The mammalian cell entry (Mce) protein of pathogenic <i>Leptospira</i> species is responsible for RGD motif‐dependent infection of cells and animals

Zhang, Lei; Zhang, Chenglin; Ojcius, David M.; Sun, Dexter; Zhao, Jun; Lin, Xiaojie; Li, Liwei; Li, Lanjuan; Yan, Jie

doi:10.1111/j.1365-2958.2012.07985.x

Cited by 86 publications

(95 citation statements)

References 73 publications

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“…The lack of involvement in disease pathogenesis by the majority of exoproteins is in agreement with the findings of previous studies on L. interrogans virulence genes which have demonstrated that the majority of genes are dispensable for virulence (27,68). Moreover, with the exception of a catalase gene (katE) (34) and a collagenase gene (24), the genes that have been demonstrated to be essential for virulence, such as HtpG (63), Loa22 (69), and those involved in motility (11,12), LPS biosynthesis (13), heme metabolism (70), and adhesion (71,72), have orthologues in the nonpathogenic species L. biflexa. In combination with the finding that the majority of L. interrogans exoproteins have orthologues in L. biflexa, this evidence further supports the theory that L. interrogans evolved from L. biflexa.…”

Section: Discussionmentioning

confidence: 69%

Pathogenic Leptospira interrogans Exoproteins Are Primarily Involved in Heterotrophic Processes

et al. 2015

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bLeptospirosis is a life-threatening and emerging zoonotic disease with a worldwide annual occurrence of more than 1 million cases. Leptospirosis is caused by spirochetes belonging to the genus Leptospira. The mechanisms of disease manifestation in the host remain elusive, and the roles of leptospiral exoproteins in these processes have yet to be determined. Our aim in this study was to assess the composition and quantity of exoproteins of pathogenic Leptospira interrogans and to construe how these proteins contribute to disease pathogenesis. Label-free quantitative mass spectrometry of proteins obtained from Leptospira spirochetes cultured in vitro under conditions mimicking infection identified 325 exoproteins. The majority of these proteins are conserved in the nonpathogenic species Leptospira biflexa, and proteins involved in metabolism and energy-generating functions were overrepresented and displayed the highest relative abundance in culture supernatants. Conversely, proteins of unknown function, which represent the majority of pathogen-specific proteins (presumably involved in virulence mechanisms), were underrepresented. Characterization of various L. interrogans exoprotein mutants in the animal infection model revealed host mortality rates similar to those of hosts infected with wild-type L. interrogans. Collectively, these results indicate that pathogenic Leptospira exoproteins primarily function in heterotrophic processes (the processes by which organisms utilize organic substances as nutrient sources) to maintain the saprophytic lifestyle rather than the virulence of the bacteria. The underrepresentation of proteins homologous to known virulence factors, such as toxins and effectors in the exoproteome, also suggests that disease manifesting from Leptospira infection is likely caused by a combination of the primary and potentially moonlight functioning of exoproteins.

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Section: Discussionmentioning

confidence: 69%

Pathogenic Leptospira interrogans Exoproteins Are Primarily Involved in Heterotrophic Processes

et al. 2015

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“…L. interrogans transposon mutants disrupted in katE were constructed to assess the viability of these mutants under conditions of oxidative stress and during in vivo infection. Complementation in L. interrogans is extremely difficult and has been documented only twice (49,67). We compensated for this lack of a genetic "knock-in" capability by constructing independent mutations in two different L. interrogans serovars (L. interrogans serovar Pomona mutant strain P3 and L. interrogans serovar Manilae mutant strain m69) and assessing if similar results were obtained with each of these mutants.…”

Section: Resultsmentioning

confidence: 99%

Leptospira interrogans Catalase Is Required for Resistance to H ₂ O ₂ and for Virulence

et al. 2012

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h Pathogenic Leptospira spp. are likely to encounter higher concentrations of reactive oxygen species induced by the host innate immune response. In this study, we characterized Leptospira interrogans catalase (KatE), the only annotated catalase found within pathogenic Leptospira species, by assessing its role in resistance to H 2 O 2 -induced oxidative stress and during infection in hamsters. Pathogenic L. interrogans bacteria had a 50-fold-higher survival rate under H 2 O 2 -induced oxidative stress than did saprophytic L. biflexa bacteria, and this was predominantly catalase dependent. We also characterized KatE, the only annotated catalase found within pathogenic Leptospira species. Catalase assays performed with recombinant KatE confirmed specific catalase activity, while protein fractionation experiments localized KatE to the bacterial periplasmic space. The insertional inactivation of katE in pathogenic Leptospira bacteria drastically diminished leptospiral viability in the presence of extracellular H 2 O 2 and reduced virulence in an acute-infection model. Combined, these results suggest that L. interrogans KatE confers in vivo resistance to reactive oxygen species induced by the host innate immune response.

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“…Mutagenesis and biochemical studies found that integrin receptors exhibited variable degrees of affinity to organisms with the analogs or mutants of the RGD motif, depending on the property of the integrin-binding protein (44). Individual residues within the RGD motif in surface proteins of many bacteria (such as Shigella, Leptospira, and Streptococcus species) played a dominant role in binding to integrin receptors (45)(46)(47). However, in the type IV secretion system (T4SS) protein CagL of Helicobacter pylori, all three residues in the RGD motif are important for integrin binding, as evidenced that the finding that replacement of each of these residues with alanine abolished the adhesion function (48).…”

Section: Discussionmentioning

confidence: 99%

Roles of the Putative Integrin-Binding Motif of the Human Metapneumovirus Fusion (F) Protein in Cell-Cell Fusion, Viral Infectivity, and Pathogenesis

Wei

Zhang

Cai

et al. 2014

J Virol

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Human metapneumovirus (hMPV) is a relatively recently identified paramyxovirus that causes acute upper and lower respiratory tract infection. Entry of hMPV is unusual among the paramyxoviruses, in that fusion is accomplished by the fusion (F) protein without the attachment glycoprotein (G protein). It has been suggested that hMPV F protein utilizes integrin ␣v␤1 as a cellular receptor. Consistent with this, the F proteins of all known hMPV strains possess an integrin-binding motif ( 329 RGD 331 ). The role of this motif in viral entry, infectivity, and pathogenesis is poorly understood. Here, we show that ␣5␤1 and ␣v integrins are essential for cell-cell fusion and hMPV infection. Mutational analysis found that residues R329 and G330 in the 329 RGD 331 motif are essential for cell-cell fusion, whereas mutations at D331 did not significantly impact fusion activity. Furthermore, fusion-defective RGD mutations were either lethal to the virus or resulted in recombinant hMPVs that had defects in viral replication in cell culture. In cotton rats, recombinant hMPV with the R329K mutation in the F protein (rhMPV-R329K) and rhMPV-D331A exhibited significant defects in viral replication in nasal turbinates and lungs. Importantly, inoculation of cotton rats with these mutants triggered a high level of neutralizing antibodies and protected against hMPV challenge. Taken together, our data indicate that (i) ␣5␤1 and ␣v integrins are essential for cell-cell fusion and viral replication, (ii) the first two residues in the RGD motif are essential for fusion activity, and (iii) inhibition of the interaction of the integrin-RGD motif may serve as a new target to rationally attenuate hMPV for the development of live attenuated vaccines. IMPORTANCEHuman metapneumovirus (hMPV) is one of the major causative agents of acute respiratory disease in humans. Currently, there is no vaccine or antiviral drug for hMPV. hMPV enters host cells via a unique mechanism, in that viral fusion (F) protein mediates both attachment and fusion activity. Recently, it was suggested that hMPV F protein utilizes integrins as receptors for entry via a poorly understood mechanism. Here, we show that ␣5␤1 and ␣v integrins are essential for hMPV infectivity and F proteinmediated cell-cell fusion and that the integrin-binding motif in the F protein plays a crucial role in these functions. Our results also identify the integrin-binding motif to be a new, attenuating target for the development of a live vaccine for hMPV. These findings not only will facilitate the development of antiviral drugs targeting viral entry steps but also will lead to the development new live attenuated vaccine candidates for hMPV.

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The mammalian cell entry (Mce) protein of pathogenic Leptospira species is responsible for RGD motif‐dependent infection of cells and animals

Cited by 86 publications

References 73 publications

Pathogenic Leptospira interrogans Exoproteins Are Primarily Involved in Heterotrophic Processes

Pathogenic Leptospira interrogans Exoproteins Are Primarily Involved in Heterotrophic Processes

Leptospira interrogans Catalase Is Required for Resistance to H ₂ O ₂ and for Virulence

Roles of the Putative Integrin-Binding Motif of the Human Metapneumovirus Fusion (F) Protein in Cell-Cell Fusion, Viral Infectivity, and Pathogenesis

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The mammalian cell entry (Mce) protein of pathogenic Leptospira species is responsible for RGD motif‐dependent infection of cells and animals

Cited by 86 publications

References 73 publications

Pathogenic Leptospira interrogans Exoproteins Are Primarily Involved in Heterotrophic Processes

Pathogenic Leptospira interrogans Exoproteins Are Primarily Involved in Heterotrophic Processes

Leptospira interrogans Catalase Is Required for Resistance to H 2 O 2 and for Virulence

Roles of the Putative Integrin-Binding Motif of the Human Metapneumovirus Fusion (F) Protein in Cell-Cell Fusion, Viral Infectivity, and Pathogenesis

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Leptospira interrogans Catalase Is Required for Resistance to H ₂ O ₂ and for Virulence