TABLE 2.
Homologs of polypeptides isolated as active ΔSPNuc fusions in L. lactis
| ΔSPNuc fusion | Protein homolog(s)a | Identity (%) | Aligned segmentb |
|---|---|---|---|
| Exp1 | Unidentified secreted protein Usp45 (L. lactis) | 29.7 | |
| P54 protein (Enterococcus faecium) | 24.8 | ||
| Exp2 | d,d-Carboxypeptidase DacA (S. pneumoniae) | 51.7 | |
| DacA (B. subtilis) | 42.0 | ||
| Exp3 | ORF258 (L. lactis phage BK5T) | 51.1 | |
| Exp5c | PBP1A (S. pneumoniae) | 53.5 | 175 (N-ter) |
| PBP1A (B. subtilis) | 36.8 | 175 (N-ter) | |
| Uvr402 (S. pneumoniae) | 88.1 | 280 (C-ter) | |
| UvrB, B subunit of exonuclease ABC (E. coli) | 66.7 | 280 (C-ter) | |
| Nlp1 | ss80 signal peptide (L. lactis; 30 aa identified) | 100.0 | 30 (N-ter) |
| ORF108, probable ABC transporter binding protein (B. subtilis) | 49.3 | ||
| Phosphate binding protein PstS (Mycobacterium intracellulare) | 28.9 | ||
| Nlp3 | Adhesin PsaA (S. pneumoniae) | 41.1 | |
| Manganese binding protein MntC (Synechocystis sp.) | 27.8 | ||
| Nlp4 | Protease maturation protein PrtM (Lactobacillus paracasei) | 36.4 | |
| PrtM (L. lactis) | 36.4 | ||
| Tmp2d | FtsL (S. pneumoniae; 76 aa) | 26.3 | 76 (C-ter) |
| Tmp3 | PBP1A (E. coli) | 27.8 | 156 (C-ter) |
| Tmp7 | PIP (L. lactis) | 25.2 |
The protein homologs presented have the highest identity scores and/or are characterized. Polypeptide lengths are given for those homologs for which only partial sequences are available. aa, amino acids.
Number of amino acids aligned to a database polypeptide. The lack of a number indicates that alignment was performed on the majority of the polypeptide. N-ter and C-ter indicate that homology is found at the N or C terminus, respectively, of the polypeptide fused to ΔSPNuc. With the exception of Tmp2 and Exp5, homologies correspond to the full length of polypeptides fused to ΔSPNuc.
Exp5 is a complex fusion, apparently obtained by cocloning and joining in frame a PBP1A homolog to a UvrB homolog. The significance of the homology between the Exp5 N terminus and PBP1A is reinforced by the homology between the ORFs upstream of exp5-Δnuc and pbp1A (S. pneumoniae). Note that Tmp3 and Exp5 N termini are both PBP1A homologs but differ from one another (only 25% identity).
Tmp2 appears to be a true FtsL homolog, as suggested by homology of the ORF found upstream of tmp2-Δnuc to S. pneumoniae ORFD and to B. subtilis ORFB, which are present upstream of ftsL in the pbpX and pbpB regions, respectively.