title: UDP-N-Acetylglucosamine enolpyruvyl transferase (MurA) of Acinetobacter baumannii (AbMurA): Structural and functional properties.
abstract: Peptidoglycan (PG) is the key component of the bacterial cell wall. The enzyme UDP-N-Acetylglucosamine Enolpyruvyl Transferase (MurA) catalyzes the transfer of enolpyruvate from phosphoenolpyruvate (PEP) to uridinediphospho-N-acetylglucosamine (UNAG), which is the first committed step of PG biosynthesis. Here, we present the biochemical and structural features of the MurA enzyme of the opportunistic pathogen Acinetobacter baumannii (AbMurA). The recombinant AbMurA exists as a monomer in solution and shows optimal activity at pH 7.5 and 37°C. The Km for UDP-N-acetylglucosamine was 1.062±0.09mM and for PEP was 1.806±0.23mM. The relative enzymatic activity was inhibited ∼3 fold in the presence of 50mM fosfomycin (FFQ). Superimposition of the AbMurA model with E. coli demonstrated key structural similarity in the FFQ-binding site. AbMurA also has a surface loop that contains the active site Cys116 that interact with FFQ. Sequence analysis indicates the presence of the five conserved amino acids, i.e., K22, C116, D306, D370 and L371, required for the functional activity like other MurA enzymes from different bacteria. MurA enzymes are indispensable for cell integrity and their lack of counterparts in eukaryotes suggests them to be a promising drug target.
authors.affiliation: Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong 793022, India.
authors.forename: Amit
authors.initials: A
authors.lastname: Sonkar
authors.affiliation: Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong 793022, India.
authors.forename: Harish
authors.initials: H
authors.lastname: Shukla
authors.affiliation: Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong 793022, India.
authors.forename: Rohit
authors.initials: R
authors.lastname: Shukla
authors.affiliation: Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong 793022, India.
authors.forename: Jupitara
authors.initials: J
authors.lastname: Kalita
authors.affiliation: Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong 793022, India.
authors.forename: Tripti
authors.initials: T
authors.lastname: Pandey
authors.affiliation: Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong 793022, India. Electronic address: timir.tripathi@gmail.com.
authors.forename: Timir
authors.initials: T
authors.lastname: Tripathi
mesh_terms: D040981:Acinetobacter baumannii / Q000201:enzymology*; D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D020134:Catalytic Domain; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology; D005578:Fosfomycin / Q000378:metabolism / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D062105:Molecular Docking Simulation; D010802:Phylogeny; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013696:Temperature
chemical_list: D004791:Enzyme Inhibitors; D005578:Fosfomycin; D019883:Alkyl and Aryl Transferases; C022566:UDP-N-acetylglucosamine 1-carboxyvinyltransferase
keywords: Acinetobacter baumannii; Fosfomycin; Homology modeling; Molecular dynamic simulation; UDP-N-Acetylglucosamine enolpyruvyl transferase