title: The secondary cell wall polysaccharide of Bacillus anthracis provides the specific binding ligand for the C-terminal cell wall-binding domain of two phage endolysins, PlyL and PlyG.
abstract: Endolysins are bacteriophage enzymes that lyse their bacterial host for phage progeny release. They commonly contain an N-terminal catalytic domain that hydrolyzes bacterial peptidoglycan (PG) and a C-terminal cell wall-binding domain (CBD) that confers enzyme localization to the PG substrate. Two endolysins, phage lysin L (PlyL) and phage lysin G (PlyG), are specific for Bacillus anthracis. To date, the cell wall ligands for their C-terminal CBD have not been identified. We recently described structures for a number of secondary cell wall polysaccharides (SCWPs) from B. anthracis and B. cereus strains. They are covalently bound to the PG and are comprised of a -ManNAc-GlcNAc-HexNAc- backbone with various galactosyl or glucosyl substitutions. Surface plasmon resonance (SPR) showed that the endolysins PlyL and PlyG bind to the SCWP from B. anthracis (SCWPBa) with high affinity (i.e. in the μM range with dissociation constants ranging from 0.81 × 10(-6) to 7.51 × 10(-6) M). In addition, the PlyL and PlyG SCWPBa binding sites reside with their C-terminal domains. The dissociation constants for the interactions of these endolysins and their derived C-terminal domains with the SCWPBa were in the range reported for other protein-carbohydrate interactions. Our findings show that the SCWPBa is the ligand that confers PlyL and PlyG lysin binding and localization to the PG. PlyL and PlyG also bound the SCWP from B. cereus G9241 with comparable affinities to SCWPBa. No detectable binding was found to the SCWPs from B. cereus ATCC (American Type Culture Collection) 10987 and ATCC 14579, thus demonstrating specificity of lysin binding to SCWPs.
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA.
authors.forename: Jhuma
authors.initials: J
authors.lastname: Ganguly
authors.forename: Lieh Y
authors.initials: LY
authors.lastname: Low
authors.forename: Nazia
authors.initials: N
authors.lastname: Kamal
authors.forename: Elke
authors.initials: E
authors.lastname: Saile
authors.forename: L Scott
authors.initials: LS
authors.lastname: Forsberg
authors.forename: Gerardo
authors.initials: G
authors.lastname: Gutierrez-Sanchez
authors.forename: Alex R
authors.initials: AR
authors.lastname: Hoffmaster
authors.forename: Robert
authors.initials: R
authors.lastname: Liddington
authors.forename: Conrad P
authors.initials: CP
authors.lastname: Quinn
authors.forename: Russell W
authors.initials: RW
authors.lastname: Carlson
authors.forename: Elmar L
authors.initials: EL
authors.lastname: Kannenberg
mesh_terms: D000581:Amidohydrolases / Q000737:chemistry / Q000378:metabolism*; D000606:Amino Sugars / Q000737:chemistry; D001408:Bacillus anthracis / Q000737:chemistry / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D002473:Cell Wall / Q000737:chemistry* / Q000378:metabolism; D006601:Hexoses / Q000737:chemistry; D008024:Ligands; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000737:chemistry / Q000378:metabolism*; D011135:Polysaccharides, Bacterial / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000606:Amino Sugars; D001426:Bacterial Proteins; D006601:Hexoses; D008024:Ligands; D011135:Polysaccharides, Bacterial; D014764:Viral Proteins; C465450:PlyG lysin, gamma phage; D000581:Amidohydrolases; C506058:PlyL protein, Bacillus anthracis; D009238:N-Acetylmuramoyl-L-alanine Amidase
keywords: Bacillus anthracis; bacteriophage; endolysin; polysaccharide; secondary cell wall polymer