Unraveling Gardnerella vaginalis Surface Proteins Using Cell Shaving Proteomics

Abstract

Gardnerella vaginalis is one of the main etiologic agents of bacterial vaginosis (BV). This infection is responsible for a wide range of public health costs and is associated with several adverse outcomes during pregnancy. Improving our understanding of G. vaginalis protein cell surface will assist in BV diagnosis. This study represents the first proteomic approach that has analyzed the exposed proteins on G. vaginalis cell surface using a shaving approach. The 261 G. vaginalis proteins identified using this approach were analyzed with bioinformatic tools to detect characteristic motifs from surface-exposed proteins, such as signal peptides (36 proteins), lipobox domains (17 proteins), LPXTG motifs (5 proteins) and transmembrane alpha-helices (66 proteins). One third of the identified proteins were found to have at least one typical motif of surface-exposed proteins. Furthermore, the subcellular location was examined using two predictors (PSORT and Gpos-mPLoc). These bioinformatic tools classified 17% of the identified proteins as surface-associated proteins. Interestingly, we identified 13 members of the ATP-binding cassette (ABC) superfamily, which were mainly involved in the translocation of various substrates across membranes. To validate the location of the G. vaginalis surface-exposed proteins, an immunofluorescence assay with antibodies against Escherichia coli GroEL was performed to reveal the extracellular location of the moonlighting GroEL. In addition, monoclonal antibodies (mAb) against G. vaginalis Cna protein were produced and used to validate the location of Cna on the surface of the G. vaginalis. These high affinity anti-Cna mAb represent a useful tool for the study of this pathogenic microorganism and the BV.

Cholesterol-Dependent Cytolysins Produced by Vaginal Bacteria: Certainties and Controversies

“…may adopt the planktonic style of growth by modulating the gene expression profile (Swidsinski et al, 2014;Castro et al, 2019). Certain Gardnerella species or genomic subgroups may have a reduced capacity to adhere to epithelial cells and form a biofilm (Castro et al, 2015;Janulaitiene et al, 2018), probably due to differences in proteins that contribute to and participate in these activities (Harwich et al, 2010;Marín et al, 2018).…”

The genital tract and rectal microbiomes: their role in HIV susceptibility and prevention in women

“…Metaproteomics can provide important information on vaginal bacterial community structure, diversity and function and can further be applied to cultured isolates to better understand the protein repertoire expressed by individual vaginal bacteria. More recently, a “cell shaving proteomic” approach was used to identify 261 cell surface‐associated proteins of G. vaginalis in culture . This technology has several advantages as the metaproteome reflects the actual protein output, which may diverge from measures of bacterial community structure defined by amplicon sequencing, gene content (SMS) or metatranscriptomes .…”

Identification of surface proteins in a clinical Staphylococcus haemolyticus isolate by bacterial surface shaving

“…We selected one clinical strain with good adhesive and biofilm forming properties, and performed bacterial surface shaving. To date, most surface protein expression analyses are performed on bacteria incubated in bacterial growth medium [18][19][20][21][22]. As S. haemolyticus constitute a significant proportion of the skin microbiota of humans [1,48,49], we decided to choose a more biological relevant condition to study protein expression; incubation of S. haemolyticus with keratinocytes prior to bacterial surface shaving.…”

“…Several studies on surface proteins and their relevance in host-pathogen interactions and virulence have been performed after bacterial growth in standard laboratory medium [18][19][20][21][22]. In order to mimic a more biological relevant host-microbe interaction, we developed a novel method to investigate expressed surface proteins of a clinical S. haemolyticus isolate after colonization of human keratinocytes (HaCaT) before bacterial surface shaving was performed ( Fig.…”