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Infection and Immunity, September 2009, p. 4092-4101, Vol. 77, No. 9
0019-9567/09/$08.00+0     doi:10.1128/IAI.00353-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Plasminogen Acquisition and Activation at the Surface of Leptospira Species Lead to Fibronectin Degradation {triangledown}

Monica L. Vieira,1,2 Silvio A. Vasconcellos,3 Amane P. Gonçales,3 Zenaide M. de Morais,3 and Ana L. T. O. Nascimento1,2*

Centro de Biotecnologia, Instituto Butantan, Avenida Vital Brazil, 1500, 05503-900 Sao Paulo, SP, Brazil,1 Interunidades em Biotecnologia, Instituto de Ciências Biomédicas, USP, Sao Paulo, Brazil,2 Laboratorio de Zoonoses Bacterianas do VPS, Faculdade de Medicina Veterinária e Zootecnia da Universidade de Sao Paulo, Sao Paulo, Brazil3

Received 26 March 2009/ Returned for modification 29 April 2009/ Accepted 26 June 2009

Pathogenic Leptospira species are the etiological agents of leptospirosis, a widespread disease of human and veterinary concern. In this study, we report that Leptospira species are capable of binding plasminogen (PLG) in vitro. The binding to the leptospiral surface was demonstrated by indirect immunofluorescence confocal microscopy with living bacteria. The PLG binding to the bacteria seems to occur via lysine residues because the ligation is inhibited by addition of the lysine analog 6-aminocaproic acid. Exogenously provided urokinase-type PLG activator (uPA) converts surface-bound PLG into enzymatically active plasmin, as evaluated by the reaction with the chromogenic plasmin substrate D-Val-Leu-Lys 4-nitroanilide dihydrochloridein. The PLG activation system on the surface of Leptospira is PLG dose dependent and does not cause injury to the organism, as cellular growth in culture was not impaired. The generation of active plasmin within Leptospira was observed with several nonvirulent high-passage strains and with the nonpathogenic saprophytic organism Leptospira biflexa. Statistically significant higher activation of plasmin was detected with a low-passage infectious strain of Leptospira. Plasmin-coated virulent Leptospira interrogans bacteria were capable of degrading purified extracellular matrix fibronectin. The breakdown of fibronectin was not observed with untreated bacteria. Our data provide for the first time in vitro evidence for the generation of active plasmin on the surface of Leptospira, a step that may contribute to leptospiral invasiveness.

* Corresponding author. Mailing address: Centro de Biotecnologia, Instituto Butantan, Avenida Vital Brazil, 1500, 05503-900 Sao Paulo, SP, Brazil. Phone: (5511) 37220019. Fax: (5511) 37261505. E-mail: tabet{at}butantan.gov.br

{triangledown} Published ahead of print on 6 July 2009.

Editor: A. Camilli

Infection and Immunity, September 2009, p. 4092-4101, Vol. 77, No. 9
0019-9567/09/$08.00+0     doi:10.1128/IAI.00353-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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