Fig 1.

Schematic representation of the C. acetobutylicum agrBDCA cluster (A) and alignment of confirmed and putative AgrD sequences (B). (A) The C. acetobutylicum agrBDCA cluster is predicted to comprise two independent transcriptional units (indicated by the dashed arrows), agrBD and agrCA. (B) The alignment shows the experimentally confirmed AgrD proteins from S. aureus (AgrD group I to IV), E. faecalis (LsrD), and L. plantarum (LamD), as well as selected putative AgrD sequences from other species. The latter included the following (locus tags are given in parentheses, if available, and identify the respective sequence in the alignment): C. acetobutylicum (CAC0079), Clostridium cellulovorans 743B (Clocel_1234, Clocel_1319, and Clocel_4254), Bacillus cereus G9241 (BCE_G9241_0529), Listeria innocua Clip11262 (Lin0042), Listeria monocytogenes EGD-e (Lmo0049), Clostridium butyricum 5521 (CBY_1631), Lactobacillus sakei subsp. sakei 23K (LSA1504), Clostridium difficile QCD-23m63 (CdifQCD-2_01797), Clostridium papyrosolvens DSM 2782 (Cpap_1451 and Cpap 2, the latter not annotated), Clostridium cellulolyticum H10 (Ccel_2126), Clostridium carboxidivorans P7 (CLCAR_0954), Clostridium botulinum ATCC 3502 (CBO0332A and CBO0339), Clostridium kluyveri (Ckluyveri; not annotated), C. beijerninckii NCIMB 8052 (Cbeij 1; not annotated), Clostridium perfringens SM101 (CPR_1531), C. difficile QCD-66c26 (CdifQC_16513), C. difficile 630 (CD2749A), Clostridium saccharolyticum WM1 (Closa_2479). The black triangle indicates confirmed and proposed processing sites downstream of the ring-encoding part of AgrD. A highly conserved proline, present in all sequences, is shaded gray. Note the sequence conservation immediately downstream of the proposed cleavage site and upstream of the conserved proline. For each AIP group, identities (*), conserved (:), and semiconserved substitutions (.) are displayed. Amino acids constituting the N-terminal tail of confirmed AIPs are underlined. Numbers indicate the total length of the AgrD sequence.