title: Biochemical and Structural Analysis of a Novel Esterase from Caulobacter crescentus related to Penicillin-Binding Protein (PBP).
abstract: Considering that the prevalence of antibiotic-resistant pathogenic bacteria is largely increasing, a thorough understanding of penicillin-binding proteins (PBPs) is of great importance and crucial significance because this enzyme family is a main target of β-lactam-based antibiotics. In this work, combining biochemical and structural analysis, we present new findings that provide novel insights into PBPs. Here, a novel PBP homologue (CcEstA) from Caulobacter crescentus CB15 was characterized using native-PAGE, mass spectrometry, gel filtration, CD spectroscopy, fluorescence, reaction kinetics, and enzyme assays toward various substrates including nitrocefin. Furthermore, the crystal structure of CcEstA was determined at a 1.9 Å resolution. Structural analyses showed that CcEstA has two domains: a large α/β domain and a small α-helix domain. A nucleophilic serine (Ser68) residue is located in a hydrophobic groove between the two domains along with other catalytic residues (Lys71and Try157). Two large flexible loops (UL and LL) of CcEstA are proposed to be involved in the binding of incoming substrates. In conclusion, CcEstA could be described as a paralog of the group that contains PBPs and β-lactamases. Therefore, this study could provide new structural and functional insights into the understanding this protein family.
authors.affiliation: Department of Chemistry, College of Natural Science, Sookmyung Women's University, Seoul 140-742, Korea.|Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, 440-746, Korea.
authors.forename: Bum Han
authors.initials: BH
authors.lastname: Ryu
authors.affiliation: Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, 440-746, Korea.
authors.forename: Tri Duc
authors.initials: TD
authors.lastname: Ngo
authors.affiliation: Department of Chemistry, College of Natural Science, Sookmyung Women's University, Seoul 140-742, Korea.|Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, 440-746, Korea.
authors.forename: Wanki
authors.initials: W
authors.lastname: Yoo
authors.affiliation: Department of Chemistry, College of Natural Science, Sookmyung Women's University, Seoul 140-742, Korea.
authors.forename: Sojeong
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Chemistry, College of Natural Science, Sookmyung Women's University, Seoul 140-742, Korea.
authors.forename: Boo-Young
authors.initials: BY
authors.lastname: Kim
authors.affiliation: Department of Chemistry, College of Natural Science, Sookmyung Women's University, Seoul 140-742, Korea.
authors.forename: Euijoo
authors.initials: E
authors.lastname: Lee
authors.affiliation: Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, 440-746, Korea.
authors.forename: Kyeong Kyu
authors.initials: KK
authors.lastname: Kim
authors.affiliation: Department of Chemistry, College of Natural Science, Sookmyung Women's University, Seoul 140-742, Korea.
authors.forename: T Doohun
authors.initials: TD
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020134:Catalytic Domain; D016935:Caulobacter crescentus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D002942:Circular Dichroism; D003001:Cloning, Molecular / Q000379:methods*; D018360:Crystallography, X-Ray; D007700:Kinetics; D008958:Models, Molecular; D046915:Penicillin-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017433:Protein Structure, Secondary; D012694:Serine / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D046915:Penicillin-Binding Proteins; D012694:Serine; D002265:Carboxylic Ester Hydrolases; C098953:EstA protein, bacteria