title: Single-molecule dynamics of lysozyme processing distinguishes linear and cross-linked peptidoglycan substrates.
abstract: The dynamic processivity of individual T4 lysozyme molecules was monitored in the presence of either linear or cross-linked peptidoglycan substrates. Single-molecule monitoring was accomplished using a novel electronic technique in which lysozyme molecules were tethered to single-walled carbon nanotube field-effect transistors through pyrene linker molecules. The substrate-driven hinge-bending motions of lysozyme induced dynamic electronic signals in the underlying transistor, allowing long-term monitoring of the same molecule without the limitations of optical quenching or bleaching. For both substrates, lysozyme exhibited processive low turnover rates of 20-50 s(-1) and rapid (200-400 s(-1)) nonproductive motions. The latter nonproductive binding events occupied 43% of the enzyme's time in the presence of the cross-linked peptidoglycan but only 7% with the linear substrate. Furthermore, lysozyme catalyzed the hydrolysis of glycosidic bonds to the end of the linear substrate but appeared to sidestep the peptide cross-links to zigzag through the wild-type substrate.
authors.affiliation: Institute for Surface and Interface Science, University of California, Irvine, California 92697, USA.
authors.forename: Yongki
authors.initials: Y
authors.lastname: Choi
authors.forename: Issa S
authors.initials: IS
authors.lastname: Moody
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Sims
authors.forename: Steven R
authors.initials: SR
authors.lastname: Hunt
authors.forename: Brad L
authors.initials: BL
authors.lastname: Corso
authors.forename: David E
authors.initials: DE
authors.lastname: Seitz
authors.forename: Larry C
authors.initials: LC
authors.lastname: Blaszczak
authors.forename: Larry C
authors.initials: LC
authors.lastname: Blaszcazk
authors.forename: Philip G
authors.initials: PG
authors.lastname: Collins
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Weiss
mesh_terms: D017122:Bacteriophage T4 / Q000201:enzymology; D055162:Biocatalysis; D006868:Hydrolysis; D056004:Molecular Dynamics Simulation; D009113:Muramidase / Q000737:chemistry / Q000378:metabolism*; D037742:Nanotubes, Carbon / Q000737:chemistry; D010457:Peptidoglycan / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism
chemical_list: D037742:Nanotubes, Carbon; D010457:Peptidoglycan; D009113:Muramidase