Global Proteome Analysis of Leptospira interrogans

Abstract

Comparative global proteome analyses were performed on Leptospira interrogans serovar Copenhageni grown under conventional in vitro conditions and those mimicking in vivo conditions (iron limitation and serum presence). Proteomic analyses were conducted using iTRAQ and LC-ESI-tandem mass spectrometry complemented with two-dimensional gel electrophoresis and MALDI-TOF mass spectrometry. A total of 563 proteins were identified in this study. Altered expression of 65 proteins, including upregulation of the L. interrogans virulence factor Loa22 and 5 novel proteins with homology to virulence factors found in other pathogens, was observed between the comparative conditions. Immunoblot analyses confirmed upregulation of 5 of the known or putative virulence factors in L. interrogans exposed to the in vivo-like environmental conditions. Further, ELISA analyses using serum from patients with leptospirosis and immunofluorescence studies performed on liver sections derived from L. interrogans-infected hamsters verified expression of all but one of the identified proteins during infection. These studies, which represent the first documented comparative global proteome analysis of Leptospira, demonstrated proteome alterations under conditions that mimic in vivo infection and allowed for the identification of novel putative L. interrogans virulence factors.

Comparative proteogenomic analysis of the Leptospira interrogans virulence-attenuated strain IPAV against the pathogenic strain 56601

“…Although three copies of this kind of hybrid genes exist in the genome of strain 56601, only one (LA_1422, 1 780 aa) is highly expressed (520 peptides identified), whereas the other two gene products (LA_1164 and LA_3113) are almost undetectable in our MS data. In fact, similar MS results can also be found in the work for Copenhageni [20,30]. Compared with the genes from Figure 7A).…”

“…Quantitative proteomic studies for the two strains indicated that approximately half of the predicted proteins were validated (55.8% for strain IPAV and 59.8% for strain 56601), slightly more than that in recent studies for serovar Pomona [63] and Copenhageni [30]. Moreover, by searching the MS spectra against the six-frame translations of the genome sequence, 13 novel genes were detected.…”

Multiple Posttranslational Modifications of Leptospira biflexa Proteins as Revealed by Proteomic Analysis

“…contain multiple flaB loci, and the same allele is not consistently used between studies. Other reports have shown that flaB transcript and protein levels vary with growth conditions, indicating that flaB may not be the best choice as a normalizing control (14,16,41). Because we have identified endogenous proteins that appear to be as abundant as the FlaB1 protein (Fig.…”

“…No large-scale microarray data or extensive proteomic analyses have been reported for the saprophyte, although Thongboonkerd and colleagues compared total protein lysate of L. biflexa to multiple pathogenic strains to identify potential virulence factors (10). In contrast, extensive microarray and proteomic studies have been performed on various host-associated species (11)(12)(13)(14)(15)(16)(17)(18)(19)(20). These limitations in our basic knowledge of L. biflexa reduce its utility as a model organism, since there are no known protein markers for the outer membrane and no abundantly synthesized proteins have been reported.…”

Pathogenic Leptospira interrogans Exoproteins Are Primarily Involved in Heterotrophic Processes

“…Leptospires are unable to cross the skin barrier; they can, however, access the underlying tissues via cuts/wounds in the skin. After gaining access to underlying tissue, leptospires rapidly disseminate to the interstitial space in the kidneys and liver (6,7). While generally extracellular, studies have demonstrated transient intracellular localization in macrophages (8)(9)(10).…”