, 2002). Although the cell wall binding domain might be essential for the enzyme’s lytic activity, some endolysins were reported to exhibit higher antibacterial activity after removal of their C-terminal domains (Borysowski Selleckchem PI3K Inhibitor Library et al., 2006). The mechanism of cell wall substrate recognition and the specificity and binding ability of the endolysins have been studied. Significant progress has been made using endolysins linked with green fluorescent protein (GFP). The specific

binding of endolysins to the cell wall substrate has been visualized by fluorescence microscopy (Loessner et al., 2002; Low et al., 2005; Korndoerfer et al., 2006; Briers et al., 2007). Corynephage BFK20, a lytic phage of the industrial producer

Brevibacterium flavum CCM 251, is the first corynephage whose genome was completely sequenced and analyzed (EMBL accession no. AJ278322) (Bukovska et al., 2006). Using a bioinformatics approach, three potential lytic genes in one cluster were identified on the BFK20 genome. In this study, we characterized BFK20 endolysin (gp24′) in detail. We have confirmed the two-domain structure PLX3397 cell line of this endolysin. The catalytic and cell wall binding domains were separately cloned, isolated and characterized. The biological activities of BFK20 endolysin and its catalytic domain were demonstrated. The C-terminal cell wall binding domain appears to be unrelated to any of the previously known cell wall binding domains. Amino acid sequences of endolysins were searched using blastp (Altschul et al., 1997) on the nonredundant database using the sequence of gp24′ as the query. We selected those sequences with E-values over 9e−07 and one sequence from Corynebacterium diphtheriae NCTC 13129 with an E-value 3e−04. These sequences were aligned using clustalw2 (Thompson et al., 1994) and manually adjusted. A domain search was performed against the Pfam databases (Bateman et al., 2004). The bacterial strains used in this study were B. flavum CCM 251 (an l-lysine production strain), B. flavum strains ATCC

21127, 21128, 21129 and 21474, Brevibacterium Orotic acid lactofermentum BLOB (a mutant derived from B. lactofermentum ATCC 21798) (Santamaria et al., 1984), Corynebacterium glutamicum RM3 (Schäfer et al., 1990) and Bacillus subtilis wt PY79 (Youngman et al., 1984). Escherichia coli XL1 Blue (Stratagene) was used for cloning experiments and E. coli BL21(DE3) (Novagen) was used as a host for the expression of recombinant proteins. Escherichia coli strains were grown at 37 °C, and corynebacteria and bacilli were grown at 30 °C in Luria–Bertani medium (Sambrook & Russel, 2001). Corynephage BFK20 was propagated on B. flavum CCM 251 according to Bukovska et al. (2006). BFK20 phage particle isolation and phage DNA purification were performed according to Sambrook & Russell (2001).