TABLE 1.
Expression and relative quantification of putative plasminogen receptors in strains B31–A3, ospC-ko, and ospC-comp
Borrelia plasminogen-binding protein (BPBP), BbCRASP-1 (cspA), and members of the OspE- and OspF-related proteins, all of which have been proposed as potential plasminogen receptors, are expressed at similar levels in all experimental strains as determined by the precursor peak intensities of the identified peptides in mass spectrometry analyses. As expected, OspC was detected only in strains B31–A3 and ospC-comp. Thus, no hypothesized plasminogen receptor aside from OspC can account for observed differences in plasminogen binding among these strains. Protein description, accession numbers, peptide sequences, precursor ion m/z, and the charge states (z) are listed. ND means not detected.
| Protein peptidea | GenBankTM accession no. | Precursor m/z, z | Precursor peak intensitiesb |
||
|---|---|---|---|---|---|
| B31–A3 | ospC-ko | ospC-comp | |||
| Outer surface protein C (OspC) | NP_047005 | ||||
| GPNLTEISK | 480.2, 2 | 1.25 × 108 | ND | 1.40 × 108 | |
| EVEALLSSIDEIAAK | 794.8, 2 | 1.25 × 107 | ND | 1.79 × 107 | |
| ELTSPVVAESPK | 629.3, 2 | 8.44 × 107 | ND | 9.63 × 107 | |
| BPBP | NP_212462 | ||||
| NAQEYFDETVPESELGIK | 1035.5, 2 | 8.36 × 108 | 7.03 × 108 | 4.60 × 108 | |
| KLLAEAGYPDGK | 631.7, 2 | 1.23 × 107 | 5.36 × 107 | 8.88 × 107 | |
| IRDDYYSGLK | 410.9, 3 | 2.84 × 108 | 1.37 × 108 | 5.28 × 108 | |
| BbCRASP-1 (CspA) | NP_045741 | ||||
| TLYSSLDYK | 545.6, 2 | 7.52 × 107 | 6.05 × 107 | 8.31 × 107 | |
| DFDTLKPAFY | 609.2, 2 | 7.99 × 107 | 8.89 × 107 | 6.45 × 107 | |
| KITNPGENTQNFEDK | 579.5, 3 | 3.35 × 107 | 4.58 × 107 | 5.02 × 107 | |
| OspE group | |||||
| ErpA (BbCRASP-5) | NP_051199 | ||||
| IHTSYDEQSNGEVKVKK | 981.7, 2 | 4.68 × 107 | 4.79 × 107 | 2.59 × 107 | |
| ErpP (BbCRASP-3) | NP_051449 | ||||
| TAEYAIPLEVLKK | 737.1, 2 | 3.45 × 106 | 2.14 × 106 | 8.41 × 106 | |
| ErpC (BbCRASP-4) | AAC34910 | ||||
| KIEFSEFTVK | 614.9, 2 | 1.28 × 107 | 1.20 × 107 | 1.31 × 107 | |
| OspF group | |||||
| ErpG | NP_051244 | ||||
| QNVKEKVEGFLDK | 512.0, 3 | 5.94 × 107 | 4.32 × 107 | 9.46 × 107 | |
| EKEIQELK | 1016.8, 1 | 1.01 × 108 | 1.41 × 108 | 1.34 × 108 | |
| ErpL | NP_051372 | ||||
| NSEQNLESSEQNVK | 803.2, 2 | 1.14 × 108 | 1.44 × 108 | 8.95 × 107 | |
| NSEQNLESSEQNVKK | 867.3, 2 | 1.40 × 108 | 1.54 × 108 | 2.98 × 108 | |
| Elp | |||||
| ErpX | NP_051509 | ||||
| LNKDNK | 732.5, 1 | 2.52 × 107 | 1.54 × 107 | 3.40 × 107 | |
| ENVDVSEIKEDLEK | 549.5, 3 | 1.13 × 108 | 6.37 × 107 | 5.39 × 107 | |
a The peptides listed from each protein were detected with high confidence by mass spectrometry (ΔCn >0.1 and the cross-correlation score (Xcorr) is greater than 1.5, 2.0, or 2.5 for peptides with charges (z) of +1, +2, or +3, respectively) and checked visually to confirm correct peptide identification.
b Precursor peak intensities of each peptide are listed for wild-type (B31–A3), OspC knockout (ospC-ko), and complement (ospC-comp) strains. Assays of 0.50 pm/μl bovine cytochrome c digest (Dionex) under similar conditions yielded peak intensities of (5–10) × 108 for major peptides.