Other Cbps present additional domains with identified enzymatic functions (CbpG, CbpE, Lyt proteins). Finally some Cbps exhibit additional predicted domains of unknown functions (CbpL, CbpA, CbpD). All the genes encoding the Cbps were cloned, excluding genes coding for the Lyt see more proteins as their roles are well documented. CbpE was already cloned in the laboratory . PspA, CbpN and CbpD were not expressed. CbpG and CbpK were expressed as an insoluble form: these proteins were not studied further. CbpA, CbpE, CbpF, CbpI, CbpJ, CbpL and CbpM were successfully purified. Expression and purification Epacadostat concentration of
LPXTG proteins A comparable analysis has been conducted with the LPXTG proteins (Fig 3). There are genes for 19 and 13 LPXTG family members identified in the TIGR4 and R6 genomes, respectively check details [28, 29]. Ten LPXTG proteins are common to the R6 and TIGR4 genomes meaning that some of these surface-exposed proteins are specific to either R6 or TIGR4 strains. Five LPXTG proteins are specific of TIGR4, among which the pilin proteins encoded at loci SP0462, SP0463 and SP0464 and thought to be covalently associated
to each other via their LPXTG-like motif by specific pilus-sortase enzymes . Because these particular LPXTG proteins are not linked to the peptidoglycan by the housekeeping sortase A, they have not been included in this study. Two other LPXTG proteins are present in the TIGR4 strain and absent from the R6 strain: the metalloprotease ZmpC and PsrP, a very large protein (4776 aa) essentially
composed of a serine rich region . Three new R6 orthologs were identified: proteins EndoD (SP0498 = spr0440), ZmpB (SP0664 = spr0581) and ZmpA (SP1154 = spr1042) (Fig 3). NanA (spr1536) and PclA (= spr1403) are present in the R6 strain but not in TIGR4. Among the LPXTG proteins, spr0400 does not have a LPXTG motif, as was initially reported  nor a Gram-positive anchor, was thus excluded from our study. CbpA (SP2190) is identified MycoClean Mycoplasma Removal Kit both as Cbp and LPXTG protein in the TIGR4 annotations. As we did not find a LPXTG motif in SP2190, it was excluded from the LPXTG proteins list and kept with the Cbps (Fig 2 &3). The initial inaccurate annotation as an LPXTG protein likely originates from the presence of an allelic variant of CbpA harboring an LPXTG motif in some pneumococcal strains [15, 39]. Finally, the R6 strain has 15 genes encoding for LPXTG proteins compared to 18 for the TIGR4 strain. Protein sizes range from 202 aa (MucB) to 4776 aa (PsrP). Some of them are enzymes (Fig 3) while others may be involved in molecular recognition (SpuA and SpnHL harbor carbohydrate binding modules…). The sequence identity between LPXTG orthologs found in R6 and TIGR4 strains ranged between 89% and 100%, except for the ZmpB protein which sequence identity is 52%.