Localisation of outer membrane proteins in Treponema denticola by quantitative proteome analyses of outer membrane vesicles and cellular fractions

ABSTRACT: The identification and localisation of outer membrane proteins (Omps) and lipoproteins in pathogenic treponemes such as T. denticola (periodontitis) and T. pallidum (syphilis) has been challenging largely due to the structural uniqueness of their outer membranes (OM), the high abundance of inner membrane (IM) lipoproteins and the low abundance of Omps. In this study, label-free quantitative proteomics using MaxQuant was applied to naturally produced outer membrane vesicles (OMVs) and cellular fractions to identify 1448 T. denticola proteins. Of these, 90 proteins were localised to the OM comprising 59 lipoproteins, 25 β-barrel proteins and six other putative OM-associated proteins. 28 lipoproteins were localised to the IM and 43 proteins were assigned to the periplasm. The signal cleavage regions of the OM and IM lipoprotein sequences were different and may reveal the signal for their differential localisation to the OM and IM. Proteins significantly enriched in OMVs included dentilisin, proteins containing leucine-rich repeats and several lipoproteins containing FGE-sulfatase domains. Blue native PAGE analysis enabled the native size of the dentilisin complex and Msp to be determined and revealed that the abundant β-barrel Omps TDE2508 and TDE1717 formed large complexes. Several Omps were identified to have homologs in T. pallidum that have not yet been identified.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Treponema Denticola Atcc 35405

SUBMITTER: Paul Veith  

LAB HEAD: Eric C Reynolds

PROVIDER: PXD011495 | Pride | 2019-02-20

REPOSITORIES: Pride