD ENZYMOL, P285, DOI 10.1016/0076-6879(90)82024-v