The human cervical-vaginal area contains proteins derived from microorganisms that may prevent or predispose women to gynecological conditions. The liquid Pap test fixative is an unexplored resource for analysis of microbial communities and the microbe-host interaction. Previously, we showed that the residual cell-free fixative from discarded Pap tests of healthy women could be used for mass spectrometry (MS) based proteomic identification of cervical-vaginal proteins. In this study, we reprocessed these MS raw data files for metaproteomic analysis to characterize the microbial community composition and function of microbial proteins in the cervical-vaginal region. This was accomplished by developing a customized protein sequence database encompassing microbes likely present in the vagina. High-mass accuracy data were searched against the protein FASTA database using a two-step search method within the Galaxy for proteomics platform. Data was analyzed by MEGAN6 (MetaGenomeAnalyzer) for phylogenetic and functional characterization. We identified over 300 unique peptides from a variety of bacterial phyla and Candida. Peptides corresponding to proteins involved in carbohydrate metabolism, oxidation-reduction, and transport were identified. By identifying microbial peptides in Pap test supernatants it may be possible to acquire a functional signature of these microbes, as well as detect specific proteins associated with cervical health and disease.
Bibliographical noteFunding Information:
We acknowledge the contributions of members of the University of Minnesota Core facilities to this project: James E. Johnson and Thomas McGowan at the University of Minnesota Supercomputing Institute for maintaining Galaxy-P; and staff at the University of Minnesota Center for Mass Spectrometry and Proteomics and the BioNet Tissue Procurement Facility for assistance with sample collection. We acknowledge the funding support of the Minnesota Ovarian Cancer Alliance and the Department of Defense Ovarian Cancer Research Program Pilot Award #W81XWH-16-1-0070 to A.P.N.S., and NSF grant 1458524 and NIH grant 1U24CA199347 for support to P.D.J. and T.J.G. from the Galaxy-P team at the University of Minnesota.
© 2018 The Author(s).