TABLE 2

Roles of the genes of the core SigX regulon in transformation

Function and locus tagaGeneRole or activity (reference[s])Transformation of mutants (reference[s])b
SMU no.SP no.SSA no.SMUSPSSA (45)
Recombination
    32700232157 radA DNA repair protein RadA (71)↓ (71)
    64409780749 coiA Recombination↓ (72)
    10011266 1185 dprA DNA-processing protein, mediates RecA (72, 73) loading onto internalized single-stranded DNA, competence shutoff (74–76)↓ (77)↓ (13, 74)
    196719080214 ssbB Single-stranded DNA binding, DNA protection (78)↓ (77)↓ (79–81)
    208519402245 recA Recombinase A, strand exchange (74, 82)↓ (77, 83)↓ (84)↓ (85)
Recombination (core in DpnII group)
    505 1734 1717 dpnA Single-strand methylase (56) ↓ (56)g
    506 1733 1716 dpnB DpnII restrictase targeting unmethylated double-stranded DNA (56)Yes (77)
    Uptake
    49822081836 coMFA ATP-dependent DNA/RNA helicase, translocase involved in single-stranded DNA uptake (86)↓ (87)
    49922071835 comFC Late competence protein (59)↓ (59, 87)
    53918080642 cilC, pilDSignal peptidase type IV, pilin cleavage (13, 88)↓ (39)↓ (13)
    62509540715 comEA Membrane protein with DNA-binding motif (double-stranded DNA receptor) (89)↓ (90)
    62609550716 comEC Membrane channel (59, 91)c↓ (90)
    197920450191Adenine-specific DNA methylase (13)↓ (50)Yesd (13)
    198020470190 comGG Minor pilin (92–94)↓ (50)↓ (13, 93)
    198120480189 comGF Minor pilin (92–94)↓ (50)↓ (93)
    198220490188 comGE Minor pilin (92–94)↓ (50)↓ (93)
    198320500187 comGD Minor pilin (92–94)↓ (50)↓ (93)
    198420510186 comGC Major pilin (92, 94)↓ (50)↓ (59, 92, 93)
    198520520185 comGB Competence protein, ABC transporter subunit (94)↓ (50)↓ (59, 93)
    198720530184 comGA Pilus assembly ATPase (94)↓ (50)↓ (59, 92, 93)
Lysis (CHAP domain conserved)
    8360036 lytF Murein hydrolase (39, 61, 77, 95)↓ (39, 77)
2201 cbpD Murein hydrolase (96)Yes (96)
Unknown functions in competenceh
    3250021 2160 dut Deoxyuridine 5′-triphosphate nucleotidohydrolaseYes (13)
    35419812117 rmuC, ccs50DNA recombination protein RmuCYes (13)
    35519802116 yhaM, cbf1CMP-binding factor 1, 23S RNA maturationYes (13)
    50022061834 yfiA Ribosome hibernation-promoting factor (Hpf), sigma factor (σ54) modulationYes (13)
    64509790751 pepB OligopeptidaseYes (13)
    76907821537 pilC Membrane protein of pilus assemblyYese (32, 39, 77)Yes (13)
    105510881218 radC DNA repair protein RadC↓ (39)Yes (45)
    197820440192 ackA Bifunctional acetaldehyde-coenzyme A/alcohol dehydrogenase (13, 97)Yes (97)Yes (93)
    208619412246 cinA Competence damage-inducible protein A (98)f (98)Yes (85)
  • a Gene locus tag as in GenBank (SMU, S. mutans UA159, accession no. AE014133 ; SP, S. pneumoniae, TIGR4 accession no. AE005672 ; in bold, S. pneumoniae G54, accession no. CP001015 ; SSA, S. sanguinis SK36, accession no. CP000387.1 ).

  • b Yes, deletion mutants not affected in transformation; ↓, >2-fold reduction.

  • c Unpublished data.

  • d 70% of WT.

  • e Results with CSP showed a <2-fold reduction, but in one of the studies without CSP, there were no transformants (32).

  • f Deletion of cinA affected the expression of the downstream gene recA, which was not fully restored by cinA complementation from a plasmid.

  • g Transformation with unmethylated DNA was reduced in the deletion mutant.

  • h Annotation at KEGG (99).