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Journal of Bacteriology, October 2000, p. 5586-5591, Vol. 182, No. 19
The Maxwell Finland Laboratory for Infectious
Diseases, Department of Medicine, Boston University School of
Medicine, Boston, Massachusetts 02118
Received 24 April 2000/Accepted 6 July 2000
Redundant TonB systems which function in iron transport from
TonB-dependent ligands have recently been identified in several gram-negative bacteria. We demonstrate here that in addition to the
previously described tonB locus, an alternative system
exists for the utilization of iron from hemoglobin, transferrin, or
lactoferrin in Neisseria meningitidis and
Neisseria gonorrhoeae. Following incubation on media
containing hemoglobin, N. meningitidis IR3436 (tonB exbB exbD deletion mutant) and N. gonorrhoeae PD3401 (tonB insertional mutant) give
rise to colonies which can grow with hemoglobin. Transfer of
Hb+ variants (PD3437 or PD3402) to media
containing hemoglobin, transferrin, and/or lactoferrin as sole iron
sources resulted in growth comparable to that observed for the
wild-type strains. Transformation of N. meningitidis IR3436
or N. gonorrhoeae PD3401 with chromosomal DNA from the
Hb+ variants yielded transformants capable of growth with
hemoglobin. When we inactivated the TonB-dependent outer membrane
hemoglobin receptors (HmbR or HpuB) in the Neisseria
Hb+ variants, these strains could not grow with hemoglobin;
however, growth was observed with transferrin and/or lactoferrin. These results demonstrate that accumulation of iron from hemoglobin, transferrin, and lactoferrin in the pathogenic neisseriae can occur via
a system that is independent of the previously described tonB locus.
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Pathogenic Neisseriae Can Use Hemoglobin,
Transferrin, and Lactoferrin Independently of the tonB
Locus
*
Corresponding author. Mailing address: The Maxwell
Finland Laboratory for Infectious Diseases, Department of Medicine,
Boston University School of Medicine, 650 Albany St., Boston, MA 02118. Phone: (617) 414-5305. Fax: (617) 414-5280. E-mail:
caroline.genco{at}bmc.org.
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