S-Space College of Agriculture and Life Sciences (농업생명과학대학) Dept. of Agricultural Biotechnology (농생명공학부) Theses (Ph.D. / Sc.D._농생명공학부)
Structural and functional studies of bacteriophage SPN1S endolysin
박테리오파지 SPN1S에서 유래한 endolysin의 구조와 기능에 대한 연구
- 농업생명과학대학 농생명공학부
- Issue Date
- 서울대학교 대학원
- Bacteriophage SPN1S; Endolysin; Salmonella typhimurium; Peptidoglycan-binding activity; Glycoside hydrolase
- 학위논문 (박사)-- 서울대학교 대학원 : 농생명공학부, 2015. 2. 이상기.
- Bacteriophage-originated endolysins have attracted great attentions as alternative antibiotic agents against antibiotic-resistant bacteria. Bacteriophage SPN1S infects the pathogenic Gram-negative bacterium Salmonella typhimurium and expresses endolysin for the release of phage progeny by degrading peptidoglycan of the host cell walls. Bacteriophage SPN1S endolysin exhibits high glycosidase activity against peptidoglycans, resulting in antimicrobial activity against a broad range of outer membrane-permeabilized Gram-negative bacteria. Here, the crystal structure of SPN1S endolysin is reported. The results clearly indicate that unlike most endolysins from Gram-negative bacteria background, the α-helical protein consists of two modular domains, a large and a small domain, with a concave groove between them. Comparison with other structurally homologous glycoside hydrolases indicated a possible peptidoglycan-binding site in the groove, and the presence of a catalytic dyad in the vicinity of the groove, one residue in a large domain and the other in a junction between the two domains. The catalytic dyad was further validated by antimicrobial activity assay against outer membrane-permeabilized Escherichia coli. The three-helix bundle in the small domain containing a novel class of sequence motif exhibited binding affinity against outer membrane-permeabilized E. coli and was therefore proposed as the peptidoglycan-binding domain. These structural and functional features suggest that endolysin from a Gram-negative bacterial background has peptidoglycan-binding activity and performs glycoside hydrolase activity through the catalytic dyad.