Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 10, 2008
Publication Date: N/A
Technical Abstract: Bacteriophage endolysins are peptidoglycan hydrolases and a potential new source of antimicrobials. A large subset of these proteins contain a C-terminal SH3b_5 cell wall binding domain that has been shown [for some] to be essential for accurate cell wall recognition and subsequent staphylolytic activity. We predict that these domains can be exploited for developing cell-type specific enzyme antimicrobials. To identify the conserved features of the staphylococcal SH3b domain, fifty-five proteins of staphylococcal (or phage) origin, harboring these C-terminal sequences have been aligned via Clustal, yielding five highly repetitive groups with >90% within group identity and <50% identity between groups. Four additional proteins were also identified that have <50% identity to the other 51. These five groups and four stand alone proteins comprise 9 unique SH3b domain containing staphylococcal peptidoglycan hydrolases. Representative proteins for each of the five groups, as well as the 4 independent SH3b_5 containing proteins have been isolated and tested for relative staphylolytic activity. Comparison of the nine unique Sh3b_5 domain sequences, reveals two distinct sub-groups with over-lapping but differentially conserved residues. To test the hypothesis that these domains could be useful in the construction of high activity, specie-specific enzyme antimicrobials, we have created two heterologous peptidoglycan hydrolase fusion enzymes. Each harbors either the SH3b domain from lysostaphin (a staphylococcal bacteriocin) or LysK (a staphylococcal phage endolysin) fused to a peptidoglycan hydrolase endopeptidase domain from the streptococcal 'Sa2 phage endolysin. These chimeric fusions confirm that this fusion protein strategy can be used to optimize and construct antimicrobials with enhanced anti-staphylococcal activity.